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Saili K, de Jager C, Masaninga F, Chisanga B, Sinyolo A, Chiwaula J, Chirwa J, Hamainza B, Chanda E, Bakyaita NN, Mutero CM. Community perceptions, acceptability, and the durability of house screening interventions against exposure to malaria vectors in Nyimba district, Zambia. BMC Public Health 2024; 24:285. [PMID: 38267927 PMCID: PMC10809574 DOI: 10.1186/s12889-024-17750-4] [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: 07/22/2023] [Accepted: 01/11/2024] [Indexed: 01/26/2024] Open
Abstract
BACKGROUND House screening remains conspicuously absent in national malaria programs despite its recognition by the World Health Organization as a supplementary malaria vector-control intervention. This may be attributed, in part, to the knowledge gap in screen durability or longevity in local climatic conditions and community acceptance under specific cultural practices and socio-economic contexts. The objectives of this study were to assess the durability of window and door wire mesh screens a year after full house screening and to assess the acceptability of the house screening intervention to the participants involved. METHODS This study was conducted in Nyimba district, Zambia and used both quantitative and qualitative methods of data collection and analysis. Both direct observation and questionnaires were employed to assess the durability of the screens and the main reasons for damage. Findings on damage were summarized as percentages. Focus group discussions were used to assess people's knowledge, perceptions, and acceptability of the closing eaves and house screening intervention. Deductive coding and inductive coding were used to analyse the qualitative data. RESULTS A total of 321 out of 400 (80.3%) household owners of screened houses were interviewed. Many window screens (90.3%) were intact. In sharp contrast, most door screens were torn (n = 150; 46.7%) or entirely removed (n = 55; 17.1%). Most doors (n = 114; 76%) had their wire mesh damaged or removed on the bottom half. Goats (25.4%), rust (17.6%) and children (17.1%) were cited most as the cause of damage to door screens. The focus group discussion elicited positive experiences from the participants following the closing of eaves and screening of their windows and doors, ranging from sleeping peacefully due to reduced mosquito biting and/or nuisance and having fewer insects in the house. Participants linked house screening to reduced malaria in their households and community. CONCLUSION This study demonstrated that in rural south-east Zambia, closing eaves and screening windows and doors was widely accepted. Participants perceived that house screening reduced human-vector contact, reduced the malaria burden and nuisance biting from other potentially disease carrying insects. However, screened doors are prone to damage, mainly by children, domestic animals, rust, and termites.
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Affiliation(s)
- Kochelani Saili
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, P.O. Box 30772-00100, Kenya.
- School of Health Systems & Public Health, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa.
| | - Christiaan de Jager
- School of Health Systems & Public Health, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | | | - Brian Chisanga
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, P.O. Box 30772-00100, Kenya
- Development Economics Group, Wageningen University and Research, Wageningen, Netherlands
| | - Andy Sinyolo
- National Malaria Elimination Centre, Lusaka, Zambia
| | | | - Jacob Chirwa
- National Malaria Elimination Centre, Lusaka, Zambia
| | | | - Emmanuel Chanda
- World Health Organization, Regional Office, Brazzaville, Congo
| | | | - Clifford Maina Mutero
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, P.O. Box 30772-00100, Kenya
- School of Health Systems & Public Health, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
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Searle KM, Earland D, Francisco A, Muhiro V, Novela A, Ferrão J. Household structure is independently associated with malaria risk in rural Sussundenga, Mozambique. FRONTIERS IN EPIDEMIOLOGY 2023; 3:1137040. [PMID: 38455901 PMCID: PMC10911029 DOI: 10.3389/fepid.2023.1137040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 07/26/2023] [Indexed: 03/09/2024]
Abstract
Introduction Mozambique has the fourth highest malaria cases and malaria mortality globally. Locally, malaria incidence increases from low in the southern region to high in the central and northern regions. Manica Province in central Mozambique has the fourth highest prevalence of malaria out of the 11 provinces, and the highest in the central region of the country. In this area where coverage of interventions has been limited, household level risk factors can be important for understanding the natural history of infection, as well as the implementation of current and future interventions. There has been indication that the relationship between household structure and malaria risk is actually a mediating one between the true relationship between household income and education and Plasmodium falciparum infection. The objective of this study was to determine and quantify these complex relationships. Methods We conducted a community-based cross-sectional study in Sussundenga village. Sussundenga is a rural village, located in Sussundenga District, Manica Province, Mozambique. We enrolled 303 participants from 83 randomly selected households. We collected information on demographics, household construction, and administered a P. falciparum rapid diagnostic test (RDT). We constructed several generalized estimating equations logistic regression models to determine the independent effects of housing construction on malaria risk. We also constructed models separate from generalized estimating equations logistic mediation models to determine the proportion of effects mediated by household construction material in the relationship between head of household occupation and education and malaria risk. Results The overall malaria prevalence among the study population by RDT was 30.8%. In the multivariable model adjusting for all individual and household factors as potential confounders, rudimentary roof structure was the only household structural variable that was statistically significantly associated with increased malaria risk [OR 2.41 (1.03-5.63)]. We found no evidence that household structure mediated the relationship between head of household education or employment and malaria risk in our study population. Discussion Household structure was a significant risk factor for malaria infection in our study population. These findings are consistent with malaria being a disease of poverty and an area that could be targeted for future interventions that could have long-term impacts.
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Affiliation(s)
- Kelly M. Searle
- Division of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis, MN, United States
| | - Dominique Earland
- Division of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis, MN, United States
| | | | - Valy Muhiro
- Sussundenge-Sede Centro de Saude Rural, Sussundenga, Mozambique
| | - Anisío Novela
- Sussundenge-Sede Centro de Saude Rural, Sussundenga, Mozambique
| | - João Ferrão
- UniSCED Aberta de Mozambique, Chimoio, Mozambique
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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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Chisanga B, Bulte E, Kassie M, Mutero C, Masaninga F, Sangoro OP. The economic impacts of house screening against malaria transmission: Experimental evidence from eastern Zambia. Soc Sci Med 2023; 321:115778. [PMID: 36827904 DOI: 10.1016/j.socscimed.2023.115778] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/21/2023]
Abstract
Malaria imposes an economic burden for human populations in many African countries, and this burden may be reduced through house screening initiatives. We use a randomized controlled trial to measure the economic impacts of house screening against malaria infection. We use a sample of 800 households from 89 villages in rural and peri-urban Zambia to collect baseline data in August 2019 and endline data in August 2020. The main outcome variables are (self-reported) malaria prevalence rates, labor supply, and income, and consider individual and household-level outcomes. House screening reduces malaria prevalence, the number of sick days due to malaria, and the number of malaria episodes. Impacts on adults are more pronounced than on children. In terms of economic impacts, house screening increases labor supply and (household) income. We find particularly large effects on labor supply for women household members. A cost-benefit analysis, based on estimated benefits and measured costs, suggests that the private benefits of house screening exceed the costs. While not all houses are suitable for house screening, we conclude that screening is a promising and cost-effective approach to reduce malaria infections.
