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Bubun N, Anetul E, Koinari M, Johnson PH, Makita LS, Freeman TW, Robinson LJ, Laman M, Karl S. Insufficient duration of insecticidal efficacy of Yahe ® insecticide-treated nets in Papua New Guinea. Malar J 2024; 23:175. [PMID: 38840196 PMCID: PMC11151609 DOI: 10.1186/s12936-024-05005-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 05/28/2024] [Indexed: 06/07/2024] Open
Abstract
BACKGROUND Insecticide-treated nets (ITNs) are the backbone of anti-malarial vector control in Papua New Guinea (PNG). Over recent years the quality and performance of ITNs delivered to PNG decreased, which has likely contributed to the stagnation in the malaria control effort in the country. The present study reports results from the first 24 months of a durability study with the ITN product Yahe LN® in PNG. METHODS The durability study was conducted in four villages on the northern coast of PNG, in an area with high malaria parasite transmission, following WHO-recommended methodology adapted to the local scenario. A cohort of n = 500 individually identifiable Yahe® ITNs was distributed by the PNG National Malaria Control Programme from October to December 2021. Insecticidal efficacy of the ITNs was tested using cone bioassays with fully pyrethroid susceptible Anopheles farauti colony mosquitoes at baseline and at 6 months intervals, alongside evaluation of physical integrity and the proportion of ITNs lost to follow-up. A questionnaire was used to collect information on ITN end user behaviour, such as the frequency of use and washing. The observations from the durability study were augmented with simulated laboratory wash assays. RESULTS Gradual uptake and replacement of previous campaign nets by the communities was observed, such that at 6 months 45% of all newly distributed nets were in use in their designated households. Insecticidal efficacy of the Yahe® nets, expressed as the percent 24 h mortality in cone bioassays decreased from 91 to 45% within the first 6 months of distribution, even though > 90% of study nets had never been washed. Insecticidal efficacy decreased further to < 20% after 24 months. ITNs accumulated physical damage (holes) at a rate similar to previous studies, and 35% were classified as 'too torn' by proportional hole index after 24 months. ITNs were lost to follow-up such that 61% of cohort nets were still present after 24 months. Laboratory wash assays indicated a rapid reduction in insecticidal performance with each consecutive wash such that average 24 h mortality was below 20% after 10 washes. CONCLUSION Yahe® ITNs are not performing as per label claim in an area with fully pyrethroid susceptible vectors, and should be investigated more comprehensively and in other settings for compliance with currently recommended durability and efficacy thresholds. The mass distribution of low quality ITN products with variable performance is one of the major ongoing challenges for global malaria control in the last decade.
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Affiliation(s)
- Nakei Bubun
- Papua New Guinea Institute of Medical Research, Madang, Madang, Papua New Guinea
| | - Evodia Anetul
- Papua New Guinea Institute of Medical Research, Madang, Madang, Papua New Guinea
| | - Melanie Koinari
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD, Australia
| | - Petrina H Johnson
- Papua New Guinea Institute of Medical Research, Madang, Madang, Papua New Guinea
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD, Australia
| | - Leo S Makita
- Papua New Guinea National Department of Health, National Capital District, Port Moresby, Papua New Guinea
| | - Timothy W Freeman
- Rotarians Against Malaria Papua New Guinea, National Capital District, Port Moresby, Papua New Guinea
| | - Leanne J Robinson
- Papua New Guinea Institute of Medical Research, Madang, Madang, Papua New Guinea
- Burnet Institute of Medical Research, Melbourne, VIC, Australia
| | - Moses Laman
- Papua New Guinea Institute of Medical Research, Madang, Madang, Papua New Guinea
| | - Stephan Karl
- Papua New Guinea Institute of Medical Research, Madang, Madang, Papua New Guinea.
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD, Australia.
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Lugenge AG, Odufuwa OG, Mseti JJ, Swai JK, Skovmand O, Moore SJ. Complete series method (CSM): a convenient method to reduce daily heterogeneity when evaluating the regeneration time (RT) of insecticide-treated nets (ITNs). Parasit Vectors 2024; 17:235. [PMID: 38778423 PMCID: PMC11110420 DOI: 10.1186/s13071-024-06323-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND "Regeneration time" (RT) denotes the time required to obtain a stable mortality rate for mosquitoes exposed to insecticide-treated nets (ITNs) after three consecutive washes of a net in a day. The RT informs the wash interval used to artificially age ITNs to simulate their lifetime performance under user conditions (20 washes). RT was estimated following World Health Organization (WHO) longitudinal method (LM) procedures. Longitudinal evaluation may introduce heterogeneity due to mosquito batch variability, complicating RT determination. To overcome this, nets at each stage of regeneration (i.e., 1, 2, 3, 5 and 7 days post wash) were prepared in advance and refrigerated; then, a complete regeneration series was tested with a single mosquito batch on 1 testing day, completing four series over 4 days. This study compared the complete series method (CSM) against the LM. METHODS The overall heterogeneity in the methods for estimating RT of one incorporated alpha-cypermethrin and piperonyl butoxide (PBO) and one incorporated permethrin with PBO ITNs was determined using laboratory-reared resistant Anopheles arabiensis under standard laboratory conditions. LM methods and CSM were compared in two experiments with refrigerated nets acclimated for (i) 2 h (test 1) and (ii) 3 h (test 2). Four regeneration replicates per day were tested per ITN product with 50 mosquitoes exposed per replicate (equivalent sample size to LM). The heterogeneity from these methods was compared descriptively. RESULTS The intra-method variability for unwashed pieces was minimal, with variance of 1.26 for CSM and 1.18 for LM. For unwashed nets, LM had substantially greater variance and ratio of LM:CSM was 2.66 in test 1 and 2.49 in test 2. The magnitude of mortality measured in bioassays depended on sample acclimation after refrigeration. CONCLUSIONS The CSM is a convenient method for determining the regeneration times. ITNs are prepared in advance, reducing pressure to prepare all samples to start on a single day. A complete regeneration series of samples is removed from the refrigerator, defrosted and evaluated on a single day with one mosquito batch reducing the influence of mosquito batch heterogeneity on results. Replicates can be conducted over several days but do not have to be conducted on consecutive days, allowing easy facility scheduling.
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Affiliation(s)
- Aidi Galus Lugenge
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania.
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Jilly Jackson Mseti
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
| | - Johnson Kyeba Swai
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | | | - Sarah Jane Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
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Kilpatrick KW, Lee C, Hudgens MG. G-formula for observational studies under stratified interference, with application to bed net use on malaria. Stat Med 2024. [PMID: 38726590 DOI: 10.1002/sim.10102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/22/2024] [Accepted: 04/24/2024] [Indexed: 05/16/2024]
Abstract
Assessing population-level effects of vaccines and other infectious disease prevention measures is important to the field of public health. In infectious disease studies, one person's treatment may affect another individual's outcome, that is, there may be interference between units. For example, the use of bed nets to prevent malaria by one individual may have an indirect effect on other individuals living in close proximity. In some settings, individuals may form groups or clusters where interference only occurs within groups, that is, there is partial interference. Inverse probability weighted estimators have previously been developed for observational studies with partial interference. Unfortunately, these estimators are not well suited for studies with large clusters. Therefore, in this paper, the parametric g-formula is extended to allow for partial interference. G-formula estimators are proposed for overall effects, effects when treated, and effects when untreated. The proposed estimators can accommodate large clusters and do not suffer from the g-null paradox that may occur in the absence of interference. The large sample properties of the proposed estimators are derived assuming no unmeasured confounders and that the partial interference takes a particular form (referred to as 'weak stratified interference'). Simulation studies are presented demonstrating the finite-sample performance of the proposed estimators. The Demographic and Health Survey from the Democratic Republic of the Congo is then analyzed using the proposed g-formula estimators to assess the effects of bed net use on malaria.
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Affiliation(s)
- Kayla W Kilpatrick
- Department of Biostatistics and Bioinformatics, Duke University, Durham, North Carolina
| | - Chanhwa Lee
- Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina
| | - Michael G Hudgens
- Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina
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Odufuwa OG, Bradley J, Ngonyani S, Mpelepele AB, Matanila I, Muganga JB, Bosselmann R, Skovmand O, Mboma ZM, Moore SJ. Time of exposure and assessment influence the mortality induced by insecticides against metabolic resistant mosquitoes. Parasit Vectors 2024; 17:103. [PMID: 38431631 PMCID: PMC10908098 DOI: 10.1186/s13071-024-06190-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/09/2024] [Indexed: 03/05/2024] Open
Abstract
BACKGROUND Increasing metabolic resistance in malaria vector mosquitoes resulted in the development of insecticide-treated nets (ITNs) with active ingredients (AI) that target them. Bioassays that accurately measure the mortality induced by these AIs on ITNs are needed. Mosquito metabolic enzyme expression follows a circadian rhythm. Thus, this study assessed (i) influence of the time of day of mosquito exposure and (ii) timing of assessment of mortality post exposure (24 and 72 h) to ITNs against vectors that are susceptible to pyrethroids and those with metabolic and knockdown resistance mechanisms. METHODS Two cone bioassay experiments were conducted following World Health Organization (WHO) guidelines. Firstly, on ITNs incorporated with 2 g AI/kg of deltamethrin (DM) alone, or combined with 8 g AI/kg piperonyl butoxide (PBO) synergist, during the day (9:00-14:00 h) and repeated in the evening (18:00-20:00 h). This was followed by a confirmatory experiment during the afternoon (12:00-14:00 h) and repeated in the night (22:00-24:00 h) using mosquitoes unexposed or pre-exposed to PBO for 1 h before exposure to DM ITNs. Each net piece was tested with a minimum of eight cones per time (N = 24). The outcome was mortality after 24 h (M24) or 72 h (M72) of holding. RESULTS The cone bioassays performed using metabolic resistant mosquitoes during the evening showed significantly lower M24 than those performed in the day for DM: odds ratio (OR) 0.14 [95% confidence interval (CI) 0.06-0.30, p < 0.0001] and DM PBO [OR 0.29 (95% CI 0.18-0.49, p < 0.0001). M72 was higher than M24 for metabolic resistant mosquitoes exposed to DM [OR 1.44 (95% CI 1.09-1.88), p = 0.009] and DM PBO [OR 1.82 (95% CI 1.42-2.34), p < 0.0001]. An influence of hour of experiment and time of assessment was not observed for mosquitoes that had knockdown resistance or that were pyrethroid-susceptible. CONCLUSIONS Time of day of experiment and hour of assessment of delayed mortality after exposure of mosquitoes are important considerations in evaluating insecticides that interact with mosquito metabolism to counter metabolic resistant mosquitoes. This is important when evaluating field-aged ITNs that may have lower concentrations of AI.
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Affiliation(s)
- Olukayode G Odufuwa
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania.
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Kreuzstrasse 2, Allschwill, 4123, Basel, Switzerland.
- Faculty of Science, University of Basel, Petersplatz 1, 4001, Basel, Switzerland.
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK.
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Safina Ngonyani
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
| | - Ahmadi Bakari Mpelepele
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
| | - Isaya Matanila
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
| | - Joseph B Muganga
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
| | | | | | - Zawadi Mageni Mboma
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), Tengeru, P.O. Box 447, Arusha, Tanzania
| | - Sarah Jane Moore
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Kreuzstrasse 2, Allschwill, 4123, Basel, Switzerland
- Faculty of Science, University of Basel, Petersplatz 1, 4001, Basel, Switzerland
- The Nelson Mandela African Institution of Science and Technology (NM-AIST), Tengeru, P.O. Box 447, Arusha, Tanzania
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Garg S, Gupta V, Patel K, Dewangan M, Nanda P, Sridhar R, Singh G. Assessing afebrile malaria and bed-net use in a high-burden region of India: Findings from multiple rounds of mass screening. PLoS One 2023; 18:e0287667. [PMID: 37467182 DOI: 10.1371/journal.pone.0287667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Accepted: 06/12/2023] [Indexed: 07/21/2023] Open
Abstract
A key obstacle in the fight against malaria is afebrile malaria. It remains undiagnosed and, therefore, is invisible to the health system. Apart from being a serious illness, it contributes to increased transmission. Existing studies in India have not adequately reported afebrile malaria and its determinants, including the use of long-lasting insecticide-treated nets (LLINs). This study used six waves of mass screening, which were conducted by the state government in the high-malaria-burden region of Chhattisgarh, a state in India, in 2020, 2021, and 2022. Each round of data collection included more than 15000 individuals. Descriptive statistics were used to analyse key indicators of malaria prevalence and LLIN use. Multivariate analyses were performed to identify the determinants of afebrile malaria and LLIN use. Malaria prevalence in the afebrile population varied from 0.6% to 1.4% across the different waves of mass screening. In comparison, malaria positivity among febrile individuals was greater than 33% in each wave. Afebrile malaria contributed to 19.6% to 47.2% of the overall malaria burden in the region. Indigenous communities (scheduled tribes) were more susceptible to malaria, including afebrile malaria. Individuals using LLINs were less likely to be affected by afebrile malaria. Overall, 77% of the individuals used LLINs in early monsoon season, and in winter the rate was lower at 55%. LLIN use was significantly associated with the number of LLINs the households received from the government. Although fever continues to be a primary symptom of malaria, afebrile malaria remains a significant contributor to the malaria burden in the region. The free distribution of LLINs should be expanded to include high-burden populations. Global policies must include strategies for surveillance and control of afebrile malaria in high-burden areas.