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Affiliation(s)
- Brian Chisanga
- Development Economics Group, Wageningen University, the Netherlands.
| | - Erwin Bulte
- Development Economics Group, Wageningen University, the Netherlands.
| | - Menale Kassie
- International Centre of Insect Physiology and Ecology (ICIPE), Kenya.
| | - Clifford Mutero
- International Centre of Insect Physiology and Ecology (ICIPE), Kenya.
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Asale A, Kassie M, Abro Z, Enchalew B, Belay A, Sangoro PO, Tchouassi DP, Mutero CM. The combined impact of LLINs, house screening, and pull-push technology for improved malaria control and livelihoods in rural Ethiopia: study protocol for household randomised controlled trial. BMC Public Health 2022; 22:930. [PMID: 35538444 PMCID: PMC9088127 DOI: 10.1186/s12889-022-12919-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 03/04/2022] [Indexed: 11/23/2022] Open
Abstract
Background The combined application of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are commonly used malaria interventions that target indoor Anopheles vectors. Recent studies on the effects of house screening (HS) and LLINs have demonstrated a reduction in indoor vector densities and malaria when the interventions are combined. In addition, complementary interventions are needed to curb co-occurring pest populations which pose menace to agricultural crop productivity and food security. However, interventions that impact malaria mainly centre on public health strategies, overlooking subtle but important component of agricultural measures. Addressing the coexisting risks of malaria and crop pests could contribute to improved livelihood of communities. Methods A four-armed household, cluster-randomized, controlled study will be conducted to assess the combined impact of HS, LLINs and push-pull agricultural technology (PPT) against clinical malaria in children in Ethiopia. The unit of randomization will be the household, which includes a house and its occupants. A total of 838 households will be enrolled in this study. In this trial 246 households will receive LLINs and HS, 250 will receive LLINs, HS and PPT, 175 households will receive LLINs and PPT. The remaining 167 houses which receive LLINs only will be used as control. One child aged ≤14 years will be enrolled per household in each treatment and followed for clinical malaria using active case detection to estimate malaria incidence for two malaria transmission seasons. Discussion Episodes of clinical malaria, density of indoor biting malaria vectors, sporozoite infection rate, improved crop infestation rate, crop yield gain, livestock productivity and cost effectiveness analysis will be the end points of this study. Socio-economic, social demographic, cost-effectiveness analysis will be conducted using qualitative and participatory methods to explore the acceptability of HS and PPT. Documenting the combined impact of LLINs, HS and PPT on the prevalence of clinical malaria and crop pest damage will be the first of its kind. Trial registration Pan African Clinical Trials Registry, PACTR202006878245287. 24/06/2020. https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=11101. Supplementary Information The online version contains supplementary material available at 10.1186/s12889-022-12919-1.
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Affiliation(s)
- Abebe Asale
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia.
| | - Menale Kassie
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Zewdu Abro
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Bayu Enchalew
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Aklilu Belay
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
| | - Peter O Sangoro
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - David P Tchouassi
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Clifford M Mutero
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
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Asale A, Abro Z, Enchalew B, Teshager A, Belay A, Kassie M, Mutero CM. Community knowledge, perceptions, and practices regarding malaria and its control in Jabi Tehnan district, Amhara Region, Northwest Ethiopia. Malar J 2021; 20:459. [PMID: 34886848 PMCID: PMC8656029 DOI: 10.1186/s12936-021-03996-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 11/28/2021] [Indexed: 11/20/2022] Open
Abstract
Background Use of long-lasting insecticidal nets (LLINs), indoor residual spraying (IRS), community-based malaria education, prompt diagnosis and treatment are key programme components of malaria prevention and control in Ethiopia. However, the effectiveness of these interventions is often undermined by various challenges, including insecticide and drug resistance, the plasticity of malaria vectors feeding and biting behaviour, and certain household factors that lead to misuse and poor utilization of LLINs. The primary objective of this study was to document households’ perceptions towards malaria and assess the prevalence of the disease and the constraints related to the ongoing interventions in Ethiopia (LLINs, IRS, community mobilization house screening). Methods The study was conducted in Jabi Tehnan district, Northwestern Ethiopia, from November 2019 to March 2020. A total of 3010 households from 38 villages were randomly selected for socio-economic and demographic survey. Focus group discussions (FGDs) were conducted in 11 different health clusters considering agro-ecological differences. A total of 1256 children under 10 years of age were screened for malaria parasites using microscopy to determine malaria prevalence. Furthermore, 5-year malaria trend analysis was undertaken based on data obtained from the district health office to understand the disease dynamics. Results Malaria knowledge in the area was high as all FGD participants correctly identified mosquito bites during the night as sources of malaria transmission. Delayed health-seeking behaviour remains a key behavioural challenge in malaria control as it took patients on average 4 days before reporting the case at the nearby health facility. On average, households lost 2.53 working days per person-per malaria episode and they spent US$ 18 per person per episode. Out of the 1256 randomly selected under 10 children tested for malaria parasites, 11 (0.89%) were found to be positive. Malaria disproportionately affected the adult segment of the population more, with 50% of the total cases reported from households being from among individuals who were 15 years or older. The second most affected group was the age group between 5 and 14 years followed by children aged under 5, with 31% and 14% burden, respectively. Conclusion Despite the achievement of universal coverage in terms of LLINs access, utilization of vector control interventions in the area remained low. Using bed nets for unintended purposes remained a major challenge. Therefore, continued community education and communication work should be prioritized in the study area to bring about the desired behavioural changes. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03996-5.
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Affiliation(s)
- Abebe Asale
- International Center of Insect Physiology and Ecology, Addis Ababa, Ethiopia.
| | - Zewdu Abro
- International Center of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Bayu Enchalew
- International Center of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Alayu Teshager
- International Center of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Aklilu Belay
- International Center of Insect Physiology and Ecology, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
| | - Menale Kassie
- International Center of Insect Physiology and Ecology, Nairobi, Kenya
| | - Clifford Maina Mutero
- International Center of Insect Physiology and Ecology, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
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Sangoro OP, Fillinger U, Saili K, Nkya TE, Marubu R, Masaninga F, Trigo SC, Tarumbwa C, Hamainza B, Baltazar C, Mberikunashe J, Chisanga B, Menale K, Chanda E, Mutero CM. Evaluating the efficacy, impact, and feasibility of community-based house screening as a complementary malaria control intervention in southern Africa: a study protocol for a household randomized trial. Trials 2021; 22:883. [PMID: 34872600 PMCID: PMC8646012 DOI: 10.1186/s13063-021-05768-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 10/27/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Concerted effort to control malaria has had a substantial impact on the transmission of the disease in the past two decades. In areas where reduced malaria transmission is being sustained through insecticide-based vector control interventions, primarily long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), non-insecticidal complementary tools will likely be needed to push towards malaria elimination. Once interruption in local disease transmission is achieved, insecticide-based measures can be scaled down gradually and eventually phased out, saving on costs of sustaining control programs and mitigating any unintended negative health and environmental impacts posed by insecticides. These non-insecticidal methods could eventually replace insecticidal methods of vector control. House screening, a non-insecticidal method, has a long history in malaria control, but is still not widely adopted in sub-Saharan Africa. This study aims to add to the evidence base for this intervention in low transmission settings by assessing the efficacy, impact, and feasibility of house screening in areas where LLINs are conventionally used for malaria control. METHODS A two-armed, household randomized clinical trial will be conducted in Mozambique, Zambia, and Zimbabwe to evaluate whether combined the use of house screens and LLINs affords better protection against clinical malaria in children between 6 months and 13 years compared to the sole use of LLINs. Eight hundred households will be enrolled in each study area, where 400 households will be randomly assigned the intervention, house screening, and LLINs while the control households will be provided with LLINs only. Clinical malaria incidence will be estimated by actively following up one child from each household for 6 months over the malaria transmission season. Cross-sectional parasite prevalence will be estimated by testing all participating children for malaria parasites at the beginning and end of each transmission season using rapid diagnostic tests. CDC light traps and pyrethrum spray catches (PSC) will be used to sample adult mosquitoes and evaluate the impact of house screening on indoor mosquito density, species distribution, and sporozoite rates. DISCUSSION This study will contribute epidemiological data on the impact of house screening on malaria transmission and assess the feasibility of its implementation on a programmatic scale. TRIAL REGISTRATION ClinicalTrials.gov PACTR202008524310568 . Registered on August 11, 2020.
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Affiliation(s)
- Onyango P Sangoro
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya.
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Kochelani Saili
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
- School of Health Systems & Public Health, University of Pretoria, Pretoria, South Africa
| | | | - Rose Marubu
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | | | | | | | | | | | | | - Brian Chisanga
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
- Department of Social Sciences, Wageningen University and Research, Wageningen, Netherlands
| | - Kassie Menale
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Emmanuel Chanda
- World Health Organization, Regional Office for Africa, Brazzaville, Congo
| | - Clifford Maina Mutero
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
- School of Health Systems & Public Health, University of Pretoria, Pretoria, South Africa
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Pinder M, Bradley J, Jawara M, Affara M, Conteh L, Correa S, Jeffries D, Jones C, Kandeh B, Knudsen J, Olatunji Y, Sicuri E, D'Alessandro U, Lindsay SW. Improved housing versus usual practice for additional protection against clinical malaria in The Gambia (RooPfs): a household-randomised controlled trial. Lancet Planet Health 2021; 5:e220-e229. [PMID: 33838737 PMCID: PMC8051018 DOI: 10.1016/s2542-5196(21)00002-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND In malaria-endemic areas, residents of modern houses have less malaria than those living in traditional houses. We aimed to assess whether children in The Gambia received an incremental benefit from improved housing, where current best practice of insecticide-treated nets, indoor residual spraying, seasonal malaria chemoprevention in children younger than 5 years, and prompt treatment against clinical malaria was in place. METHODS In this randomised controlled study, 800 households with traditional thatched-roofed houses were randomly selected from 91 villages in the Upper River Region of The Gambia. Within each village, equal numbers of houses were randomly allocated to the control and intervention groups using a sampling frame. Houses in the intervention group were modified with metal roofs and screened doors and windows, whereas houses in the control group received no modifications. In each group, clinical malaria in children aged 6 months to 13 years was monitored by active case detection over 2 years (2016-17). We did monthly collections from indoor light traps to estimate vector densities. Primary endpoints were the incidence of clinical malaria in study children with more than 50% of observations each year and household vector density. The trial is registered at ISRCTN02622179. FINDINGS In June, 2016, 785 houses had one child each recruited into the study (398 in unmodified houses and 402 in modified houses). 26 children in unmodified houses and 28 children in modified houses did not have at least 50% of visits in a year and so were excluded from analysis. 38 children in unmodified houses were recruited after study commencement, as were 21 children in modified houses, meaning 410 children in unmodified houses and 395 in modified houses were included in the parasitological analyses. At the end of the study, 659 (94%) of 702 children were reported to have slept under an insecticide-treated net; 662 (88%) of 755 children lived in houses that received indoor residual spraying; and 151 (90%) of 168 children younger than 5 years had seasonal malaria chemoprevention. Incidence of clinical malaria was 0·12 episodes per child-year in children in the unmodified houses and 0·20 episodes per child-year in the modified houses (unadjusted incidence rate ratio [RR] 1·68 [95% CI 1·11-2·55], p=0·014). Household vector density was 3·30 Anopheles gambiae per house per night in the unmodified houses compared with 3·60 in modified houses (unadjusted RR 1·28 [0·87-1·89], p=0·21). INTERPRETATION Improved housing did not provide protection against clinical malaria in this area of low seasonal transmission with high coverage of insecticide-treated nets, indoor residual spraying, and seasonal malaria chemoprevention. FUNDING Global Health Trials funded by Medical Research Council, UK Department for International Development, and Wellcome Trust.
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Affiliation(s)
- Margaret Pinder
- Department of Biosciences, Durham University, Durham, UK; Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, UK
| | - Musa Jawara
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Muna Affara
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia; Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Lesong Conteh
- London School of Economics and Political Science, London, UK
| | - Simon Correa
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - David Jeffries
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Caroline Jones
- KEMRI-Wellcome Trust Programme, Kilifi, Kenya and Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Balla Kandeh
- National Malaria Control Programme, Banjul, The Gambia
| | - Jakob Knudsen
- Royal Danish Academy - Architecture, Design, Conservation, Copenhagen, Denmark
| | - Yekini Olatunji
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Elisa Sicuri
- School of Public Health, Imperial College London, London, UK; ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia; Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Steve W Lindsay
- Department of Biosciences, Durham University, Durham, UK; Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
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9
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Sternberg ED, Cook J, Alou LPA, Assi SB, Koffi AA, Doudou DT, Aoura CJ, Wolie RZ, Oumbouke WA, Worrall E, Kleinschmidt I, N'Guessan R, Thomas MB. Impact and cost-effectiveness of a lethal house lure against malaria transmission in central Côte d'Ivoire: a two-arm, cluster-randomised controlled trial. Lancet 2021; 397:805-815. [PMID: 33640067 PMCID: PMC7910282 DOI: 10.1016/s0140-6736(21)00250-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 10/15/2020] [Accepted: 01/13/2021] [Indexed: 01/19/2023]
Abstract
BACKGROUND New vector control tools are required to sustain the fight against malaria. Lethal house lures, which target mosquitoes as they attempt to enter houses to blood feed, are one approach. Here we evaluated lethal house lures consisting of In2Care (Wageningen, Netherlands) Eave Tubes, which provide point-source insecticide treatments against host-seeking mosquitoes, in combination with house screening, which aims to reduce mosquito entry. METHODS We did a two-arm, cluster-randomised controlled trial with 40 village-level clusters in central Côte d'Ivoire between Sept 26, 2016, and April 10, 2019. All households received new insecticide-treated nets at universal coverage (one bednet per two people). Suitable households within the clusters assigned to the treatment group were offered screening plus Eave Tubes, with Eave Tubes treated using a 10% wettable powder formulation of the pyrethroid β-cyfluthrin. Because of the nature of the intervention, treatment could not be masked for households and field teams, but all analyses were blinded. The primary endpoint was clinical malaria incidence recorded by active case detection over 2 years in cohorts of children aged 6 months to 10 years. This trial is registered with ISRCTN, ISRCTN18145556. FINDINGS 3022 houses received screening plus Eave Tubes, with an average coverage of 70% across the intervention clusters. 1300 eligible children were recruited for active case detection in the control group and 1260 in the intervention group. During the 2-year follow-up period, malaria case incidence was 2·29 per child-year (95% CI 1·97-2·61) in the control group and 1·43 per child-year (1·21-1·65) in the intervention group (hazard ratio 0·62, 95% CI 0·51-0·76; p<0·0001). Cost-effectiveness simulations suggested that screening plus Eave Tubes has a 74·0% chance of representing a cost-effective intervention, compared with existing healthcare activities in Côte d'Ivoire, and is similarly cost-effective to other core vector control interventions across sub-Saharan Africa. No serious adverse events associated with the intervention were reported during follow-up. INTERPRETATION Screening plus Eave Tubes can provide protection against malaria in addition to the effects of insecticide-treated nets, offering potential for a new, cost-effective strategy to supplement existing vector control tools. Additional trials are needed to confirm these initial results and further optimise Eave Tubes and the lethal house lure concept to facilitate adoption. FUNDING The Bill & Melinda Gates Foundation.