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Affiliation(s)
- Samir Garg
- Division of Health Systems, State Health Resource Centre, Raipur, Chhattisgarh, India
| | - Vishnu Gupta
- Division of Health Systems, State Health Resource Centre, Raipur, Chhattisgarh, India
| | - Kavita Patel
- Division of Health Systems, State Health Resource Centre, Raipur, Chhattisgarh, India
| | - Mukesh Dewangan
- Division of Health Systems, State Health Resource Centre, Raipur, Chhattisgarh, India
| | - Prabodh Nanda
- Division of Health Systems, State Health Resource Centre, Raipur, Chhattisgarh, India
| | - Ryavanki Sridhar
- Health Section, UNICEF, Chhattisgarh Field Office, Raipur, India
| | - Gajendra Singh
- Health Section, UNICEF, Chhattisgarh Field Office, Raipur, India
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Kabeya TK, Kasongo JCM, Matumba NB, Tshibangu DI, Garcia-Morzon LA, Burgueño E. Impact of mass distribution of long-lasting insecticide nets on the incidence of malaria in Lomami, Democratic Republic of Congo: a study based on electronic health record data (2018 - 2019). Pan Afr Med J 2023; 45:89. [PMID: 37663637 PMCID: PMC10474805 DOI: 10.11604/pamj.2023.45.89.33099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/16/2023] [Indexed: 09/05/2023] Open
Abstract
Introduction holoendemic, malaria remains one of the major public health problems in Lomami Province in the Democratic Republic of Congo (DRC). To fight against it, a free mass distribution of long-lasting insecticide nets (LLINs) was organized in July 2019 throughout the province. The present study aimed to assess the incidence of malaria and its impact on anaemia of children from 0 to 59 months in this region before and after this intervention. Methods we had conducted a retrospective observational study from June to December 2018 and June to December 2019. The data were collected on District Health Information System version two (DHIS2) and analyzed with T-tests to compare the incidence rates before (second semester 2018) and after the distribution of LLINs (second semester 2019). Results the evolution of malaria cases immediately dropped after the distribution campaign. The incidence rates per 1,000 inhabitants in 2018 and 2019 were 106 and 107 respectively in the general population; 302 versus 305 in children aged 0 to 59 months and 219 versus 209 in pregnant women. The differences in incidence were not statistically significant with p values 0.497, 0.4602, and 0.3097 respectively. However, it was observed that the decrease in malaria cases led to a decrease in anaemia cases in general. Conclusion the LLIN distribution campaign did not decrease the incidence of malaria. The synergy of preventive interventions to reduce the incidence of malaria remains key.
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Affiliation(s)
- Theddy Kazadi Kabeya
- School of Public Health, University of Mwene Ditu, Lomami, Democratic Republic of Congo
- Health Regional Division, Kabinda, Lomami, Democratic Republic of Congo
| | - Jean Claude Musasa Kasongo
- School of Public Health, University of Mwene Ditu, Lomami, Democratic Republic of Congo
- Mwene-Ditu Health Zone, Lomami, Democratic Republic of Congo
| | | | | | | | - Eduardo Burgueño
- Centre Médical Vésale, Ngaliema, Kinshasa, Democratic Republic of Congo
- School of Medicine, Official University of Mbujimayi, Kasai-Oriental, Democratic Republic of Congo
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Chilot D, Mondelaers A, Alem AZ, Asres MS, Yimer MA, Toni AT, Ayele TA. Pooled prevalence and risk factors of malaria among children aged 6-59 months in 13 sub-Saharan African countries: A multilevel analysis using recent malaria indicator surveys. PLoS One 2023; 18:e0285265. [PMID: 37256889 DOI: 10.1371/journal.pone.0285265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Accepted: 04/19/2023] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND Every 75 seconds, a child under five dies of malaria. Mainly children, aged between six months and five years, are at the highest risk for malaria. These children lost maternal immunity and did not yet developed specific immunity to the infection. Under the age of five, children bear the highest burden of malaria in Sub-Saharan Africa (SSA). Many individual and community level factors could contribute to malaria prevalence remaining high among under-five children in the region. Thus, this study aimed to assess the pooled prevalence of malaria among children aged 6-59 months and identify potential factors associated with malaria by using recent Malaria Indicator Surveys in 13 SSA countries. METHODS Data for this study were drawn from recent 13 Sub-Saharan African countries Malaria Indicator Surveys (MIS). A total weighted sample of 60,541 children aged 6-59 months was included. STATA version 14.2 was used to clean, code and analyze the data. Multilevel logistic regression was employed to identify factors associated with malaria. Adjusted odds ratio with 95% CI and a P value <0.05 was reported to indicate statistical association. Model fitness and comparison were done using Inter cluster correlation coefficient, Median odds ratio, proportional change in variance, and deviance. RESULTS The pooled prevalence of malaria among children aged 6-59 months was found to be 27.41% (95% CI: 17.94%-36.88%). It ranges from 5.04% in Senegal to 62.57% in Sierra Leone. Aged 36-47 months (AOR = 3.54, 95% CI 3.21-3.91), and 48-59 months (AOR = 4.32, 95% CI 3.91-4.77), mothers attended primary education (AOR = 0.78, 95% CI 0.73-0.84), richer (AOR = 0.35, 95% CI 0.32-0.39), and richest household (AOR = 0.16, 95% CI 0.14-0.19), number of three and more under-five children (AOR = 1.35, 95% CI 1.26-1.45), improved floor material (AOR = 0.65, 95% CI 0.57-0.73), improved wall material (AOR = 0.73, 95% CI 0.64-0.84), improved roof material (AOR = 0.70, 95% CI 0.51-0.93), insecticide-treated bed net (ITN) use (0.56, 95% CI 0.51-0.62), not anemic (AOR = 0.05, 95% CI 0.04-0.06), rural resident (AOR = 2.16, 95% CI 2.06-2.27), high community ITN use (AOR = 0.40, 95% CI 0.24-0.63) and high community poverty (AOR = 2.66, 95% CI 2.53-2.84) were strongly associated with malaria. CONCLUSIONS AND RECOMMENDATIONS Almost 3 out of 10 children were infected by malaria in 13 SSA countries. Malaria infection remains one of the main killers of children aged 6-59 months in the SSA. This study revealed that older under-five children living in large families with low incomes in rural areas are most vulnerable to malaria infection. Our results clearly indicate that ITN utilization and improved housing are promising means to effectively prevent malaria infection among children aged 6-59 months. It is therefore important to note that households with low wealth quintiles and rural residents should be prioritized in any mass distribution of ITNs. This has to be accompanied by education using mass media to enhance community awareness.
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Affiliation(s)
- Dagmawi Chilot
- Department of Human Physiology, University of Gondar, College of Medicine and Health Science, School of Medicine, Gondar, Ethiopia
| | - Annelies Mondelaers
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Adugnaw Zeleke Alem
- Department of Epidemiology & Biostatistics, Institute of Public Health, University of Gondar, College of Medicine and Health Science, Gondar, Ethiopia
| | - Mezgebu Selamsew Asres
- Department of Internal Medicine, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Mulugeta Ayalew Yimer
- Department of Pediatrics and Child Health, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Alemayehu Teklu Toni
- Department of Pediatrics and Child Health, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia
| | - Tadesse Awoke Ayele
- Department of Epidemiology & Biostatistics, Institute of Public Health, University of Gondar, College of Medicine and Health Science, Gondar, Ethiopia
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Topazian HM, Schmit N, Gerard-Ursin I, Charles GD, Thompson H, Ghani AC, Winskill P. Modelling the relative cost-effectiveness of the RTS,S/AS01 malaria vaccine compared to investment in vector control or chemoprophylaxis. Vaccine 2023; 41:3215-3223. [PMID: 37080831 DOI: 10.1016/j.vaccine.2023.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 04/03/2023] [Accepted: 04/03/2023] [Indexed: 04/22/2023]
Abstract
BACKGROUND The World Health Organization has recommended a 4-dose schedule of the RTS,S/AS01 (RTS,S) vaccine for children in regions of moderate to high P. falciparum transmission. Faced with limited supply and finite resources, global funders and domestic malaria control programs will need to examine the relative cost-effectiveness of RTS,S and identify target areas for vaccine implementation relative to scale-up of existing interventions. METHODS Using an individual-based mathematical model of P. falciparum, we modelled the cost-effectiveness of RTS,S across a range of settings in sub-Saharan Africa, incorporating various rainfall patterns, insecticide-treated net (ITN) use, treatment coverage, and parasite prevalence bands. We compare age-based and seasonal RTS,S administration to increasing ITN usage, switching to next generation ITNs in settings experiencing insecticide-resistance, and introduction of seasonal malaria chemoprevention (SMC) in areas of seasonal transmission. RESULTS For RTS,S to be the most cost-effective intervention option considered, the maximum cost per dose was less than $9.30 USD in 90.9% of scenarios. Nearly all (89.8%) values at or above $9.30 USD per dose were in settings with 60% established bed net use and / or with established SMC, and 76.3% were in the highest PfPR2-10 band modelled (40%). Addition of RTS,S to strategies involving 60% ITN use, increased ITN usage or a switch to PBO nets, and SMC, if eligible, still led to significant marginal case reductions, with a median of 2,653 (IQR: 1,741 to 3,966) cases averted per 100,000 people annually, and 82,270 (IQR: 54,034 to 123,105) cases averted per 100,000 fully vaccinated children (receiving at least three doses). CONCLUSIONS Use of RTS,S results in reductions in malaria cases and deaths even when layered upon existing interventions. When comparing relative cost-effectiveness, scale up of ITNs, introduction of SMC, and switching to new technology nets should be prioritized in eligible settings.
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Affiliation(s)
- Hillary M Topazian
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK.
| | - Nora Schmit
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Ines Gerard-Ursin
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Giovanni D Charles
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Hayley Thompson
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
| | - Peter Winskill
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, UK
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Sarfo JO, Amoadu M, Kordorwu PY, Adams AK, Gyan TB, Osman AG, Asiedu I, Ansah EW. Malaria amongst children under five in sub-Saharan Africa: a scoping review of prevalence, risk factors and preventive interventions. Eur J Med Res 2023; 28:80. [PMID: 36800986 PMCID: PMC9936673 DOI: 10.1186/s40001-023-01046-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 02/06/2023] [Indexed: 02/19/2023] Open
Abstract
INTRODUCTION Africa has a higher burden of malaria-related cases and deaths globally. Children under five accounted for over two-thirds of all malaria deaths in sub-Saharan Africa (SSA). This scoping review aims to map evidence of the prevalence, contextual factors and health education interventions of malaria amongst children under 5 years (UN5) in SSA. METHOD Four main databases (PubMed, Central, Dimensions and JSTOR) produced 27,841 records of literature. Additional searches in Google, Google Scholar and institutional repositories produced 37 records. Finally, 255 full-text records were further screened, and 100 records were used for this review. RESULTS Low or no formal education, poverty or low income and rural areas are risk factors for malaria amongst UN5. Evidence on age and malnutrition as risk factors for malaria in UN5 is inconsistent and inconclusive. Furthermore, the poor housing system in SSA and the unavailability of electricity in rural areas and unclean water make UN5 more susceptible to malaria. Health education and promotion interventions have significantly reduced the malaria burden on UN5 in SSA. CONCLUSION Well-planned and resourced health education and promotion interventions that focus on prevention, testing and treatment of malaria could reduce malaria burden amongst UN5 in SSA.
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Affiliation(s)
- Jacob Owusu Sarfo
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
| | | | - Peace Yaa Kordorwu
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
| | - Abdul Karim Adams
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
| | | | - Abdul-Ganiyu Osman
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
| | - Immanuel Asiedu
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
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Malaria profile and socioeconomic predictors among under-five children: an analysis of 11 sub-Saharan African countries. Malar J 2023; 22:55. [PMID: 36788541 PMCID: PMC9927033 DOI: 10.1186/s12936-023-04484-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
Abstract
BACKGROUND African region accounts for 95% of all malaria cases and 96% of malaria deaths with under-five children accounting for 80% of all deaths in the region. This study assessed the socioeconomic determinants of malaria prevalence and provide evidence on the socioeconomic profile of malaria infection among under-five children in 11 SSA countries. METHODS This study used data from the 2010 to 2020 Demographic and Health Survey (DHS). The survey used a two-stage stratified-cluster sampling design based on the sampling frame of the population and housing census of countries included. Statistical analyses relied on Pearson's χ2, using the CHAID decision-tree algorithm and logistic regression implemented in R V.4.6. RESULTS Of 8547 children considered, 24.2% (95% confidence interval CI 23.4-25.05%) had malaria infection. Also, the prevalence of malaria infection seems to increase with age. The following variables are statistically associated with the prevalence of malaria infection among under-five children: under-five child's age, maternal education, sex of household head, household wealth index, place of residence, and African region where mother-child pair lives. Children whose mothers have secondary education have about 56% lower risk (odds ratio = 0.44; 95% CI 0.40-0.48) of malaria infection and 73% lower (odds ratio = 0.37; 95% CI 0.32-0.43) among children living in the richest households, compared to children living in the poorest households. CONCLUSIONS The findings of this study provide unique insights on how socioeconomic and demographic variables, especially maternal education level significantly predicts under-five malaria prevalence across the SSA region. Therefore, ensuring that malaria interventions are underpinned by a multisectoral approach that comprehensively tackles the interplay of maternal education and other socioeconomic variables will be critical in attaining malaria prevention and control targets in SSA.
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Ilombe G, Matangila JR, Lulebo A, Mutombo P, Linsuke S, Maketa V, Mabanzila B, Wat’senga F, Van Bortel W, Fiacre A, Irish SR, Lutumba P, Van Geertruyden JP. Malaria among children under 10 years in 4 endemic health areas in Kisantu Health Zone: epidemiology and transmission. Malar J 2023; 22:3. [PMID: 36604663 PMCID: PMC9814333 DOI: 10.1186/s12936-022-04415-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 12/14/2022] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The Democratic Republic of the Congo (DRC) is the second most malaria-affected country in the world with 21,608,681 cases reported in 2019. The Kongo Central (KC) Province has a malaria annual incidence of 163 cases/per 1000 inhabitants which are close to the national average of 153.4/1000. However, the malaria prevalence varies both between and within health zones in this province. The main objective of this study was to describe the epidemiology and transmission of malaria among children aged 0 to 10 years in the 4 highest endemic health areas in Kisantu Health Zone (HZ) of KC in DRC. METHODS A community-based cross-sectional study was conducted from October to November 2017 using multi-stage sampling. A total of 30 villages in 4 health areas in Kisantu HZ were randomly selected. The prevalence of malaria was measured using a thick blood smear (TBS) and known predictors and associated outcomes were assessed. Data are described and association determinants of malaria infection were analysed. RESULTS A total of 1790 children between 0 and 10 years were included in 30 villages in 4 health areas of Kisantu HZ. The overall prevalence in the study area according to the TBS was 14.8% (95% CI: 13.8-16.6; range: 0-53). The mean sporozoite rate in the study area was 4.3% (95% CI: 2.6-6.6). The determination of kdr-west resistance alleles showed the presence of both L1014S and L1014F with 14.6% heterozygous L1014S/L1014F, 84.4% homozygous 1014F, and 1% homozygous 1014S. The risk factors associated with malaria infection were ground or wooden floors aOR: 15.8 (95% CI: 8.6-29.2), a moderate or severe underweight: 1.5 (1.1-2.3) and to be overweight: 1.9 (95% CI: 1.3-2.7). CONCLUSION Malaria prevalence differed between villages and health areas within the same health zone. The control strategy activities must be oriented by the variety in the prevalence and transmission of malaria in different areas. The policy against malaria regarding long-lasting insecticidal nets should be based on the evidence of metabolic resistance.