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Affiliation(s)
- Eleanore D Sternberg
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA; Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom.
| | - Jackie Cook
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Ludovic P Ahoua Alou
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Serge Brice Assi
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Alphonsine A Koffi
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Dimi T Doudou
- Laboratoire de Santé, Nutrition et Hygiène, Centre de Recherche pour le Développement, Université Alassane Ouattara, Bouaké, Côte d'Ivoire
| | - Carine J Aoura
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Rosine Z Wolie
- Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire; Laboratoire de genetique, Unité de Formation et de Recherche en Biosciences, Université Felix Houphouët Boigny, Abidjan, Côte d'Ivoire
| | - Welbeck A Oumbouke
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK; Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Eve Worrall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Immo Kleinschmidt
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK; Wits Research Institute for Malaria, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa; Southern African Development Community Malaria Elimination Eight Secretariat, Windhoek, Namibia
| | - Raphael N'Guessan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK; Institut Pierre Richet, Institut National de Santé Publique, Bouaké, Côte d'Ivoire
| | - Matthew B Thomas
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA; York Environmental Sustainability Institute and Department of Biology, University of York, York, UK
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Abstract
BACKGROUND Despite being preventable, malaria remains an important public health problem. The World Health Organization (WHO) reports that overall progress in malaria control has plateaued for the first time since the turn of the century. Researchers and policymakers are therefore exploring alternative and supplementary malaria vector control tools. Research in 1900 indicated that modification of houses may be effective in reducing malaria: this is now being revisited, with new research now examining blocking house mosquito entry points or modifying house construction materials to reduce exposure of inhabitants to infectious bites. OBJECTIVES To assess the effects of house modifications on malaria disease and transmission. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (PubMed); Embase (OVID); Centre for Agriculture and Bioscience International (CAB) Abstracts (Web of Science); and the Latin American and Caribbean Health Science Information database (LILACS), up to 1 November 2019. We also searched the WHO International Clinical Trials Registry Platform (www.who.int/ictrp/search/en/), ClinicalTrials.gov (www.clinicaltrials.gov), and the ISRCTN registry (www.isrctn.com/) to identify ongoing trials up to the same date. SELECTION CRITERIA Randomized controlled trials, including cluster-randomized controlled trials (cRCTs), cross-over studies, and stepped-wedge designs were eligible, as were quasi-experimental trials, including controlled before-and-after studies, controlled interrupted time series, and non-randomized cross-over studies. We only considered studies reporting epidemiological outcomes (malaria case incidence, malaria infection incidence or parasite prevalence). We also summarised qualitative studies conducted alongside included studies. DATA COLLECTION AND ANALYSIS Two review authors selected eligible studies, extracted data, and assessed the risk of bias. We used risk ratios (RR) to compare the effect of the intervention with the control for dichotomous data. For continuous data, we presented the mean difference; and for count and rate data, we used rate ratios. We presented all results with 95% confidence intervals (CIs). We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS Six cRCTs met our inclusion criteria, all conducted in sub-Saharan Africa; three randomized by household, two by village, and one at the community level. All trials assessed screening of windows, doors, eaves, ceilings or any combination of these; this was either alone, or in combination with eave closure, roof modification or eave tube installation (a "lure and kill" device that reduces mosquito entry whilst maintaining some airflow). In two trials, the interventions were insecticide-based. In five trials, the researchers implemented the interventions. The community implemented the interventions in the sixth trial. At the time of writing the review, two of the six trials had published results, both of which compared screened houses (without insecticide) to unscreened houses. One trial in Ethiopia assessed screening of windows and doors. Another trial in the Gambia assessed full screening (screening of eaves, doors and windows), as well as screening of ceilings only. Screening may reduce clinical malaria incidence caused by Plasmodium falciparum (rate ratio 0.38, 95% CI 0.18 to 0.82; 1 trial, 184 participants, 219.3 person-years; low-certainty evidence; Ethiopian study). For malaria parasite prevalence, the point estimate, derived from The Gambia study, was smaller (RR 0.84, 95% CI 0.60 to 1.17; 713 participants, 1 trial; low-certainty evidence), and showed an effect on anaemia (RR 0.61, 95% CI 0.42, 0.89; 705 participants; 1 trial, moderate-certainty evidence). Screening may reduce the entomological inoculation rate (EIR): both trials showed lower estimates in the intervention arm. In the Gambian trial, there was a mean difference in EIR between the control houses and treatment houses ranging from 0.45 to 1.50 (CIs ranged from -0.46 to 2.41; low-certainty evidence), depending on the study year and treatment arm. The Ethiopian trial reported a mean difference in EIR of 4.57, favouring screening (95% CI 3.81 to 5.33; low-certainty evidence). Pooled analysis of the trials showed that individuals living in fully screened houses were slightly less likely to sleep under a bed net (RR 0.84, 95% CI 0.65 to 1.09; 2 trials, 203 participants). In one trial, bed net usage was also lower in individuals living in houses with screened ceilings (RR 0.69, 95% CI 0.50 to 0.95; 1 trial, 135 participants). AUTHORS' CONCLUSIONS Based on the two trials published to date, there is some evidence that screening may reduce malaria transmission and malaria infection in people living in the house. The four trials awaiting publication are likely to enrich the current evidence base, and we will add these to this review when they become available.
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Affiliation(s)
- Joanna Furnival-Adams
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Evelyn A Olanga
- Malaria Alert Centre of the College of Medicine, Blantyre, Malawi
| | - Mark Napier
- Council for Scientific and Industrial Research, Pretoria, South Africa
- Centre for Development Support, University of the Free State, Bloemfontein, South Africa
| | - Paul Garner
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
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11
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Dabira ED, Soumare HM, Lindsay SW, Conteh B, Ceesay F, Bradley J, Kositz C, Broekhuizen H, Kandeh B, Fehr AE, Nieto-Sanchez C, Ribera JM, Peeters Grietens K, Smit MR, Drakeley C, Bousema T, Achan J, D'Alessandro U. Mass Drug Administration With High-Dose Ivermectin and Dihydroartemisinin-Piperaquine for Malaria Elimination in an Area of Low Transmission With High Coverage of Malaria Control Interventions: Protocol for the MASSIV Cluster Randomized Clinical Trial. JMIR Res Protoc 2020; 9:e20904. [PMID: 33211022 PMCID: PMC7714640 DOI: 10.2196/20904] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/28/2020] [Accepted: 08/03/2020] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND With a decline in malaria burden, innovative interventions and tools are required to reduce malaria transmission further. Mass drug administration (MDA) of artemisinin-based combination therapy (ACT) has been identified as a potential tool to further reduce malaria transmission, where coverage of vector control interventions is already high. However, the impact is limited in time. Combining an ACT with an endectocide treatment that is able to reduce vector survival, such as ivermectin (IVM), could increase the impact of MDA and offer a new tool to reduce malaria transmission. OBJECTIVE The study objective is to evaluate the impact of MDA with IVM plus dihydroartemisinin-piperaquine (DP) on malaria transmission in an area with high coverage of malaria control interventions. METHODS The study is a cluster randomized trial in the Upper River Region of The Gambia and included 32 villages (16 control and 16 intervention). A buffer zone of ~2 km was created around all intervention clusters. MDA with IVM plus DP was implemented in all intervention villages and the buffer zones; control villages received standard malaria interventions according to the Gambian National Malaria Control Program plans. RESULTS The MDA campaigns were carried out from August to October 2018 for the first year and from July to September 2019 for the second year. Statistical analysis will commence once the database is completed, cleaned, and locked. CONCLUSIONS This is the first cluster randomized clinical trial of MDA with IVM plus DP. The results will provide evidence on the impact of MDA with IVM plus DP on malaria transmission. TRIAL REGISTRATION ClinicalTrials.gov NCT03576313; https://clinicaltrials.gov/ct2/show/NCT03576313. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID) DERR1-10.2196/20904.
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Affiliation(s)
- Edgard Diniba Dabira
- Medical Research Council Unit Gambia, London School of Hygiene and Tropical Medicine, Banjul, Gambia
| | - Harouna M Soumare
- Medical Research Council Unit Gambia, London School of Hygiene and Tropical Medicine, Banjul, Gambia
| | - Steven W Lindsay
- Department of Biosciences, Durham University, Durham, United Kingdom
| | - Bakary Conteh
- Medical Research Council Unit Gambia, London School of Hygiene and Tropical Medicine, Banjul, Gambia
| | - Fatima Ceesay
- Medical Research Council Unit Gambia, London School of Hygiene and Tropical Medicine, Banjul, Gambia
| | - John Bradley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Christian Kositz
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Balla Kandeh
- National Malaria Control Program, The Gambia, Banjul, Gambia
| | - Alexandra E Fehr
- Medical Anthropology Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
- Vrije Universiteit Amsterdam, Athena Institute, Amsterdam, Netherlands
| | - Claudia Nieto-Sanchez
- Medical Anthropology Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
| | - Joan Muela Ribera
- Medial Anthropology Research Center, Universitat Rovira i Virgili, Tarragona, Spain
| | - Koen Peeters Grietens
- Medical Anthropology Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
| | - Menno Roderick Smit
- Amsterdam Centre for Global Child Health, Emma Children's Hospital, Amsterdam University Medical Centres, Amsterdam, The Netherlands, Amsterdam, Netherlands
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Radboud University Medical Centre, Nijmegen, Netherlands
| | - Jane Achan
- Medical Research Council Unit Gambia, London School of Hygiene and Tropical Medicine, Banjul, Gambia
| | - Umberto D'Alessandro
- Medical Research Council Unit Gambia, London School of Hygiene and Tropical Medicine, Banjul, Gambia
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12
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Abstract
BACKGROUND Despite being preventable, malaria remains an important public health problem. The World Health Organization (WHO) reports that overall progress in malaria control has plateaued for the first time since the turn of the century. Researchers and policymakers are therefore exploring alternative and supplementary malaria vector control tools. Research in 1900 indicated that modification of houses may be effective in reducing malaria: this is now being revisited, with new research now examining blocking house mosquito entry points or modifying house construction materials to reduce exposure of inhabitants to infectious bites. OBJECTIVES To assess the effects of house modifications on malaria disease and transmission. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (PubMed); Embase (OVID); Centre for Agriculture and Bioscience International (CAB) Abstracts (Web of Science); and the Latin American and Caribbean Health Science Information database (LILACS), up to 1 November 2019. We also searched the WHO International Clinical Trials Registry Platform (www.who.int/ictrp/search/en/), ClinicalTrials.gov (www.clinicaltrials.gov), and the ISRCTN registry (www.isrctn.com/) to identify ongoing trials up to the same date. SELECTION CRITERIA Randomized controlled trials, including cluster-randomized controlled trials (cRCTs), cross-over studies, and stepped-wedge designs were eligible, as were quasi-experimental trials, including controlled before-and-after studies, controlled interrupted time series, and non-randomized cross-over studies. We only considered studies reporting epidemiological outcomes (malaria case incidence, malaria infection incidence or parasite prevalence). We also summarised qualitative studies conducted alongside included studies. DATA COLLECTION AND ANALYSIS Two review authors selected eligible studies, extracted data, and assessed the risk of bias. We used risk ratios (RR) to compare the effect of the intervention with the control for dichotomous data. For continuous data, we presented the mean difference; and for count and rate data, we used rate ratios. We presented all results with 95% confidence intervals (CIs). We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS Six cRCTs met our inclusion criteria, all conducted in sub-Saharan Africa; three randomized by household, two by village, and one at the community level. All trials assessed screening of windows, doors, eaves, ceilings or any combination of these; this was either alone, or in combination with eave closure, roof modification or eave tube installation (a "lure and kill" device that reduces mosquito entry whilst maintaining some airflow). In two trials, the interventions were insecticide-based. In five trials, the researchers implemented the interventions. The community implemented the interventions in the sixth trial. At the time of writing the review, two of the six trials had published results, both of which compared screened houses (without insecticide) to unscreened houses. One trial in Ethiopia assessed screening of windows and doors. Another trial in the Gambia assessed full screening (screening of eaves, doors and windows), as well as screening of ceilings only. Screening may reduce clinical malaria incidence caused by Plasmodium falciparum (rate ratio 0.38, 95% CI 0.18 to 0.82; 1 trial, 184 participants, 219.3 person-years; low-certainty evidence; Ethiopian study). For malaria parasite prevalence, the point estimate, derived from The Gambia study, was smaller (RR 0.84, 95% CI 0.60 to 1.17; 713 participants, 1 trial; moderate-certainty evidence), and showed an effect on anaemia (RR 0.61, 95% CI 0.42, 0.89; 705 participants; 1 trial, moderate-certainty evidence). Screening may reduce the entomological inoculation rate (EIR): both trials showed lower estimates in the intervention arm. In the Gambian trial, there was a mean difference in EIR between the control houses and treatment houses ranging from 0.45 to 1.50 (CIs ranged from -0.46 to 2.41; low-certainty evidence), depending on the study year and treatment arm. The Ethiopian trial reported a mean difference in EIR of 4.57, favouring screening (95% CI 3.81 to 5.33; low-certainty evidence). Pooled analysis of the trials showed that individuals living in fully screened houses were slightly less likely to sleep under a bed net (RR 0.84, 95% CI 0.65 to 1.09; 2 trials, 203 participants). In one trial, bed net usage was also lower in individuals living in houses with screened ceilings (RR 0.69, 95% CI 0.50 to 0.95; 1 trial, 135 participants). AUTHORS' CONCLUSIONS Based on the two trials published to date, there is some evidence that screening may reduce malaria transmission and malaria infection in people living in the house. The four trials awaiting publication are likely to enrich the current evidence base, and we will add these to this review when they become available.