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Affiliation(s)
- Gillon Ilombe
- grid.452637.10000 0004 0580 7727Unit of Entomology, Department of Parasitology, National Institute of Biomedical Research, Kinshasa, Democratic Republic of the Congo ,grid.9783.50000 0000 9927 0991Unit of Clinical Pharmacology and Pharmacovigilance, Department of Base Science, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of the Congo ,grid.5284.b0000 0001 0790 3681Global Health Institute, Antwerp University, Antwerp, Belgium
| | - Junior Rika Matangila
- grid.9783.50000 0000 9927 0991Department of Tropical Medicine, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Aimee Lulebo
- grid.9783.50000 0000 9927 0991Faculty of Medicine, Public Health School, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Paulin Mutombo
- grid.9783.50000 0000 9927 0991Faculty of Medicine, Public Health School, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Sylvie Linsuke
- grid.5284.b0000 0001 0790 3681Global Health Institute, Antwerp University, Antwerp, Belgium ,grid.452637.10000 0004 0580 7727Department of Epidemiology Kinshasa, National Institute of Biomedical Research, Kinshasa, Democratic Republic of the Congo
| | - Vivi Maketa
- grid.9783.50000 0000 9927 0991Department of Tropical Medicine, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Baby Mabanzila
- grid.9783.50000 0000 9927 0991Department of Tropical Medicine, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Francis Wat’senga
- grid.452637.10000 0004 0580 7727Unit of Entomology, Department of Parasitology, National Institute of Biomedical Research, Kinshasa, Democratic Republic of the Congo
| | - Wim Van Bortel
- grid.11505.300000 0001 2153 5088Unit of Entomology and Outbreak Research Team, Unit of Entomology, Institute of Tropical Medicine, Antwerp, Belgium
| | - Agossa Fiacre
- PMI VectorLink Project, Abt Associates, Kinshasa, Democratic Republic of the Congo
| | - Seth R. Irish
- grid.467642.50000 0004 0540 3132Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, President’s Malaria Initiative and Entomology Branch, Atlanta, GA USA
| | - Pascal Lutumba
- grid.9783.50000 0000 9927 0991Department of Tropical Medicine, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
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Ideational factors and their association with insecticide treated net use in Magoe District, Mozambique. Malar J 2022; 21:387. [PMID: 36528569 PMCID: PMC9758899 DOI: 10.1186/s12936-022-04405-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Insecticide treated bed nets (ITN) are considered a core malaria vector control tool by the WHO and are the main contributor to the large decline in malaria burden in sub-Saharan Africa over the past 20 years, but they are less effective if they are not broadly and regularly used. ITN use may depend on factors including temperature, relative humidity, mosquito density, seasonality, as well as ideational or psychosocial factors including perceptions of nets and perceptions of net use behaviours. METHODS A cross-sectional household survey was conducted as part of a planned randomized controlled trial in Magoe District, Mozambique. Interviewers captured data on general malaria and ITN perceptions including ideational factors related to perceived ITN response efficacy, self-efficacy to use an ITN, and community norms around ITN using a standardized questionnaire. Only households with sufficient ITNs present for all children to sleep under (at least one ITN for every two children under the age of five years) were eligible for inclusion in the study. Additional questions were added about seasonality and frequency of ITN use. RESULTS One-thousand six hundred sixteen mother-child dyads were interviewed. Responses indicated gaps in use of existing nets and net use was largely independent of ideational factors related to ITNs. Self-reported ITN use varied little by season nor meaningfully when different methods were used to solicit responses on net use behaviour. Mothers' perceived response efficacy of ITNS was negatively associated with net use (high perceived response efficacy reduced the log-odds of net use by 0.27 (95% CI - 0.04 to - 0.51), implying that stronger beliefs in the effectiveness of ITNs might result in reduced net use among their children. CONCLUSIONS In this context, ITN use among children was not clearly related to mothers' ideational factors measured in the study. Scales used in solicitation of ideation around ITN use and beliefs need careful design and testing across a broader range of populations in order to identify ideational factors related to ITN use among those with access.
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Bubun N, Anetul E, Koinari M, Freeman TW, Karl S. Coating formulation change leads to inferior performance of long-lasting insecticidal nets in Papua New Guinea. Malar J 2022; 21:349. [PMID: 36424604 PMCID: PMC9685832 DOI: 10.1186/s12936-022-04392-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 11/17/2022] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) play a key role in reducing malaria transmission in endemic countries. In a previous study, the authors demonstrated a substantial decrease in the bioefficacy of LLINs for malaria prevention delivered to Papua New Guinea (PNG) between 2013 and 2019. This coincided with a rise in malaria cases in the country. The present study was aimed at determining the underlying cause of the reduced bioefficacy observed in these LLINs. The main hypothesis was that a change in the coating formulation of the respective LLIN product was responsible, and had led to significantly altered product properties and performance. METHODS A set of PermaNet® 2.0 LLIN samples (n = 12) manufactured between 2007 and 2019 was subjected to combustion ion chromatography in order to understand the chemistry of the LLIN polymer coating formulation. In addition, World Health Organization (WHO) LLIN standard wash tests and cone bioassays were conducted to further characterize the change in product performance that occurred between 2012 and 2013. RESULTS High polymer fluorine content (average 3.2 g/kg) was measured in PermaNet® 2.0 manufactured up to 2012, whereas nets which were manufactured after 2012 contained very little polymer fluorine (average 0.04 g/kg) indicating a coating formulation change from a fluorocarbon (FC)-based to a non-FC-based formulation. The coating formulation change as part of the manufacturing process thus resulted in a significant reduction in bioefficacy. In addition, the manufacturing change affected wash resistance leading to a faster reduction in 24 h mosquito mortality in the non-FC-coated product with consecutive washes. CONCLUSION A change in coating formulation of PermaNet® 2.0 resulted in reduced product performance in PNG. Post-2012 PermaNet® 2.0 LLINs should not be considered to be the same product as PermaNet® 2.0 LLINs produced prior to and in 2012. Coating formulation changes should be validated to not impact LLIN product performance.
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Affiliation(s)
- Nakei Bubun
- grid.417153.50000 0001 2288 2831Vector-Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Madang Province Papua New Guinea
| | - Evodia Anetul
- grid.417153.50000 0001 2288 2831Vector-Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Madang Province Papua New Guinea
| | - Melanie Koinari
- grid.1011.10000 0004 0474 1797Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD Australia
| | - Timothy W. Freeman
- Rotarians Against Malaria Papua New Guinea, Port Moresby, National Capital District, Papua New Guinea
| | - Stephan Karl
- grid.417153.50000 0001 2288 2831Vector-Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Madang Province Papua New Guinea ,grid.1011.10000 0004 0474 1797Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, QLD Australia
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Malaria among under-five children in Ethiopia: a systematic review and meta-analysis. Malar J 2022; 21:338. [PMID: 36384533 PMCID: PMC9667600 DOI: 10.1186/s12936-022-04370-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 11/07/2022] [Indexed: 11/17/2022] Open
Abstract
Background Globally, malaria is among the leading cause of under-five mortality and morbidity. Despite various malaria elimination strategies being implemented in the last decades, malaria remains a major public health concern, particularly in tropical and sub-tropical regions. Furthermore, there have been limited and inconclusive studies in Ethiopia to generate information for action towards malaria in under-five children. Additionally, there is a considerable disparity between the results of the existing studies. Therefore, the pooled estimate from this study will provide a more conclusive result to take evidence-based interventional measures against under-five malaria. Methods The protocol of this review is registered at PROSPERO with registration number CRD42020157886. All appropriate databases and grey literature were searched to find relevant articles. Studies reporting the prevalence or risk factors of malaria among under-five children were included. The quality of each study was assessed using the Newcastle–Ottawa Quality Assessment Scale (NOS). Data was extracted using Microsoft Excel 2016 and analysis was done using STATA 16.0 statistical software. The pooled prevalence and its associated factors of malaria were determined using a random effect model. Heterogeneity between studies was assessed using the Cochrane Q-test statistics and I2 test. Furthermore, publication bias was checked by the visual inspection of the funnel plot and using Egger’s and Begg’s statistical tests. Results Twelve studies with 34,842 under-five children were included. The pooled prevalence of under-five malaria was 22.03% (95% CI 12.25%, 31.80%). Lack of insecticide-treated mosquito net utilization (AOR: 5.67, 95% CI 3.6, 7.74), poor knowledge of child caretakers towards malaria transmission (AOR: 2.79, 95% CI 1.70, 3.89), and living near mosquito breeding sites (AOR: 5.05, 95% CI 2.92, 7.19) were risk factors of under-five malaria. Conclusion More than one in five children aged under five years were infected with malaria. This suggests the rate of under-five malaria is far off the 2030 national malaria elimination programme of Ethiopia. The Government should strengthen malaria control strategies such as disseminating insecticide-treated mosquito nets (ITNs), advocating the utilization of ITNs, and raising community awareness regarding malaria transmission. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04370-9.
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It Is Time to Strengthen the Malaria Control Policy of the Democratic Republic of Congo and Include Schools and School-Age Children in Malaria Control Measures. Pathogens 2022; 11:pathogens11070729. [PMID: 35889975 PMCID: PMC9315856 DOI: 10.3390/pathogens11070729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 06/22/2022] [Accepted: 06/24/2022] [Indexed: 02/04/2023] Open
Abstract
Despite a decade of sustained malaria control, malaria remains a serious public health problem in the Democratic Republic of Congo (DRC). Children under five years of age and school-age children aged 5–15 years remain at high risk of symptomatic and asymptomatic malaria infections. The World Health Organization’s malaria control, elimination, and eradication recommendations are still only partially implemented in DRC. For better malaria control and eventual elimination, the integration of all individuals into the national malaria control programme will strengthen malaria control and elimination strategies in the country. Thus, inclusion of schools and school-age children in DRC malaria control interventions is needed.
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Lusiyana N, Ahdika A. Evaluating recurrent episodes of malaria incidence in Timika, Indonesia, through a Markovian multiple-state model. Infect Dis Model 2022; 7:261-276. [PMID: 35754556 PMCID: PMC9201011 DOI: 10.1016/j.idm.2022.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 03/30/2022] [Accepted: 05/31/2022] [Indexed: 10/27/2022] Open
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Brozak SJ, Mohammed-Awel J, Gumel AB. Mathematics of a single-locus model for assessing the impacts of pyrethroid resistance and temperature on population abundance of malaria mosquitoes. Infect Dis Model 2022; 7:277-316. [PMID: 35782338 PMCID: PMC9234087 DOI: 10.1016/j.idm.2022.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/25/2022] [Accepted: 05/25/2022] [Indexed: 11/18/2022] Open
Abstract
This study presents a genetic-ecology modeling framework for assessing the combined impacts of insecticide resistance, temperature variability, and insecticide-based interventions on the population abundance and control of malaria mosquitoes by genotype. Rigorous analyses of the model we developed reveal that the boundary equilibrium with only mosquitoes of homozygous sensitive (resistant) genotype is locally-asymptotically stable whenever a certain ecological threshold, denoted by R0SS(R0RR), is less than one. Furthermore, genotype i drives genotype j to extinction whenever R0j>1 and R0i<1 (where i, j = SS or RR, with i ≠ j). The model exhibits the phenomenon of bistability when both thresholds are less than one. In such a bistable situation, convergence to any of the two boundary equilibria depends on the initial allele distribution in the state variables of the model. Furthermore, in this bistable case, where max{R0SS,R0RR}<1, the basin of attraction of the boundary equilibrium of the mosquito genotype with lower value of the ecological threshold is larger. Specifically, the basin of attraction of the boundary equilibrium for genotype i is larger than that of genotype j if R0i<R0j<1. When both ecological thresholds exceed one (min{R0SS,R0RR}>1), the two boundary equilibria lose their stability, and a coexistence equilibrium (where all three mosquito genotypes coexist) becomes locally-asymptotically stable. Global sensitivity analysis shows that the key parameters that greatly influence the dynamics and population abundance of resistant mosquitoes include the proportion of new adult mosquitoes that are females, the insecticide-induced mortality rate of adult female mosquitoes, the coverage level and efficacy of adulticides used in the community, the oviposition rates for eggs of heterozygous and homozygous resistant genotypes, and the modification parameter accounting for the reduction in insecticide-induced mortality due to resistance. Numerical simulations show that the adult mosquito population increases with increasing temperature until a peak is reached at 31 °C, and declines thereafter. Simulating the model for moderate and high adulticide coverage, together with varying fitness costs of resistance, shows a switch in the dominant genotype at equilibrium as temperature is varied. In other words, this study shows that, for certain combinations of adulticide coverage and fitness costs of insecticide resistance, increases in temperature could result in effective management of resistance (by causing the switch from a stable resistant-only boundary equilibrium (at 18 °C) to a stable sensitive-only boundary equilibrium (at 25 °C)). Finally, this study shows that, for moderate fitness costs of resistance, density-dependent larval mortality suppresses the total population of adult mosquitoes with the resistant allele for all temperature values in the range [18 °C–36 °C].