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Affiliation(s)
- Joanna Furnival-Adams
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Evelyn A Olanga
- Malaria Alert Centre of the College of Medicine, Blantyre, Malawi
| | - Mark Napier
- Council for Scientific and Industrial Research, Pretoria, South Africa
- Centre for Development Support, University of the Free State, Bloemfontein, South Africa
| | - Paul Garner
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
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13
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Knudsen JB, Pinder M, Jatta E, Jawara M, Yousuf MA, Søndergaard AT, Lindsay SW. Measuring ventilation in different typologies of rural Gambian houses: a pilot experimental study. Malar J 2020; 19:273. [PMID: 32736629 PMCID: PMC7393878 DOI: 10.1186/s12936-020-03327-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/07/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND African houses are frequently too hot and uncomfortable to use a bed net at night. Indoor thermal comfort is often evaluated by measuring temperature and humidity, ignoring ventilation. This study explored ways to measure ventilation in single-roomed rural Gambian houses during the malaria transmission season and evaluated building designs that could increase airflow at night and help keep the occupants comfortable. METHODS Two identical mud-walled houses were constructed with a metal roof, three doors and closed eaves. Experiment 1 compared five methods for measuring ventilation in a building: (1) using a blower door, (2) increasing carbon dioxide (CO2) levels indoors using an artificial source of CO2 and then measuring the rate of gas decay, (3) using a similar approach with a natural source of CO2, (4) measuring the rise of CO2 when people enter a building and (5) using hot-wire anemometers. Experiment 2 used CO2 data loggers to compare ventilation in a reference metal-roofed house with closed eaves and badly-fitting doors with a similar house with (1) thatched roof and open eaves, (2) eaves tubes, (3) screened doors and (4) screened doors and windows. RESULTS In experiment 1, CO2 data loggers placed indoors in two identical houses showed similar changes in airflow (p > 0.05) for all three methods recording either decreasing or increasing CO2. Blower doors were unable to measure airflow in houses with open eaves or screened windows and the anemometers broke down under field conditions. In experiment 2, open eaves in thatched houses, screened doors alone, and screened doors and windows increased indoor ventilation compared to the reference metal-roofed house with closed eaves and badly fitting doors (p < 0.05). Eaves tubes did not increase ventilation in comparison to the reference house. CONCLUSION CO2 data loggers proved to be a simple and efficient method for measuring ventilation in rural houses at night. Ventilation of metal-roofed houses can be improved by adding two screened doors and windows on opposite walls. Improved ventilation will result in increased thermal comfort making it more likely that people will sleep under a bed net.
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Affiliation(s)
- Jakob B Knudsen
- Schools of Architecture, Design and Conservation, The Royal Danish Academy of Fine Arts, Philip de Langes Allé 10, 1435, Copenhagen K, Denmark.
| | - Margaret Pinder
- Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Fajara, The Gambia.,Department of Biosciences, Durham University, Durham, UK
| | - Ebrima Jatta
- Department of Biosciences, Durham University, Durham, UK.,National Malaria Control Programme, Banjul, The Gambia
| | - Musa Jawara
- Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Mahamed A Yousuf
- Schools of Architecture, Design and Conservation, The Royal Danish Academy of Fine Arts, Philip de Langes Allé 10, 1435, Copenhagen K, Denmark
| | - Amalie T Søndergaard
- Schools of Architecture, Design and Conservation, The Royal Danish Academy of Fine Arts, Philip de Langes Allé 10, 1435, Copenhagen K, Denmark
| | - Steve W Lindsay
- Department of Biosciences, Durham University, Durham, UK.,London School of Hygiene & Tropical Medicine, London, UK
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14
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Brew J, Pinder M, D'Alessandro U, Lindsay SW, Jones C, Sicuri E. Evidence of high bed net usage from a list randomization experiments in rural Gambia. Malar J 2020; 19:248. [PMID: 32660475 PMCID: PMC7359605 DOI: 10.1186/s12936-020-03322-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 07/07/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Recording behaviours that have the potential to impact health can be doubly challenging if the behaviour takes place in private spaces that cannot be observed directly, and where respondents answer what they think the recorder may want to hear. Sleeping under a long-lasting insecticidal net (LLIN) is an important intervention for malaria prevention, yet it is difficult to gauge the extent to which coverage (how many nets are in the community) differs from usage (how many people actually sleep under a net). List randomization, a novel method which partially obscures respondents' answers to sensitive questions, was employed to estimate LLIN usage in The Gambia. METHODS 802 heads-of-household from 15 villages were recruited into a randomized controlled trial assessing the effect of a housing intervention on malaria. These houses were randomly assigned to a housing intervention versus control, with stratification by village so as to ensure balance between arms. From these, 125 households (63 intervention, 52 control) were randomly selected for participation in the list randomization experiment, along with 68 households from the same villages but which were not part of the housing improvement study, resulting in a total of 196 households for the list randomization experiment. Approximately half (n = 97) of the 196 study participants were randomly assigned to the control group and received a four-question list about non-sensitive behaviours; the intervention group (n = 99) received the same list, with the addition of one question on a sensitive behaviour: whether or not they had used a bed net the previous night. Participants were read the list of questions and then said how many of the statements were true. Bed net usage was estimated by calculating the difference in means between the number of affirmative responses between the two groups. RESULTS The mean number of affirmative responses in the control group was 2.60 of four statements (95% confidence interval, 95% CI 2.50-2.70), compared with 3.68 (95% CI 3.59-3.78) in the intervention group. Such difference (1.08; 95% CI 94.9-100%) suggests near universal bed net usage. CONCLUSIONS Bed net usage by household heads in these rural villages was found to be high. Though not entirely unexpected given other studies' estimates of high bed net usage in the area, the list randomization method should be further validated in an area with lower coverage.
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Affiliation(s)
- Joe Brew
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain. .,VU University Amsterdam, De Boelelaan 1105, 1081 HV, Amsterdam, The Netherlands.
| | - Margaret Pinder
- Medical Research Council Unit, The Gambia at the London, School of Hygiene and Tropical Medicine, PO Box 273, Banjul, The Gambia.,Department of Biosciences, Durham University, Stockton Road, Durham, DH1 3LE, UK
| | - Umberto D'Alessandro
- Medical Research Council Unit, The Gambia at the London, School of Hygiene and Tropical Medicine, PO Box 273, Banjul, The Gambia
| | - Steven W Lindsay
- Department of Biosciences, Durham University, Stockton Road, Durham, DH1 3LE, UK
| | - Caroline Jones
- Medical Research Council Unit, The Gambia at the London, School of Hygiene and Tropical Medicine, PO Box 273, Banjul, The Gambia
| | - Elisa Sicuri
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.,Health Economics Group, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
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Nguela RL, Bigoga JD, Armel TN, Esther T, Line D, Boris NA, Frederic T, Kazi R, Williams P, Mbacham WF, Leke RGF. The effect of improved housing on indoor mosquito density and exposure to malaria in the rural community of Minkoameyos, Centre Region of Cameroon. Malar J 2020; 19:172. [PMID: 32362282 PMCID: PMC7197188 DOI: 10.1186/s12936-020-03232-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 04/09/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND This study evaluated the effectiveness of improved housing on indoor residual mosquito density and exposure to infected Anophelines in Minkoameyos, a rural community in southern forested Cameroon. METHODS Following the identification of housing factors affecting malaria prevalence in 2013, 218 houses were improved by screening the doors and windows, installing plywood ceilings on open eaves and closing holes on walls and doors. Monthly entomological surveys were conducted in a sample of 21 improved and 21 non-improved houses from November 2014 to October 2015. Mosquitoes sampled from night collections on human volunteers were identified morphologically and their parity status determined. Mosquito infectivity was verified through Plasmodium falciparum CSP ELISA and the average entomological inoculation rates determined. A Reduction Factor (RF), defined as the ratio of the values for mosquitoes collected outdoor to those collected indoor was calculated in improved houses (RFI) and non-improved houses (RFN). An Intervention Effect (IE = RFI/RFN) measured the true effect of the intervention. Chi square test was used to determine variable significance. The threshold for statistical significance was set at P < 0.05. RESULTS A total of 1113 mosquitoes were collected comprising Anopheles sp (58.6%), Culex sp (36.4%), Aedes sp (2.5%), Mansonia sp (2.4%) and Coquillettidia sp (0.2%). Amongst the Anophelines were Anopheles gambiae sensu lato (s.l.) (95.2%), Anopheles funestus (2.9%), Anopheles ziemanni (0.2%), Anopheles brohieri (1.2%) and Anopheles paludis (0.5%). Anopheles gambiae sensu stricto (s.s.) was the only An. gambiae sibling species found. The intervention reduced the indoor Anopheles density by 1.8-fold (RFI = 3.99; RFN = 2.21; P = 0.001). The indoor density of parous Anopheles was reduced by 1.7-fold (RFI = 3.99; RFN = 2.21; P = 0.04) and that of infected Anopheles by 1.8-fold (RFI = 3.26; RFN = 1.78; P = 0.04). Indoor peak biting rates were observed between 02 a.m. to 04 a.m. in non-improved houses and from 02 a.m. to 06 a.m. in improved houses. CONCLUSION Housing improvement contributed to reducing indoor residual anopheline density and malaria transmission. This highlights the need for policy specialists to further evaluate and promote aspects of house design as a complementary control tool that could reduce indoor human-vector contact and malaria transmission in similar epidemiological settings.
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Affiliation(s)
- Rachel L Nguela
- Malaria Consortium-Cameroon Coalition Against Malaria (MC-CCAM), Bastos, PO Box 4256, Yaoundé, Cameroon.
- Department of Public Health, Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon.
- National Reference Unit for Vector Control, The Biotechnology Centre, University of Yaoundé I, Yaoundé, Cameroon.
| | - Jude D Bigoga
- National Reference Unit for Vector Control, The Biotechnology Centre, University of Yaoundé I, Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
| | - Tedjou N Armel
- National Reference Unit for Vector Control, The Biotechnology Centre, University of Yaoundé I, Yaoundé, Cameroon
| | - Tallah Esther
- Malaria Consortium-Cameroon Coalition Against Malaria (MC-CCAM), Bastos, PO Box 4256, Yaoundé, Cameroon
| | - Dongmo Line
- Malaria Consortium-Cameroon Coalition Against Malaria (MC-CCAM), Bastos, PO Box 4256, Yaoundé, Cameroon
| | - Njeambosay A Boris
- National Reference Unit for Vector Control, The Biotechnology Centre, University of Yaoundé I, Yaoundé, Cameroon
| | - Tchouine Frederic
- Malaria Consortium-Cameroon Coalition Against Malaria (MC-CCAM), Bastos, PO Box 4256, Yaoundé, Cameroon
| | - Riksum Kazi
- Architecture for Health in Vulnerable Environments (ARCHIVE Global), New York, USA
| | - Peter Williams
- Architecture for Health in Vulnerable Environments (ARCHIVE Global), New York, USA
| | - Wilfred F Mbacham
- Malaria Consortium-Cameroon Coalition Against Malaria (MC-CCAM), Bastos, PO Box 4256, Yaoundé, Cameroon
- National Reference Unit for Vector Control, The Biotechnology Centre, University of Yaoundé I, Yaoundé, Cameroon
- Department of Biochemistry, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
| | - Rose G F Leke
- Malaria Consortium-Cameroon Coalition Against Malaria (MC-CCAM), Bastos, PO Box 4256, Yaoundé, Cameroon.
- National Reference Unit for Vector Control, The Biotechnology Centre, University of Yaoundé I, Yaoundé, Cameroon.
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16
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Jawara M, Jatta E, Bell D, Burkot TR, Bradley J, Hunt V, Kandeh B, Jones C, Manjang AM, Pinder M, Stone S, D'Alessandro U, Knudsen J, Lindsay SW. New Prototype Screened Doors and Windows for Excluding Mosquitoes from Houses: A Pilot Study in Rural Gambia. Am J Trop Med Hyg 2019; 99:1475-1484. [PMID: 30350770 PMCID: PMC6283509 DOI: 10.4269/ajtmh.18-0660] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Despite compelling evidence that modern housing protects against malaria, houses in endemic areas are still commonly porous to mosquitoes. The protective efficacy of four prototype screened doors and two windows designs against mosquito house entry, their impact on indoor climate, as well as their use, durability and acceptability was assessed in a Gambian village. A baseline survey collected data on all the houses and discrete household units, each consisting of a front and back room, were selected and randomly allocated to the study arms. Each prototype self-closing screened door and window was installed in six and 12 units, respectively, with six unaltered units serving as controls. All prototype doors reduced the number of house-entering mosquitoes by 59–77% in comparison with the control houses. The indoor climate of houses with screened doors was similar to control houses. Seventy-nine percentage of door openings at night occurred from dusk to midnight, when malaria vectors begin entering houses. Ten weeks after installation the doors and windows were in good condition, although 38% of doors did not fully self-close and latch (snap shut). The new doors and windows were popular with residents. The prototype door with perforated concertinaed screening was the best performing door because it reduced mosquito entry, remained fully functional, and was preferred by the villagers. Screened doors and windows may be useful tools for reducing vector exposure and keeping areas malaria-free after elimination, when investment in routine vector control becomes difficult to maintain.