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Affiliation(s)
- Samantha J. Brozak
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Jemal Mohammed-Awel
- Department of Mathematics, Morgan State University, Baltimore, MD, 21251, USA
| | - Abba B. Gumel
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
- Department of Mathematics and Applied Mathematics, University of Pretoria, Pretoria, 0002, South Africa
- Corresponding author. School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, 85287, USA.
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Fink G, Mrema S, Abdulla S, Kachur SP, Khatib R, Lengeler C, Masanja H, Okumu F, Schellenberg J. Mosquito Net Use in Early Childhood and Survival to Adulthood in Tanzania. N Engl J Med 2022; 386:428-436. [PMID: 35108469 DOI: 10.1056/nejmoa2112524] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND It has been hypothesized that in high-transmission settings, malaria control in early childhood (<5 years of age) might delay the acquisition of functional immunity and shift child deaths from younger to older ages. METHODS We used data from a 22-year prospective cohort study in rural southern Tanzania to estimate the association between early-life use of treated nets and survival to adulthood. All the children born between January 1, 1998, and August 30, 2000, in the study area were invited to enroll in a longitudinal study from 1998 through 2003. Adult survival outcomes were verified in 2019 through community outreach and mobile telephones. We used Cox proportional-hazards models to estimate the association between the use of treated nets in early childhood and survival to adulthood, adjusting for potential confounders. RESULTS A total of 6706 children were enrolled. In 2019, we verified information on the vital status of 5983 participants (89%). According to reports of early-life community outreach visits, approximately one quarter of children never slept under a treated net, one half slept under a treated net some of the time, and the remaining quarter always slept under a treated net. Participants who were reported to have used treated nets at half the early-life visits or more had a hazard ratio for death of 0.57 (95% confidence interval [CI], 0.45 to 0.72) as compared with those who were reported to have used treated nets at less than half the visits. The corresponding hazard ratio between 5 years of age and adulthood was 0.93 (95% CI, 0.58 to 1.49). CONCLUSIONS In this long-term study of early-life malaria control in a high-transmission setting, the survival benefit from early-life use of treated nets persisted to adulthood. (Funded by the Eckenstein-Geigy Professorship and others.).
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Affiliation(s)
- Günther Fink
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
| | - Sigilbert Mrema
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
| | - Salim Abdulla
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
| | - S Patrick Kachur
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
| | - Rashid Khatib
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
| | - Christian Lengeler
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
| | - Honorati Masanja
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
| | - Fredros Okumu
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
| | - Joanna Schellenberg
- From the Swiss Tropical and Public Health Institute and the University of Basel, Basel, Switzerland (G.F., C.L.); Ifakara Health Institute, Dar es Salaam, Tanzania (S.M., S.A., R.K., H.M., F.O.); Mailman School of Public Health, Columbia University, New York (S.P.K.); and the London School of Hygiene and Tropical Medicine, London (J.S.)
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Ngufor C, Fagbohoun J, Agbevo A, Ismail H, Challenger JD, Churcher TS, Rowland M. Comparative efficacy of two pyrethroid-piperonyl butoxide nets (Olyset Plus and PermaNet 3.0) against pyrethroid resistant malaria vectors: a non-inferiority assessment. Malar J 2022; 21:20. [PMID: 35016676 PMCID: PMC8753866 DOI: 10.1186/s12936-022-04041-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 01/03/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pyrethroid-PBO nets were conditionally recommended for control of malaria transmitted by mosquitoes with oxidase-based pyrethroid-resistance based on epidemiological evidence of additional protective effect with Olyset Plus compared to a pyrethroid-only net (Olyset Net). Entomological studies can be used to assess the comparative performance of other brands of pyrethroid-PBO ITNs to Olyset Plus. METHODS An experimental hut trial was performed in Cové, Benin to compare PermaNet 3.0 (deltamethrin plus PBO on roof panel only) to Olyset Plus (permethrin plus PBO on all panels) against wild pyrethroid-resistant Anopheles gambiae sensu lato (s.l.) following World Health Organization (WHO) guidelines. Both nets were tested unwashed and after 20 standardized washes compared to Olyset Net. Laboratory bioassays were also performed to help explain findings in the experimental huts. RESULTS With unwashed nets, mosquito mortality was higher in huts with PermaNet 3.0 compared to Olyset Plus (41% vs. 28%, P < 0.001). After 20 washes, mortality declined significantly with PermaNet 3.0 (41% unwashed vs. 17% after washing P < 0.001), but not with Olyset Plus (28% unwashed vs. 24% after washing P = 0.433); Olyset Plus induced significantly higher mortality than PermaNet 3.0 and Olyset Net after 20 washes. PermaNet 3.0 showed a higher wash retention of PBO compared to Olyset Plus. A non-inferiority analysis performed with data from unwashed and washed nets together using a margin recommended by the WHO, showed that PermaNet 3.0 was non-inferior to Olyset Plus in terms of mosquito mortality (25% with Olyset Plus vs. 27% with PermaNet 3.0, OR = 1.528, 95%CI = 1.02-2.29) but not in reducing mosquito feeding (25% with Olyset Plus vs. 30% with PermaNet 3.0, OR = 1.192, 95%CI = 0.77-1.84). Both pyrethroid-PBO nets were superior to Olyset Net. CONCLUSION Olyset Plus outperformed PermaNet 3.0 in terms of its ability to cause greater margins of improved mosquito mortality compared to a standard pyrethroid net, after multiple standardized washes. However, using a margin of non-inferiority defined by the WHO, PermaNet 3.0 was non-inferior to Olyset Plus in inducing mosquito mortality. Considering the low levels of mortality observed and increasing pyrethroid-resistance in West Africa, it is unclear whether either of these nets would demonstrate the same epidemiological impact observed in community trials in East Africa.
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Affiliation(s)
- Corine Ngufor
- London School of Hygiene and Tropical Medicine (LSHTM), London, UK. .,Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin. .,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
| | - Josias Fagbohoun
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin ,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Abel Agbevo
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin ,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Hanafy Ismail
- grid.48004.380000 0004 1936 9764Liverpool School of Tropical Medicine, Liverpool, L3 5QA UK
| | - Joseph D. Challenger
- grid.7445.20000 0001 2113 8111MRC Centre for Global Infectious Disease Analysis, Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG UK
| | - Thomas S. Churcher
- grid.7445.20000 0001 2113 8111MRC Centre for Global Infectious Disease Analysis, Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG UK
| | - Mark Rowland
- grid.8991.90000 0004 0425 469XLondon School of Hygiene and Tropical Medicine (LSHTM), London, UK ,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
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Bandibabone J, McLoughlin C, N'Do S, Bantuzeko C, Byabushi V, Jeanberckmans M, Guardiola M, Zawadi B, Diabaté A, Prudhomme J, Walker T, Messenger LA. Investigating molecular mechanisms of insecticide resistance in the Eastern Democratic Republic of the Congo. Malar J 2021; 20:464. [PMID: 34906124 PMCID: PMC8670120 DOI: 10.1186/s12936-021-04002-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/01/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria vector control in the Democratic Republic of the Congo is plagued by several major challenges, including inadequate infrastructure, lack of access to health care systems and preventative measures, and more recently the widespread emergence of insecticide resistance among Anopheles mosquitoes. Across 26 provinces, insecticide resistance has been reported from multiple sentinel sites. However, to date, investigation of molecular resistance mechanisms among Anopheles vector populations in DRC has been more limited. METHODS Adult Anopheles gambiae sensu lato (s.l.) and Anopheles funestus s.l. were collected from two sites in Sud-Kivu province and one site in Haut-Uélé province and PCR-screened for the presence of 11 resistance mutations, to provide additional information on frequency of resistance mechanisms in the eastern DRC, and to critically evaluate the utility of these markers for prospective country-wide resistance monitoring. RESULTS L1014F-kdr and L1014S-kdr were present in 75.9% and 56.7% of An. gambiae s.l. screened, respectively, with some individuals harbouring both resistant alleles. Across the three study sites, L43F-CYP4J5 allele frequency ranged from 0.42 to 0.52, with evidence for ongoing selection. G119S-ace1 was also identified in all sites but at lower levels. A triple mutant haplotype (comprising the point mutation CYP6P4-I236M, the insertion of a partial Zanzibar-like transposable element and duplication of CYP6AA1) was present at high frequencies. In An. funestus s.l. cis-regulatory polymorphisms in CYP6P9a and CYP6P9b were detected, with allele frequencies ranging from 0.82 to 0.98 and 0.65 to 0.83, respectively. CONCLUSIONS This study screened the most up-to-date panel of DNA-based resistance markers in An. gambiae s.l. and An. funestus s.l. from the eastern DRC, where resistance data is lacking. Several new candidate markers (CYP4J5, G119S-ace1, the triple mutant, CYP6P9a and CYP6P9b) were identified, which are diagnostic of resistance to major insecticide classes, and warrant future, larger-scale monitoring in the DRC to inform vector control decisions by the National Malaria Control Programme.
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Affiliation(s)
- Janvier Bandibabone
- Laboratoire d'Entomologie Médicale et Parasitologie, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud-Kivu, Democratic Republic of the Congo
| | - Charles McLoughlin
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Sévérin N'Do
- Médecins Sans Frontières (MSF) OCBA, Barcelona, Spain
- Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
- Institut de Recherche en Sciences de la Santé (IRSS)/Centre MURAZ, Bobo-Dioulasso, Burkina Faso
| | - Chimanuka Bantuzeko
- Laboratoire d'Entomologie Médicale et Parasitologie, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud-Kivu, Democratic Republic of the Congo
- Université Officielle de Bukavu, Bukavu, Democratic Republic of the Congo
| | - Vital Byabushi
- Kibali Gold Mine, Haut-Uele, Democratic Republic of the Congo
| | | | | | - Bertin Zawadi
- Laboratoire d'Entomologie Médicale et Parasitologie, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Sud-Kivu, Democratic Republic of the Congo
| | | | - Jorian Prudhomme
- Médecins Sans Frontières (MSF) OCBA, Barcelona, Spain
- UMR MIVEGEC (IRD-CNRS - Université de Montpellier), 911 Avenue Agropolis, 34394, Montpellier, France
| | - Thomas Walker
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Louisa A Messenger
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
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21
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Metelo-Matubi E, Zanga J, Binene G, Mvuama N, Ngamukie S, Nkey J, Schopp P, Bamba M, Irish S, Nguya-Kalemba-Maniania J, Fasine S, Nagahuedi J, Muyembe JJ, Mansiangi P. The effect of a mass distribution of insecticide-treated nets on insecticide resistance and entomological inoculation rates of Anopheles gambiae s.l. in Bandundu City, Democratic Repub`lic of Congo. Pan Afr Med J 2021; 40:118. [PMID: 34887992 PMCID: PMC8627145 DOI: 10.11604/pamj.2021.40.118.27365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 10/10/2021] [Indexed: 11/26/2022] Open
Abstract
Introduction insecticide-treated nets (ITNs) remain the mainstay of malaria vector control in the Democratic Republic of Congo. However, insecticide resistance of malaria vectors threatens their effectiveness. Entomological inoculation rates and insecticide susceptibility in Anopheles gambiae s.l. were evaluated before and after mass distribution of ITNs in Bandundu City for possible occurrence of resistance. Methods a cross-sectional study was conducted from 15th July 2015 to 15th June 2016. Adult mosquitoes were collected using pyrethrum spray catches and human landing catches and identified to species level and tested for the presence of sporozoites. Bioassays were carried out before and after distribution of ITNs to assess the susceptibility of adult mosquitoes to insecticides. Synergist bioassays were also conducted and target site mutations assessed using Polymerase chain reaction (PCR). Results a total of 1754 female An. gambiae s.l. were collected before and after deployment of ITNs. Fewer mosquitoes were collected after the distribution of ITNs. However, there was no significant difference in sporozoite rates or the overall entomological inoculation rate before and after the distribution of ITNs. Test-mosquitoes were resistant to deltamethrin, permethrin, and Dichlorodiphenyltrichloroethane but susceptible to bendiocarb. Pre-exposure of mosquitoes to Piperonyl butoxide increased their mortality after exposure to permethrin and deltamethrin. The frequency of the Kinase insert domain receptor (kdr)-West gene increased from 92 to 99% before and after the distribution of nets, respectively. Conclusion seasonal impacts could be a limiting factor in the analysis of these data; however, the lack of decrease in transmission after the distribution of new nets could be explained by the high-level of resistance to pyrethroid.
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Affiliation(s)
- Emery Metelo-Matubi
- Faculté de Médecine, Université de Bandundu, B.P 548 Bandundu-ville, Bandundu, République Démocratique de Congo.,Institut National de Recherche Biomédicale, B.P 1197 KIN 1, Kinshasa, République Démocratique de Congo.,Faculté des Sciences, Département de Biologie, Unité de Recherche Entomologique, B.P 190 KIN XI, Université de Kinshasa, Kinshasa, République Démocratique de Congo
| | - Josué Zanga
- Faculté de Médecine, Ecole de Santé Publique, Département de Santé Environnementale, B.P 834 KIN XI, Université de Kinshasa, Kinshasa, République Démocratique de Congo
| | - Guillaume Binene
- Institut National de Recherche Biomédicale, B.P 1197 KIN 1, Kinshasa, République Démocratique de Congo
| | - Nono Mvuama
- Faculté de Médecine, Ecole de Santé Publique, Département de Santé Environnementale, B.P 834 KIN XI, Université de Kinshasa, Kinshasa, République Démocratique de Congo
| | - Solange Ngamukie
- Faculté de Médecine, Ecole de Santé Publique, Département de Santé Environnementale, B.P 834 KIN XI, Université de Kinshasa, Kinshasa, République Démocratique de Congo
| | - Jadis Nkey
- Faculté de Médecine, Université de Bandundu, B.P 548 Bandundu-ville, Bandundu, République Démocratique de Congo
| | - Pauline Schopp
- United States President´s Malaria Initiative and Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30329, USA
| | - Maxwell Bamba
- Faculté de Médecine, Ecole de Santé Publique, Département de Santé Environnementale, B.P 834 KIN XI, Université de Kinshasa, Kinshasa, République Démocratique de Congo
| | - Seth Irish
- United States President´s Malaria Initiative and Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30329, USA
| | | | - Sylvie Fasine
- Institut National de Recherche Biomédicale, B.P 1197 KIN 1, Kinshasa, République Démocratique de Congo
| | - Jonas Nagahuedi
- Faculté des Sciences, Département de Biologie, Unité de Recherche Entomologique, B.P 190 KIN XI, Université de Kinshasa, Kinshasa, République Démocratique de Congo
| | - Jean-Jacques Muyembe
- Institut National de Recherche Biomédicale, B.P 1197 KIN 1, Kinshasa, République Démocratique de Congo
| | - Paul Mansiangi
- Faculté de Médecine, Ecole de Santé Publique, Département de Santé Environnementale, B.P 834 KIN XI, Université de Kinshasa, Kinshasa, République Démocratique de Congo
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22
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Deutsch-Feldman M, Brazeau NF, Parr JB, Thwai KL, Muwonga J, Kashamuka M, Tshefu Kitoto A, Aydemir O, Bailey JA, Edwards JK, Verity R, Emch M, Gower EW, Juliano JJ, Meshnick SR. Spatial and epidemiological drivers of Plasmodium falciparum malaria among adults in the Democratic Republic of the Congo. BMJ Glob Health 2021; 5:bmjgh-2020-002316. [PMID: 32601091 PMCID: PMC7326263 DOI: 10.1136/bmjgh-2020-002316] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 04/22/2020] [Accepted: 04/25/2020] [Indexed: 11/17/2022] Open
Abstract
Background Adults are frequently infected with malaria and may serve as a reservoir for further transmission, yet we know relatively little about risk factors for adult infections. In this study, we assessed malaria risk factors among adults using samples from the nationally representative, cross-sectional 2013–2014 Demographic and Health Survey (DHS) conducted in the Democratic Republic of the Congo (DRC). We further explored differences in risk factors by urbanicity. Methods Plasmodium falciparum infection was determined by PCR. Covariates were drawn from the DHS to model individual, community and environmental-level risk factors for infection. Additionally, we used deep sequencing data to estimate the community-level proportions of drug-resistant infections and included these estimates as potential risk factors. All identified factors were assessed for differences in associations by urbanicity. Results A total of 16 126 adults were included. Overall prevalence of malaria was 30.3% (SE=1.1) by PCR; province-level prevalence ranged from 6.7% to 58.3%. Only 17% of individuals lived in households with at least one bed-net for every two people, as recommended by the WHO. Protective factors included increasing within-household bed-net coverage (Prevalence Ratio=0.85, 95% CI=0.76–0.95) and modern housing (PR=0.58, 95% CI=0.49–0.69). Community-level protective factors included increased median wealth (PR=0.87, 95% CI=0.83–0.92). Education, wealth, and modern housing showed protective associations in cities but not in rural areas. Conclusions The DRC continues to suffer from a high burden of malaria; interventions that target high-risk groups and sustained investment in malaria control are sorely needed. Areas of high prevalence should be prioritised for interventions to target the largest reservoirs for further transmission.
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Affiliation(s)
- Molly Deutsch-Feldman
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Nicholas F Brazeau
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jonathan B Parr
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Kyaw L Thwai
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jeremie Muwonga
- National AIDS Control Program, Kinshasa, Congo (the Democratic Republic)
| | - Melchior Kashamuka
- School of Public Health, University of Kinshasa Faculty of Medicine, Kinshasa, Congo (the Democratic Republic)
| | - Antoinette Tshefu Kitoto
- School of Public Health, University of Kinshasa Faculty of Medicine, Kinshasa, Congo (the Democratic Republic)
| | - Ozkan Aydemir
- Department of Pathology and Laboratory Medicine, Brown University Warren Alpert Medical School, Providence, Rhode Island, USA
| | - Jeffrey A Bailey
- Department of Pathology and Laboratory Medicine, Brown University Warren Alpert Medical School, Providence, Rhode Island, USA
| | - Jessie K Edwards
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Robert Verity
- Medical Research Council Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Michael Emch
- Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Emily W Gower
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jonathan J Juliano
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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23
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Karemere J, Nana IG, Andrada A, Kakesa O, Mukomena Sompwe E, Likwela Losimba J, Emina J, Sadou A, Humes M, Yé Y. Associating the scale-up of insecticide-treated nets and use with the decline in all-cause child mortality in the Democratic Republic of Congo from 2005 to 2014. Malar J 2021; 20:241. [PMID: 34051817 PMCID: PMC8164747 DOI: 10.1186/s12936-021-03771-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 05/13/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To reduce the malaria burden and improve the socioeconomic status of its citizens, the Democratic Republic of Congo scaled up key malaria control interventions, especially insecticide-treated nets (ITNs), between 2005 and 2014. Since then, the effects of these interventions on malaria mortality and morbidity have not been assessed. This study aimed to measure the impact of the National Malaria Control Programme's efforts and to inform future control strategies. METHODS The authors used data from the Demographic and Health Surveys 2007 and 2013-2014 to assess trends in all-cause childhood mortality (ACCM) against trends in coverage of malaria interventions at national and subnational levels. The authors used the plausibility argument to assess the impact of the malaria control interventions and used Kaplan-Meier survival probability and Cox proportional hazard models to examine the effect of ITN ownership on child survival. Contextual factor trends affecting child survival were also considered. RESULTS Countrywide, household ownership of at least one ITN increased, from 9% in 2007 to 70% in 2013-2014. All provinces experienced similar increases, with some greater than the national level. ITN use increased between 2007 and 2013-2014 among children under five (6% to 55%). Severe anaemia (haemoglobin concentration < 8 g/dl) prevalence among children aged 6-59 months significantly decreased, from 11% (95% confidence interval [CI] 9-13%) in 2007 to 6% (95% CI 5-7%) in 2013-2014. During the same period, ACCM declined, from 148 (95% CI 132-163) to 104 (95% CI 97-112) deaths per 1000 live births. The decline in ACCM was greater among children aged 6-23 months (relative reduction of 36%), compared to children aged 24-59 months (relative reduction of 12%). Cox regression indicated that household ownership of at least one ITN reduced the risk of mortality by 24% among children under five (risk ratio = 0.76, 95% CI 0.64-0.90). Contextual factor analysis revealed marginal improvements in socioeconomic indicators and other health interventions. CONCLUSIONS Given the patterns of the coverage of malaria control interventions, patterns in ACCM by province, and marginal improvements in contextual factors, the authors conclude that the malaria control interventions have plausibly contributed to the decrease in ACCM in the Democratic Republic of Congo from 2005 to 2014.
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Affiliation(s)
- Johanna Karemere
- PMI Measure Malaria, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- ICF, Rockville, MD, USA.
| | - Ismael G Nana
- PMI Measure Malaria, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- ICF, Rockville, MD, USA
| | - Andrew Andrada
- PMI Measure Malaria, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- ICF, Rockville, MD, USA
| | - Olivier Kakesa
- PMI Measure Malaria, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- ICF, Rockville, MD, USA
| | - Eric Mukomena Sompwe
- National Malaria Control Programme, Ministry of Health, Kinshasa, Democratic Republic of Congo
- University of Lubumbashi, Lubumbashi, Democratic Republic of Congo
| | - Joris Likwela Losimba
- National Malaria Control Programme, Ministry of Health, Kinshasa, Democratic Republic of Congo
- University of Kisangani, Kisangani, Democratic Republic of Congo
| | - Jacques Emina
- University of Kinshasa, Kinshasa, Democratic Republic of Congo
- Population and Health Research Institute, Kinshasa, Democratic Republic of Congo
| | - Aboubacar Sadou
- President's Malaria Initiative/U.S. Agency for International Development, Washington, DC, USA
| | - Michael Humes
- President's Malaria Initiative/U.S. Agency for International Development, Washington, DC, USA
| | - Yazoumé Yé
- PMI Measure Malaria, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- ICF, Rockville, MD, USA
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Profiling malaria infection among under-five children in the Democratic Republic of Congo. PLoS One 2021; 16:e0250550. [PMID: 33956848 PMCID: PMC8101767 DOI: 10.1371/journal.pone.0250550] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 04/12/2021] [Indexed: 11/19/2022] Open
Abstract
Introduction In 2018, Malaria accounted for 38% of the overall morbidity and 36% of the overall mortality in the Democratic Republic of Congo (DRC). This study aimed to identify malaria socioeconomic predictors among children aged 6–59 months in DRC and to describe a socioeconomic profile of the most-at-risk children aged 6–59 months for malaria infection. Materials and methods This study used data from the 2013 DRC Demographic and Health Survey. The sample included 8,547 children aged 6–59 months who were tested for malaria by microscopy. Malaria infection status, the dependent variable, is a dummy variable characterized as a positive or negative test. The independent variables were child’s sex, age, and living arrangement; mother’s education; household’s socioeconomic variables; province of residence; and type of place of residence. Statistical analyses used the chi-square automatic interaction detector (CHAID) model and logistic regression. Results Of the 8,547 children included in the sample, 25% had malaria infection. Four variables—child’s age, mother’s education, province, and wealth index—were statistically associated with the prevalence of malaria infection in bivariate analysis and multivariate analysis (CHAID and logistic regression). The prevalence of malaria infection increases with child’s age and decreases significantly with mother’s education and the household wealth index. These findings suggest that the prevalence of malaria infection is driven by interactions among environmental factors, socioeconomic characteristics, and probably differences in the implementation of malaria programs across the country. The effect of mother’s education on malaria infection was only significant among under-five children living in Ituri, Kasaï-Central, Haut-Uele, Lomami, Nord-Ubangi, and Maniema provinces, and the effect of wealth index was significant in Mai-Ndombe, Tshopo, and Haut-Katanga provinces. Conclusion Findings from this study could be used for targeting malaria interventions in DRC. Although malaria infection is common across the country, the prevalence of children at high risk for malaria infection varies by province and other background characteristics, including age, mother’s education, wealth index, and place of residence. In light of these findings, designing provincial and multisectoral interventions could be an effective strategy to achieve zero malaria infection in DRC.
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A Scoping Review of Selected Studies on Predictor Variables Associated with the Malaria Status among Children under Five Years in Sub-Saharan Africa. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18042119. [PMID: 33671594 PMCID: PMC7927088 DOI: 10.3390/ijerph18042119] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/15/2021] [Accepted: 02/18/2021] [Indexed: 11/21/2022]
Abstract
Background/Purpose: In recent times, Sub-Saharan Africa (SSA) had been rated by the World Health Organization (WHO) as the most malaria-endemic region in the world. Evidence synthesis of the factors associated with malaria among children aged under-five in SSA is urgently needed. This would help to inform decisions that policymakers and executors in the region need to make for the effective distribution of scarce palliative resources to curb the spread of the illness. This scoping review is aimed at identifying studies that have used multivariate classical regression analysis to determine the predictors associated with malaria among children under five years old in SSA. Methods/Design: The search terms followed population, intervention, comparator, outcome, timing, setting (PICOTS), and were used in searching through the following databases: PubMed, MEDLINE, Web of Science, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Scopus, and Measure DHS. The databases were searched for published articles from January 1990 to December 2020. Results: Among the 1154 studies identified, only thirteen (13) studies met the study’s inclusion criteria. Narrative syntheses were performed on the selected papers to synchronize the various predictors identified. Factors ranging from child-related (age, birth order and use of a bed net), parental/household-related (maternal age and education status, household wealth index) and community-related variables (community wealth status, free bed net distribution) were some of the identified significant predictors. Conclusions: It is timely to have a synthesis of predictors that influence the malaria status of children under-five in SSA. The outcome of the review will increase the knowledge of the epidemiology of morbidity that will form the basis for designing efficient and cost-effective distribution of palliatives and control of malaria in SSA.
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Reyes RA, Fornace KM, Macalinao MLM, Boncayao BL, De La Fuente ES, Sabanal HM, Bareng APN, Medado IAP, Mercado ES, Baquilod MS, Luchavez JS, Hafalla JCR, Drakeley CJ, Espino FEJ. Enhanced Health Facility Surveys to Support Malaria Control and Elimination across Different Transmission Settings in the Philippines. Am J Trop Med Hyg 2021; 104:968-978. [PMID: 33534761 PMCID: PMC7941801 DOI: 10.4269/ajtmh.20-0814] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/15/2020] [Indexed: 12/12/2022] Open
Abstract
Following substantial progress in malaria control in the Philippines, new surveillance approaches are needed to identify and target residual malaria transmission. This study evaluated an enhanced surveillance approach using rolling cross-sectional surveys of all health facility attendees augmented with molecular diagnostics and geolocation. Facility surveys were carried out in three sites representing different transmission intensities: Morong, Bataan (pre-elimination), Abra de Ilog, Occidental Mindoro (stable medium risk), and Rizal, Palawan (high risk, control). Only one rapid diagnostic test (RDT)–positive infection and no PCR confirmed infections were found in Bataan and Occidental Mindoro, suggesting the absence of transmission. In Palawan, the inclusion of all health facility attendees, regardless of symptoms, and use of molecular diagnostics identified 313 infected individuals in addition to 300 cases identified by routine screening of febrile patients with the RDT or microscopy. Of these, the majority (313/613) were subpatent infections and only detected using molecular methods. Simultaneous collection of GPS coordinates on tablet-based applications allowed real-time mapping of malaria infections. Risk factor analysis showed higher risks in children and indigenous groups, with bed net use having a protective effect. Subpatent infections were more common in men and older age-groups. Overall, malaria risks were not associated with participants’ classification, and some of the non-patient clinic attendees reported febrile illnesses (1.9%, 26/1,369), despite not seeking treatment, highlighting the widespread distribution of infection in communities. Together, these data illustrate the utility of health facility–based surveys to augment surveillance data to increase the probability of detecting infections in the wider community.
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Affiliation(s)
- Ralph A Reyes
- 1Department of Parasitology, Research Institute for Tropical Medicine, Muntinlupa, Philippines
| | - Kimberly M Fornace
- 2Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Beaulah L Boncayao
- 1Department of Parasitology, Research Institute for Tropical Medicine, Muntinlupa, Philippines
| | - Ellaine S De La Fuente
- 1Department of Parasitology, Research Institute for Tropical Medicine, Muntinlupa, Philippines
| | - Hennessey M Sabanal
- 1Department of Parasitology, Research Institute for Tropical Medicine, Muntinlupa, Philippines
| | - Alison Paolo N Bareng
- 1Department of Parasitology, Research Institute for Tropical Medicine, Muntinlupa, Philippines
| | - Inez Andrea P Medado
- 3Molecular Biology Laboratory, Research Institute for Tropical Medicine, Muntinlupa, Philippines
| | - Edelwisa S Mercado
- 3Molecular Biology Laboratory, Research Institute for Tropical Medicine, Muntinlupa, Philippines
| | - Mario S Baquilod
- 4Department of Health, MIMAROPA Center for Health Development, Quirino Memorial Medical Center Compound, Quezon, Philippines
| | - Jennifer S Luchavez
- 1Department of Parasitology, Research Institute for Tropical Medicine, Muntinlupa, Philippines
| | - Julius Clemence R Hafalla
- 2Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Chris J Drakeley
- 2Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Fe Esperanza J Espino
- 1Department of Parasitology, Research Institute for Tropical Medicine, Muntinlupa, Philippines
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27
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Debebe Y, Hill SR, Tekie H, Dugassa S, Hopkins RJ, Ignell R. Malaria hotspots explained from the perspective of ecological theory underlying insect foraging. Sci Rep 2020; 10:21449. [PMID: 33293574 PMCID: PMC7722757 DOI: 10.1038/s41598-020-78021-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 11/19/2020] [Indexed: 01/16/2023] Open
Abstract
Hotspots constitute the major reservoir for residual malaria transmission, with higher malaria incidence than neighbouring areas, and therefore, have the potential to form the cornerstone for successful intervention strategies. Detection of malaria hotspots is hampered by their heterogenous spatial distribution, and the laborious nature and low sensitivity of the current methods used to assess transmission intensity. We adopt ecological theory underlying foraging in herbivorous insects to vector mosquito host seeking and modelling of fine-scale landscape features at the village level. The overall effect of environmental variables on the density of indoor mosquitoes, sporozoite infected mosquitoes, and malaria incidence, was determined using generalized linear models. Spatial analyses were used to identify hotspots for malaria incidence, as well as malaria vector density and associated sporozoite prevalence. We identify household occupancy and location as the main predictors of vector density, entomological inoculation rate and malaria incidence. We propose that the use of conventional vector control and malaria interventions, integrated with their intensified application targeting predicted hotspots, can be used to reduce malaria incidence in endemic and residual malaria settings.
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Affiliation(s)
- Yared Debebe
- Department of Zoological Sciences, Addis Ababa University, PO. Box 1176, Addis Ababa, Ethiopia
| | - Sharon Rose Hill
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Habte Tekie
- Department of Zoological Sciences, Addis Ababa University, PO. Box 1176, Addis Ababa, Ethiopia
| | - Sisay Dugassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, PO. Box 1176, Addis Ababa, Ethiopia
| | | | - Rickard Ignell
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
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28
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Topazian HM, Gumbo A, Puerto-Meredith S, Njiko R, Mwanza A, Kayange M, Mwalilino D, Mvula B, Tegha G, Mvalo T, Edwards JK, Emch M, Pettifor A, Smith JS, Hoffman I, Meshnick SR, Juliano JJ. Asymptomatic Plasmodium falciparum malaria prevalence among adolescents and adults in Malawi, 2015-2016. Sci Rep 2020; 10:18740. [PMID: 33127922 PMCID: PMC7603306 DOI: 10.1038/s41598-020-75261-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/13/2020] [Indexed: 11/25/2022] Open
Abstract
Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016. While children report the highest rates of clinical disease, adults are thought to be an important reservoir to sustained transmission due to persistent asymptomatic infection. The 2015–2016 Malawi Demographic and Health Survey was a nationally representative household survey which collected dried blood spots from 15,125 asymptomatic individuals ages 15–54 between October 2015 and February 2016. We performed quantitative polymerase chain reaction on 7,393 samples, detecting an overall P. falciparum prevalence of 31.1% (SE = 1.1). Most infections (55.6%) had parasitemias ≤ 10 parasites/µL. While 66.2% of individuals lived in a household that owned a bed net, only 36.6% reported sleeping under a long-lasting insecticide-treated net (LLIN) the previous night. Protective factors included urbanicity, greater wealth, higher education, and lower environmental temperatures. Living in a household with a bed net (prevalence difference 0.02, 95% CI − 0.02 to 0.05) and sleeping under an LLIN (0.01; − 0.02 to 0.04) were not protective against infection. Our findings demonstrate a higher parasite prevalence in adults than published estimates among children. Understanding the prevalence and distribution of asymptomatic infection is essential for targeted interventions.
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Affiliation(s)
- Hillary M Topazian
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA.
| | - Austin Gumbo
- National Malaria Control Programme, Malawi Ministry of Health, Lilongwe, Malawi
| | | | - Ruth Njiko
- University of North Carolina Project-Malawi, Lilongwe, Malawi
| | - Alexis Mwanza
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA
| | - Michael Kayange
- National Malaria Control Programme, Malawi Ministry of Health, Lilongwe, Malawi
| | - David Mwalilino
- National HIV Reference Laboratory, Malawi Ministry of Health, Lilongwe, Malawi
| | - Bernard Mvula
- National HIV Reference Laboratory, Malawi Ministry of Health, Lilongwe, Malawi
| | - Gerald Tegha
- University of North Carolina Project-Malawi, Lilongwe, Malawi
| | - Tisungane Mvalo
- University of North Carolina Project-Malawi, Lilongwe, Malawi.,Department of Pediatrics, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Jessie K Edwards
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA
| | - Michael Emch
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA.,Department of Geography, University of North Carolina, Chapel Hill, NC, USA
| | - Audrey Pettifor
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA.,Carolina Population Center, University of North Carolina, Chapel Hill, NC, USA
| | - Jennifer S Smith
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA
| | - Irving Hoffman
- University of North Carolina Project-Malawi, Lilongwe, Malawi.,Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, NC, USA
| | - Steven R Meshnick
- Department of Epidemiology, University of North Carolina, Chapel Hill, NC, 27510, USA
| | - Jonathan J Juliano
- Division of Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
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29
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Tamari N, Minakawa N, Sonye GO, Awuor B, Kongere JO, Hashimoto M, Kataoka M, Munga S. Protective effects of Olyset® Net on Plasmodium falciparum infection after three years of distribution in western Kenya. Malar J 2020; 19:373. [PMID: 33076928 PMCID: PMC7574443 DOI: 10.1186/s12936-020-03444-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 10/10/2020] [Indexed: 12/23/2022] Open
Abstract
Background Several types of insecticides, treating technologies and materials are available for long-lasting insecticide-treated nets (LLINs). The variations may result in different efficacies against mosquitoes and correspondingly infection risks for the Plasmodium falciparum malaria parasite. This cross-sectional study investigated whether infection risk varied among children who slept under different LLIN brands in rural villages of western Kenya. Methods Children sleeping under various types of LLINs were tested for P. falciparum infection using a diagnostic polymerase chain reaction (PCR) assay. Data were collected for other potential factors associated with infection risk: sleeping location (with bed/without bed), number of persons sharing the same net, dwelling wall material, gap of eaves (open/close), proportional hole index, socio-economic status, and density of indoor resting anophelines. Bed-net efficacy against the Anopheles gambiae susceptible strain was estimated using the WHO cone test and the tunnel test. The residual insecticide content on nets was measured. Results Seven LLIN brands were identified, and deltamethrin-based DawaPlus® 2.0 was the most popular (48%) followed by permethrin-based Olyset® Net (28%). The former LLIN was distributed in the area about six months before the present study was conducted, and the latter net was distributed at least three years before. Of 254 children analysed, P. falciparum PCR-positive prevalence was 58% for DawaPlus® 2.0 users and 38% for Olyset® users. The multiple regression analysis revealed that the difference was statistically significant (adjusted OR: 0.67, 95% credible interval: 0.45–0.97), whereas the confounders were not statistically important. Among randomly selected net samples, all DawaPlus® 2.0 (n = 20) and 95% of Olyset® (n = 19) passed either the cone test or the tunnel test. Conclusions Olyset® was more effective in reducing infection risk compared with DawaPlus® 2.0. Although the data from the present study were too limited to explain the mechanism clearly, the results suggest that the characteristics of the former brand are more suitable for the conditions, such as vector species composition, of the study area.
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Affiliation(s)
- Noriko Tamari
- Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Nagasaki, 852-8523, Japan. .,College of Public Health, The University of Arizona, 1295 N Martin Ave, Tucson, AZ, 85724, USA.
| | - Noboru Minakawa
- Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Nagasaki, 852-8523, Japan
| | - George O Sonye
- Ability To Solve By Knowledge Project, Mbita, Homa Bay, Kenya
| | - Beatrice Awuor
- Ability To Solve By Knowledge Project, Mbita, Homa Bay, Kenya
| | - James O Kongere
- Centre for Research in Tropical Medicine and Community Development, Nairobi, Kenya
| | - Muneaki Hashimoto
- National Institute of Advanced Industrial Science and Technology (AIST), Health Research Institute, Kagawa, Japan
| | - Masatoshi Kataoka
- National Institute of Advanced Industrial Science and Technology (AIST), Health Research Institute, Kagawa, Japan
| | - Stephen Munga
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
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30
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Mosha JF, Lukole E, Charlwood JD, Wright A, Rowland M, Bullock O, Manjurano A, Kisinza W, Mosha FW, Kleinschmidt I, Protopopoff N. Risk factors for malaria infection prevalence and household vector density between mass distribution campaigns of long-lasting insecticidal nets in North-western Tanzania. Malar J 2020; 19:297. [PMID: 32819368 PMCID: PMC7441624 DOI: 10.1186/s12936-020-03369-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 08/10/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) are the most widely deployed vector control intervention in sub-Saharan Africa to prevent malaria. Recent reports indicate selection of pyrethroid insecticide resistance is widespread in mosquito vectors. This paper explores risk factors associated with malaria infection prevalence and vector density between mass distribution campaigns, changes in net coverage, and loss of protection in an area of high pyrethroid resistance in Northwest Tanzania. METHODS A cross sectional malaria survey of 3456 children was undertaken in 2014 in Muleba district, Kagera region west of Lake Victoria. Vector density was assessed using indoor light traps and outdoor tent traps. Anophelines were identified to species using PCR and tested for Plasmodium falciparum circumsporozoite protein. Logistic regression was used to identify household and environmental factors associated with malaria infection and regression binomial negative for vector density. RESULTS LLIN use was 27.7%. Only 16.9% of households had sufficient nets to cover all sleeping places. Malaria infection was independently associated with access to LLINs (OR: 0.57; 95% CI 0.34-0.98). LLINs less than 2 years old were slightly more protective than older LLINs (53 vs 65% prevalence of infection); however, there was no evidence that LLINs in good condition (hole index < 65) were more protective than LLINs, which were more holed. Other risk factors for malaria infection were age, group, altitude and house construction quality. Independent risk factors for vector density were consistent with malaria outcomes and included altitude, wind, livestock, house quality, open eaves and LLIN usage. Indoor collections comprised 4.6% Anopheles funestus and 95.4% Anopheles gambiae of which 4.5% were Anopheles arabiensis and 93.5% were Anopheles gambiae sensu stricto. CONCLUSION Three years after the mass distribution campaign and despite top-ups, LLIN usage had declined considerably. While children living in households with access to LLINs were at lower risk of malaria, infection prevalence remained high even among users of LLINs in good condition. While effort should be made to maintain high coverage between campaigns, distribution of standard pyrethroid-only LLINs appears insufficient to prevent malaria transmission in this area of intense pyrethroid resistance.
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Affiliation(s)
- Jacklin F Mosha
- National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania.
| | - Eliud Lukole
- National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - J Derek Charlwood
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Alexandra Wright
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Mark Rowland
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Olivia Bullock
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Alphaxard Manjurano
- National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - William Kisinza
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania
| | - Franklin W Mosha
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Immo Kleinschmidt
- MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Natacha Protopopoff
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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31
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Mitchell CL, Brazeau NF, Keeler C, Mwandagalirwa MK, Tshefu AK, Juliano JJ, Meshnick SR. Under the Radar: Epidemiology of Plasmodium ovale in the Democratic Republic of the Congo. J Infect Dis 2020; 223:1005-1014. [PMID: 32766832 DOI: 10.1093/infdis/jiaa478] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 07/28/2020] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Plasmodium ovale is an understudied malaria species prevalent throughout much of sub-Saharan Africa. Little is known about the distribution of ovale malaria and risk factors for infection in areas of high malaria endemicity. METHODS Using the 2013 Democratic Republic of the Congo (DRC) Demographic and Health Survey, we conducted a risk factor analysis for P. ovale infections. We evaluated geographic clustering of infections and speciated to P. ovale curtisi and P. ovale wallikeri through deep sequencing. RESULTS Of 18 149 adults tested, we detected 143 prevalent P. ovale infections (prevalence estimate 0.8%; 95% confidence interval [CI], .59%-.98%). Prevalence ratios (PR) for significant risk factors were: male sex PR = 2.12 (95% CI, 1.38-3.26), coprevalent P. falciparum PR = 3.52 (95% CI, 2.06-5.99), and rural residence PR = 2.19 (95% CI, 1.31-3.66). P. ovale was broadly distributed throughout the DRC; an elevated cluster of infections was detected in the south-central region. Speciation revealed P. ovale curtisi and P. ovale wallikeri circulating throughout the country. CONCLUSIONS P. ovale persists broadly in the DRC, a high malaria burden country. For successful elimination of all malaria species, P. ovale needs to be on the radar of malaria control programs.
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Affiliation(s)
- Cedar L Mitchell
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Nicholas F Brazeau
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Corinna Keeler
- Department of Geography, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Melchior Kashamuka Mwandagalirwa
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA.,Kinshasa School of Public Health, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Antoinette K Tshefu
- Kinshasa School of Public Health, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Jonathan J Juliano
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA.,Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA.,Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
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Ngufor C, Agbevo A, Fagbohoun J, Fongnikin A, Rowland M. Efficacy of Royal Guard, a new alpha-cypermethrin and pyriproxyfen treated mosquito net, against pyrethroid-resistant malaria vectors. Sci Rep 2020; 10:12227. [PMID: 32699237 PMCID: PMC7376134 DOI: 10.1038/s41598-020-69109-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 07/06/2020] [Indexed: 11/10/2022] Open
Abstract
Royal Guard is a new insecticide-treated bed-net incorporated with a mixture of alpha-cypermethrin and pyriproxyfen (an insect growth regulator). We assessed its efficacy and wash-resistance in laboratory and experimental hut studies following WHO guidelines. Mosquitoes that survived exposure to the net were kept in separate oviposition chambers and observed for the reproductive effects of pyriproxyfen. In laboratory assays, Royal Guard induced > 80% mortality and > 90% blood-feeding inhibition of An. gambiae sl mosquitoes before and after 20 standardised washes and sterilised blood-fed mosquitoes which remained alive after exposure to the net. In an experimental hut trial against wild free-flying pyrethroid-resistant An. gambiae sl in Cové Benin, Royal Guard through the pyrethroid component induced comparable levels of mortality and blood-feeding inhibition to a standard pyrethroid-only treated net before and after 20 washes and sterilised large proportions of surviving blood-fed female mosquitoes through the pyriproxyfen component; Royal Guard induced 83% reduction in oviposition and 95% reduction in offspring before washing and 25% reduction in oviposition and 50% reduction in offspring after 20 washes. Royal Guard has the potential to improve malaria vector control and provide better community protection against clinical malaria in pyrethroid-resistant areas compared to standard pyrethroid-only LLINs.
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Affiliation(s)
- Corine Ngufor
- London School of Hygiene and Tropical Medicine (LSHTM), London, UK. .,Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin. .,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
| | - Abel Agbevo
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin.,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Josias Fagbohoun
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin.,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Augustin Fongnikin
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin.,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Mark Rowland
- London School of Hygiene and Tropical Medicine (LSHTM), London, UK.,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
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Odufuwa OG, Ross A, Mlacha YP, Juma O, Mmbaga S, Msellemu D, Moore S. Household factors associated with access to insecticide-treated nets and house modification in Bagamoyo and Ulanga districts, Tanzania. Malar J 2020; 19:220. [PMID: 32576180 PMCID: PMC7313165 DOI: 10.1186/s12936-020-03303-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 06/18/2020] [Indexed: 08/29/2023] Open
Abstract
BACKGROUND Insecticide-treated nets (ITNs) and house modifications are proven vector control tools, yet in most regions, full coverage has not been achieved. This study investigates household factors associated with access to ITNs and house modification in Tanzania. METHODS Baseline cross-sectional survey data from previous studies on spatial repellants and indoor residual spray evaluation was analysed from 6757 households in Bagamoyo (60 km north of Dar es Salaam) and 1241 households in Ulanga (a remote rural area in southeast Tanzania), respectively. Regression models were used to estimate the associations between the outcomes: population access to ITNs, access to ITN per sleeping spaces, window screens and closed eaves, and the covariates household size, age, gender, pregnancy, education, house size, house modification (window screens and closed eaves) and wealth. RESULTS Population access to ITNs (households with one ITN per two people that stayed in the house the previous night of the survey) was 69% (n = 4663) and access to ITNs per sleeping spaces (households with enough ITNs to cover all sleeping spaces used the previous night of the survey) was 45% (n = 3010) in Bagamoyo, 3 years after the last mass campaign. These findings are both lower than the least 80% coverage target of the Tanzania National Malaria Strategic Plan (Tanzania NMSP). In Ulanga, population access to ITNs was 92% (n = 1143) and ITNs per sleeping spaces was 88% (n = 1093), 1 year after the last Universal Coverage Campaign (UCC). Increased household size was significantly associated with lower access to ITNs even shortly after UCC. House modification was common in both areas but influenced by wealth. In Bagamoyo, screened windows were more common than closed eaves (65% vs 13%), whereas in Ulanga more houses had closed eaves than window screens (55% vs 12%). CONCLUSION Population access to ITNs was substantially lower than the targets of the Tanzania NMSP after 3 years and lower among larger households after 1 year following ITN campaign. House modification was common in both areas, associated with wealth. Improved access to ITNs and window screens through subsidies and Behaviour Change Communication (BCC) strategies, especially among large and poor households and those headed by people with a low level of education, could maximize the uptake of a combination of these two interventions.
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Affiliation(s)
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Yeromin P Mlacha
- Ifakara Health Institute, Bagamoyo, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Omary Juma
- Ifakara Health Institute, Bagamoyo, Tanzania
| | | | - Daniel Msellemu
- Ifakara Health Institute, Bagamoyo, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Sarah Moore
- Ifakara Health Institute, Bagamoyo, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
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34
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Mansiangi P, Umesumbu S, Etewa I, Zandibeni J, Bafwa N, Blaufuss S, Olapeju B, Ntoya F, Sadou A, Irish S, Mukomena E, Kalindula L, Watsenga F, Akogbeto M, Babalola S, Koenker H, Kilian A. Comparing the durability of the long-lasting insecticidal nets DawaPlus ® 2.0 and DuraNet© in northwest Democratic Republic of Congo. Malar J 2020; 19:189. [PMID: 32448213 PMCID: PMC7247235 DOI: 10.1186/s12936-020-03262-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 05/15/2020] [Indexed: 11/30/2022] Open
Abstract
Background Anecdotal reports from DRC suggest that long-lasting insecticidal nets (LLIN) distributed through mass campaigns in DRC may not last the expected average three years. To provide the National Malaria Control Programme with evidence on physical and insecticidal durability of nets distributed during the 2016 mass campaign, two brands of LLIN, DawaPlus® 2.0 and DuraNet©, were monitored in neighbouring and similar health zones in Sud Ubangi and Mongala Provinces. Methods This was a prospective cohort study of representative samples of households from two health zones recruited at baseline, 2 months after the mass campaign. All campaign nets in these households were labelled, and followed up over a period of 31 months. Primary outcome was the “proportion of nets surviving in serviceable condition” based on attrition and integrity measures and the median survival in years. The outcome for insecticidal durability was determined by bio-assay from subsamples of campaign nets. Results A total of 754 campaign nets (109% of target) from 240 households were included in the study. Definite outcomes could be determined for 67% of the cohort nets in Sud Ubangi and 74% in Mongala. After 31 months all-cause attrition was 57% in Sud Ubangi and 76% in Mongala (p = 0.005) and attrition due to wear and tear was 26% in Sud Ubangi and 48% in Mongala (p = 0.0009). Survival in serviceable condition at the last survey was 37% in Sud Ubangi and 17% in Mongala (p = 0.003). Estimated median survival was 1.6 years for the DawaPlus® 2.0 in Mongala (95% CI 1.3–1.9) and 2.2 years for the DuraNet in Sud Ubangi (95% CI 2.0–2.4). Multivariable Cox proportionate hazard models suggest that the difference between sites was mainly attributable to the LLIN brand. Insecticidal effectiveness was optimal for DuraNet©, but significantly dropped after 24 months for DawaPlus® 2.0. Conclusions In the environment of northwest DRC the polyethylene LLIN DuraNet© performed significantly better than the polyester LLIN DawaPlus® 2.0, but both were below a three-year median survival. Improvement of net care behaviours should be able to improve physical durability.
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Affiliation(s)
- Paul Mansiangi
- Ecole de Santé Publique, Université de Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Solange Umesumbu
- National Malaria Control Programme, Kinshasa, Democratic Republic of Congo
| | - Irène Etewa
- Ecole de Santé Publique, Université de Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Jacques Zandibeni
- Ecole de Santé Publique, Université de Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Nissi Bafwa
- Ecole de Santé Publique, Université de Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Sean Blaufuss
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Bolanle Olapeju
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Ferdinand Ntoya
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Kinshasa, Democratic Republic of Congo
| | - Aboubacar Sadou
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Kinshasa, Democratic Republic of Congo
| | - Seth Irish
- U.S. President's Malaria Initiative, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Eric Mukomena
- National Malaria Control Programme, Kinshasa, Democratic Republic of Congo
| | - Lydie Kalindula
- National Malaria Control Programme, Kinshasa, Democratic Republic of Congo
| | - Francis Watsenga
- Institut Nationale de Recherche Bio-Medicale, Kinshasa, Democratic Republic of Congo
| | - Martin Akogbeto
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Stella Babalola
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Hannah Koenker
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Albert Kilian
- PMI VectorWorks Project, Tropical Health LLP, Montagut, Spain.
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Enahoro I, Eikenberry S, Gumel AB, Huijben S, Paaijmans K. Long-lasting insecticidal nets and the quest for malaria eradication: a mathematical modeling approach. J Math Biol 2020; 81:113-158. [PMID: 32447420 DOI: 10.1007/s00285-020-01503-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 03/18/2020] [Indexed: 10/24/2022]
Abstract
Recent dramatic declines in global malaria burden and mortality can be largely attributed to the large-scale deployment of insecticidal-based measures, namely long-lasting insecticidal nets (LLINs) and indoor residual spraying. However, the sustainability of these gains, and the feasibility of global malaria eradication by 2040, may be affected by increasing insecticide resistance among the Anopheles malaria vector. We employ a new differential-equations based mathematical model, which incorporates the full, weather-dependent mosquito lifecycle, to assess the population-level impact of the large-scale use of LLINs, under different levels of Anopheles pyrethroid insecticide resistance, on malaria transmission dynamics and control in a community. Moreover, we describe the bednet-mosquito interaction using parameters that can be estimated from the large experimental hut trial literature under varying levels of effective pyrethroid resistance. An expression for the basic reproduction number, [Formula: see text], as a function of population-level bednet coverage, is derived. It is shown, owing to the phenomenon of backward bifurcation, that [Formula: see text] must be pushed appreciably below 1 to eliminate malaria in endemic areas, potentially complicating eradication efforts. Numerical simulations of the model suggest that, when the baseline [Formula: see text] is high (corresponding roughly to holoendemic malaria), very high bednet coverage with highly effective nets is necessary to approach conditions for malaria elimination. Further, while >50% bednet coverage is likely sufficient to strongly control or eliminate malaria from areas with a mesoendemic malaria baseline, pyrethroid resistance could undermine control and elimination efforts even in this setting. Our simulations show that pyrethroid resistance in mosquitoes appreciably reduces bednet effectiveness across parameter space. This modeling study also suggests that increasing pre-bloodmeal deterrence of mosquitoes (deterring them from entry into protected homes) actually hampers elimination efforts, as it may focus mosquito biting onto a smaller unprotected host subpopulation. Finally, we observe that temperature affects malaria potential independently of bednet coverage and pyrethroid-resistance levels, with both climate change and pyrethroid resistance posing future threats to malaria control.
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Affiliation(s)
- Iboi Enahoro
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, USA
| | - Steffen Eikenberry
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, USA
| | - Abba B Gumel
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, USA. .,Department of Mathematics and Applied Mathematics, University of Pretoria, Pretoria, 0002, South Africa.
| | - Silvie Huijben
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, USA
| | - Krijn Paaijmans
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, USA.,The Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Tempe, AZ, USA
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Wat'senga F, Agossa F, Manzambi EZ, Illombe G, Mapangulu T, Muyembe T, Clark T, Niang M, Ntoya F, Sadou A, Plucinski M, Li Y, Messenger LA, Fornadel C, Oxborough RM, Irish SR. Intensity of pyrethroid resistance in Anopheles gambiae before and after a mass distribution of insecticide-treated nets in Kinshasa and in 11 provinces of the Democratic Republic of Congo. Malar J 2020; 19:169. [PMID: 32354333 PMCID: PMC7193383 DOI: 10.1186/s12936-020-03240-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/16/2020] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Between 2011 and 2018, an estimated 134.8 million pyrethroid-treated long-lasting insecticidal nets (LLINs) were distributed nationwide in the Democratic Republic of Congo (DRC) for malaria control. Pyrethroid resistance has developed in DRC in recent years, but the intensity of resistance and impact on LLIN efficacy was not known. Therefore, the intensity of resistance of Anopheles gambiae sensu lato (s.l.) to permethrin and deltamethrin was monitored before and after a mass distribution of LLINs in Kinshasa in December 2016, and in 6 other sites across the country in 2017 and 11 sites in 2018. METHODS In Kinshasa, CDC bottle bioassays using 1, 2, 5, and 10 times the diagnostic dose of permethrin and deltamethrin were conducted using An. gambiae s.l. collected as larvae and reared to adults. Bioassays were conducted in four sites in Kinshasa province 6 months before a mass distribution of deltamethrin-treated LLINs and then two, six, and 10 months after the distribution. One site in neighbouring Kongo Central province was used as a control (no mass campaign of LLIN distribution during the study). Nationwide intensity assays were conducted in six sites in 2017 using CDC bottle bioassays and in 11 sites in 2018 using WHO intensity assays. A sub-sample of An. gambiae s.l. was tested by PCR to determine species composition and frequency of kdr-1014F and 1014S alleles. RESULTS In June 2016, before LLIN distribution, permethrin resistance intensity was high in Kinshasa; the mean mortality rate was 43% at the 5× concentration and 73% at the 10× concentration. Bioassays at 3 time points after LLIN distribution showed considerable variation by site and time and there was no consistent evidence for an increase in pyrethroid resistance intensity compared to the neighbouring control site. Tests of An. gambiae s.l. in 6 sites across the country in 2017 and 11 sites in 2018 showed all populations were resistant to the diagnostic doses of 3 pyrethroids. In 2018, the intensity of resistance varied by site, but was generally moderate for all three pyrethroids, with survivors at ×5 the diagnostic dose. Anopheles gambiae sensu stricto (s.s.) was the most common species identified across 11 sites in DRC, but in Kinshasa, An. gambiae s.s. (91%) and Anopheles coluzzii (8%) were sympatric. CONCLUSIONS Moderate or high intensity pyrethroid resistance was detected nationwide in DRC and is a serious threat to sustained malaria control with pyrethroid LLINs. Next generation nets (PBO nets or bi-treated nets) should be considered for mass distribution.
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Affiliation(s)
- Francis Wat'senga
- Institut National de Recherche Biomédicale, PO Box 1192, Kinshasa, Democratic Republic of Congo
| | - Fiacre Agossa
- USAID President's Malaria Initiative, VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Emile Z Manzambi
- Institut National de Recherche Biomédicale, PO Box 1192, Kinshasa, Democratic Republic of Congo
| | - Gillon Illombe
- Institut National de Recherche Biomédicale, PO Box 1192, Kinshasa, Democratic Republic of Congo
| | - Tania Mapangulu
- Institut National de Recherche Biomédicale, PO Box 1192, Kinshasa, Democratic Republic of Congo
| | - Tamfum Muyembe
- Institut National de Recherche Biomédicale, PO Box 1192, Kinshasa, Democratic Republic of Congo
| | - Tiffany Clark
- USAID President's Malaria Initiative, VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Mame Niang
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Kinshasa, Democratic Republic of the Congo
| | - Ferdinand Ntoya
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Kinshasa, Democratic Republic of the Congo
| | - Aboubacar Sadou
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Kinshasa, Democratic Republic of the Congo
| | - Mateusz Plucinski
- U.S. President's Malaria Initiative and Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA, 30329, USA
| | - Yikun Li
- U.S. President's Malaria Initiative and Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA, 30329, USA
| | - Louisa A Messenger
- U.S. President's Malaria Initiative and Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA, 30329, USA.,London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Christen Fornadel
- U.S. President's Malaria Initiative, United States Agency for International Development, Bureau for Global Health, Office of Infectious Disease, 2100 Crystal Drive, Arlington, VA, 22202, USA
| | - Richard M Oxborough
- USAID President's Malaria Initiative, VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Seth R Irish
- U.S. President's Malaria Initiative and Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA, 30329, USA.
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Janko M, Goel V, Emch M. Extending multilevel spatial models to include spatially varying coefficients. Health Place 2019; 60:102235. [PMID: 31778846 DOI: 10.1016/j.healthplace.2019.102235] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 10/04/2019] [Accepted: 10/08/2019] [Indexed: 11/27/2022]
Abstract
Multilevel models have long been used by health geographers working on questions of space, place, and health. Similarly, health geographers have pursued interests in determining whether or not the effect of an exposure on a health outcome varies spatially. However, relatively little work has sought to use multilevel models to explore spatial variability in the effects of a contextual exposure on a health outcome. Methodologically, extending multilevel models to allow intercepts and slopes to vary spatially is straightforward. The purpose of this paper, therefore, is to show how multilevel spatial models can be extended to include spatially varying covariate effects. We provide an empirical example on the effect of agriculture on malaria risk in children under 5 years of age in the Democratic Republic of Congo.
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Affiliation(s)
- Mark Janko
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USA; Duke Global Health Institute, Duke University, Durham, NC, USA.
| | - Varun Goel
- Department of Geography, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA; Carolina Population Center, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Michael Emch
- Department of Geography, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA; Carolina Population Center, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA; Department of Epidemiology, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
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38
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Deutsch-Feldman M, Aydemir O, Carrel M, Brazeau NF, Bhatt S, Bailey JA, Kashamuka M, Tshefu AK, Taylor SM, Juliano JJ, Meshnick SR, Verity R. The changing landscape of Plasmodium falciparum drug resistance in the Democratic Republic of Congo. BMC Infect Dis 2019; 19:872. [PMID: 31640574 PMCID: PMC6805465 DOI: 10.1186/s12879-019-4523-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/30/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Drug resistant malaria is a growing concern in the Democratic Republic of the Congo (DRC), where previous studies indicate that parasites resistant to sulfadoxine/pyrimethamine or chloroquine are spatially clustered. This study explores longitudinal changes in spatial patterns to understand how resistant malaria may be spreading within the DRC, using samples from nation-wide population-representative surveys. METHODS We selected 552 children with PCR-detectable Plasmodium falciparum infection and identified known variants in the pfdhps and pfcrt genes associated with resistance. We compared the proportion of mutant parasites in 2013 to those previously reported from adults in 2007, and identified risk factors for carrying a resistant allele using multivariate mixed-effects modeling. Finally, we fit a spatial-temporal model to the observed data, providing smooth allele frequency estimates over space and time. RESULTS The proportion of co-occurring pfdhps K540E/A581G mutations increased by 16% between 2007 and 2013. The spatial-temporal model suggests that the spatial range of the pfdhps double mutants expanded over time, while the prevalence and range of pfcrt mutations remained steady. CONCLUSIONS This study uses population-representative samples to describe the changing landscape of SP resistance within the DRC, and the persistence of chloroquine resistance. Vigilant molecular surveillance is critical for controlling the spread of resistance.
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Affiliation(s)
- Molly Deutsch-Feldman
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, USA.
| | - Ozkan Aydemir
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA
| | - Margaret Carrel
- Department of Geographical & Sustainability Sciences, University of Iowa, Iowa City, IA, USA
| | - Nicholas F Brazeau
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, USA
| | - Samir Bhatt
- Medical Research Council Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Jeffrey A Bailey
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA
| | - Melchior Kashamuka
- Ecole de Santé Publique, , Faculté de Médecine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Antoinette K Tshefu
- Ecole de Santé Publique, , Faculté de Médecine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Steve M Taylor
- Division of Infectious Diseases and Duke Global Health Institute, Duke University, Durham, NC, USA
| | - Jonathan J Juliano
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, USA.,Division of Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, USA
| | - Robert Verity
- Medical Research Council Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
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Lechthaler F, Matthys B, Lechthaler-Felber G, Likwela JL, Mavoko HM, Rika JM, Mutombo MM, Ruckstuhl L, Barczyk J, Shargie E, Prytherch H, Lengeler C. Trends in reported malaria cases and the effects of malaria control in the Democratic Republic of the Congo. PLoS One 2019; 14:e0219853. [PMID: 31344062 PMCID: PMC6658057 DOI: 10.1371/journal.pone.0219853] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 07/02/2019] [Indexed: 12/05/2022] Open
Abstract
Background Considerable upscaling of malaria control efforts have taken place over the last 15 years in the Democratic Republic of Congo, the country with the second highest malaria case load after Nigeria. Malaria control interventions have been strengthened in line with the Millenium Development Goals. We analysed the effects of these interventions on malaria cases at health facility level, using a retrospective trend analysis of malaria cases between 2005 and 2014. Data were collected from outpatient and laboratory registers based on a sample of 175 health facilities that represents all eco-epidemiological malaria settings across the country. Methods We applied a time series analysis to assess trends of suspected and confirmed malaria cases, by health province and for different age groups. A linear panel regression model controlled for non-malaria outpatient cases, rain fall, nightlight intensity, health province and time fixed effects, was used to examine the relationship between the interventions and malaria case occurrences, as well as test positivity rates. Results Overall, recorded suspected and confirmed malaria cases in the DRC have increased. The sharp increase in confirmed cases from 2010 coincides with the introduction of the new treatment policy and the resulting scale-up of diagnostic testing. Controlling for confounding factors, the introduction of rapid diagnostic tests (RDTs) was significantly associated with the number of tested and confirmed cases. The test positivity rate fluctuated around 40% without showing any trend. Conclusion The sharp increase in confirmed malaria cases from 2010 is unlikely to be due to a resurgence of malaria, but is clearly associated with improved diagnostic availability, mainly the introduction of RDTs. Before that, a great part of malaria cases were treated based on clinical suspicion. This finding points to a better detection of cases that potentially contributed to improved case management. Furthermore, the expansion of diagnostic testing along with the increase in confirmed cases implies that before 2010, cases were underreported, and that the accuracy of routine data to describe malaria incidence has improved.
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Affiliation(s)
- Filippo Lechthaler
- Swiss Centre for International Health, Swiss Tropical and Public Health Institute, Basel, Canton of Basel Stadt, Switzerland
- University of Basel, Basel, Canton of Basel Stadt, Switzerland
- School of Agricultural, Forest and Food Sciences, Bern University of Applied Sciences, Zollikofen, Canton of Bern, Switzerland
| | - Barbara Matthys
- Swiss Centre for International Health, Swiss Tropical and Public Health Institute, Basel, Canton of Basel Stadt, Switzerland
- University of Basel, Basel, Canton of Basel Stadt, Switzerland
- * E-mail:
| | - Giulia Lechthaler-Felber
- Faculty of Business and Economics, University of Basel, Basel, Canton of Basel Stadt, Switzerland
| | - Joris Losimba Likwela
- Soins de Santé en Milieu Rural (non-profit organization SANRU), Kinshasa, Democratic Republic of the Congo
| | - Hypolite Muhindo Mavoko
- Tropical Medicine Department, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Junior Matangila Rika
- Tropical Medicine Department, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Meschac Mutombo Mutombo
- National Malaria Control Program, Ministry of Health, Kinshasa, Democratic Republic of the Congo
| | - Laura Ruckstuhl
- University of Basel, Basel, Canton of Basel Stadt, Switzerland
- Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Basel, Canton of Basel Stadt, Switzerland
| | - Joanna Barczyk
- The Global Fund to fight AIDS, Tuberculosis, and Malaria, Geneva, Canton of Geneva, Switzerland
| | - Estifanos Shargie
- The Global Fund to fight AIDS, Tuberculosis, and Malaria, Geneva, Canton of Geneva, Switzerland
| | - Helen Prytherch
- Swiss Centre for International Health, Swiss Tropical and Public Health Institute, Basel, Canton of Basel Stadt, Switzerland
- University of Basel, Basel, Canton of Basel Stadt, Switzerland
| | - Christian Lengeler
- University of Basel, Basel, Canton of Basel Stadt, Switzerland
- Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Basel, Canton of Basel Stadt, Switzerland
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Onyiah AP, Ajayi IO, Dada-Adegbola HO, Adedokun BO, Balogun MS, Nguku PM, Ajumobi OO. Long-lasting insecticidal net use and asymptomatic malaria parasitaemia among household members of laboratory-confirmed malaria patients attending selected health facilities in Abuja, Nigeria, 2016: A cross-sectional survey. PLoS One 2018; 13:e0203686. [PMID: 30212496 PMCID: PMC6136754 DOI: 10.1371/journal.pone.0203686] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 08/24/2018] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION In Nigeria, malaria remains a major burden. There is the presupposition that household members could have common exposure to malaria parasite and use of long-lasting insecticidal net (LLIN) could reduce transmission. This study was conducted to identify factors associated with asymptomatic malaria parasitaemia and LLIN use among households of confirmed malaria patients in Abuja, Nigeria. METHODS A cross-sectional survey was conducted from March to August 2016 in twelve health facilities selected from three area councils in Abuja, Nigeria. Participants were selected using multi-stage sampling technique. Overall, we recruited 602 participants from 107 households linked to 107 malaria patients attending the health facilities. Data on LLIN ownership, utilization, and house characteristics were collected using a semi-structured questionnaire. Blood samples of household members were examined for malaria parasitaemia using microscopy. Data were analyzed using descriptive statistics, Chi-square, and logistic regression (α = 0.05). RESULTS Median age of respondents was 16.5 years (Interquartile range: 23 years); 55.0% were females. Proportions of households that owned and used at least one LLIN were 44.8% and 33.6%, respectively. Parasitaemia was detected in at least one family member of 102 (95.3%) index malaria patients. Prevalence of asymptomatic malaria parasitaemia among study participants was 421/602 (69.9%). No association was found between individual LLIN use and malaria parasitaemia (odds ratio: 0.9, 95% confidence interval (95%CI): 0.6-1.3) among study participants. Having bushes around the homes was associated with having malaria parasitaemia (adjusted OR (aOR): 2.7, 95%CI: 1.7-4.2) and less use of LLIN (aOR: 0.4, 95%CI: 0.2-0.9). Living in Kwali (aOR: 0.1, 95% CI: 0.0-0.2) was associated with less use of LLIN. CONCLUSION High prevalence of asymptomatic malaria and low use of LLIN among household members of malaria patients portend the risk of intra-household common source of malaria transmission. We recommend household health education on LLIN use and environmental management. Study to explore the role of preventive treatment of household members of confirmed malaria patient in curbing transmission is suggested. Strategies promoting LLIN use need to be intensified in Kwali.
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Affiliation(s)
- Amaka Pamela Onyiah
- Nigeria Field Epidemiology and Laboratory Training Programme, Abuja, FCT, Nigeria
- Department of Epidemiology and Medical Statistics, University of Ibadan, Ibadan, Oyo State, Nigeria
| | - IkeOluwapo O. Ajayi
- Nigeria Field Epidemiology and Laboratory Training Programme, Abuja, FCT, Nigeria
- Department of Epidemiology and Medical Statistics, University of Ibadan, Ibadan, Oyo State, Nigeria
| | - Hannah O. Dada-Adegbola
- Department of Medical Microbiology and Parasitology, University of Ibadan, Ibadan, Oyo State, Nigeria
| | - Babatunde O. Adedokun
- Department of Epidemiology and Medical Statistics, University of Ibadan, Ibadan, Oyo State, Nigeria
| | - Muhammad S. Balogun
- Nigeria Field Epidemiology and Laboratory Training Programme, Abuja, FCT, Nigeria
| | - Patrick M. Nguku
- Nigeria Field Epidemiology and Laboratory Training Programme, Abuja, FCT, Nigeria
| | - Olufemi O. Ajumobi
- Nigeria Field Epidemiology and Laboratory Training Programme, Abuja, FCT, Nigeria
- National Malaria Elimination Programme, Abuja, FCT, Nigeria
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