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Affiliation(s)
- Musa Jawara
- Medical Research Council Unit, The Gambia, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Ebrima Jatta
- National Malaria Control Programme, Banjul, The Gambia
| | - David Bell
- Intellectual Ventures Global Good Fund, Bellevue, Washington
| | - Thomas R Burkot
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Australia.,Intellectual Ventures Global Good Fund, Bellevue, Washington
| | - John Bradley
- Department of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Victoria Hunt
- Intellectual Ventures Global Good Fund, Bellevue, Washington
| | - Balla Kandeh
- National Malaria Control Programme, Banjul, The Gambia
| | - Caroline Jones
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom.,KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Aji Matty Manjang
- Medical Research Council Unit, The Gambia, London School of Hygiene and Tropical Medicine, Fajara, The Gambia.,Department of Biosciences, Durham University, Durham, United Kingdom
| | - Margaret Pinder
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom.,Medical Research Council Unit, The Gambia, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Shannon Stone
- Intellectual Ventures Global Good Fund, Bellevue, Washington
| | - Umberto D'Alessandro
- Department of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.,Medical Research Council Unit, The Gambia, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Jakob Knudsen
- The Royal Danish Academy of Fine Arts, School of Architecture, Design and Conservation, The School of Architecture, Copenhagen, Denmark
| | - Steve W Lindsay
- Department of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.,Department of Biosciences, Durham University, Durham, United Kingdom
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17
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Lindsay SW, Jawara M, Mwesigwa J, Achan J, Bayoh N, Bradley J, Kandeh B, Kirby MJ, Knudsen J, Macdonald M, Pinder M, Tusting LS, Weiss DJ, Wilson AL, D'Alessandro U. Reduced mosquito survival in metal-roof houses may contribute to a decline in malaria transmission in sub-Saharan Africa. Sci Rep 2019; 9:7770. [PMID: 31123317 PMCID: PMC6533302 DOI: 10.1038/s41598-019-43816-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 04/27/2019] [Indexed: 11/09/2022] Open
Abstract
In The Gambia, metal-roof houses were hotter during the day than thatched-roof houses. After 24 h, the mortality of Anopheles gambiae, the principal African malaria vector, was 38% higher in metal-roof houses than thatched ones. During the day, mosquitoes in metal-roof houses moved from the hot roof to cooler places near the floor, where the temperature was still high, reaching 35 °C. In laboratory studies, at 35 °C few mosquitoes survived 10 days, the minimum period required for malaria parasite development. Analysis of epidemiological data showed there was less malaria and lower vector survival rates in Gambian villages with a higher proportion of metal roofs. Our findings are consistent with the hypothesis that the indoor climate of metal-roof houses, with higher temperatures and lower humidity, reduces survivorship of indoor-resting mosquitoes and may have contributed to the observed reduction in malaria burden in parts of sub-Saharan Africa.
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Affiliation(s)
- Steve W Lindsay
- Department of Biosciences, Durham University, Durham, DH13LE, UK. .,London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.
| | - Musa Jawara
- Medical Research Council Unit Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Julia Mwesigwa
- Medical Research Council Unit Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Jane Achan
- Medical Research Council Unit Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Nabie Bayoh
- Department of Biosciences, Durham University, Durham, DH13LE, UK.,Adaptive Management and Research Consultants, Kisumu, Kenya
| | - John Bradley
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Balla Kandeh
- National Malaria Control Programme, Banjul, The Gambia
| | - Matthew J Kirby
- Department of Biosciences, Durham University, Durham, DH13LE, UK.,London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Jakob Knudsen
- The Royal Danish Academy of Fine Arts, School of Architecture, Design and Conservation, The School of Architecture, Copenhagen, Denmark
| | | | - Margaret Pinder
- Department of Biosciences, Durham University, Durham, DH13LE, UK.,Medical Research Council Unit Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Lucy S Tusting
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Dan J Weiss
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Anne L Wilson
- Department of Biosciences, Durham University, Durham, DH13LE, UK.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Umberto D'Alessandro
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,Medical Research Council Unit Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
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18
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Morakinyo OM, Balogun FM, Fagbamigbe AF. Housing type and risk of malaria among under-five children in Nigeria: evidence from the malaria indicator survey. Malar J 2018; 17:311. [PMID: 30153834 PMCID: PMC6114872 DOI: 10.1186/s12936-018-2463-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/23/2018] [Indexed: 12/22/2022] Open
Abstract
Background Malaria remains one of the major causes of morbidity and mortality among under-five (U5) children in Nigeria. Though different environmental factors have been assessed to influence the distribution and transmission of malaria vectors, there is a dearth of information on how housing type may influence malaria transmission among U5 children in Nigeria. This study assessed the relationship between housing type and malaria prevalence among U5s in Nigeria. Methods A cross-sectional analysis of the nationally representative 2015 Nigeria malaria indicator survey data was done. A representative sample of 8148 households in 329 clusters was selected for the survey. Children aged 6–59 months in the selected households were tested for anaemia and malaria using the rapid diagnostic test (RDT) and the microscopy. Data were analysed using descriptive statistics, Pearson Chi square (χ2) and logistic regression models at 5% level of significance. Results The odds of malaria infection was significantly higher among older children aged 24–59 months (aOR = 4.8, CI 2.13–10.99, p < 0.001), and children who lived in houses built completely with unimproved materials (aOR = 1.4, CI 1.08–1.80, p = 0.01). Other predictors of malaria infection include living in a rural area (aOR = 1.5, CI 1.25–1.91, p = 0.01), ever slept under a long-lasting insecticide-treated net (aOR = 1.1, CI 0.26–4.79, p = 0.89) and in a room not sprayed with insecticide (aOR = 1.2, CI 0.64–2.31, p = 0.56). Children who were malaria positive showed a higher prevalence of severe anaemia on RDT (87.6%) and Microscopy (67.4%) than those who were not anaemic (RDT = 31.6%, Microscopy = 12.9%). Conclusions Non-improved housing predicted malaria infection among U5s in Nigeria. Improved housing is a promising means to support a more integrated and sustainable approach to malaria prevention. Education of the Nigerian people on the role of improved housing on malaria protection and empowerment of the public to adopt improved housing as well as overall enlightenment on ways to prevent malaria infection can help to augment the current malaria control measures among U5 children.
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Affiliation(s)
- Oyewale M Morakinyo
- Department of Environmental Health Sciences, Faculty of Public Health, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Folusho M Balogun
- Institute of Child Health, College of Medicine, University of Ibadan, Ibadan, Nigeria.
| | - Adeniyi F Fagbamigbe
- Department of Epidemiology and Medical Statistics, Faculty of Public Health, College of Medicine, University of Ibadan, Ibadan, Nigeria
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19
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Sternberg ED, Cook J, Ahoua Alou LP, Aoura CJ, Assi SB, Doudou DT, Koffi AA, N’Guessan R, Oumbouke WA, Smith RA, Worrall E, Kleinschmidt I, Thomas MB. Evaluating the impact of screening plus eave tubes on malaria transmission compared to current best practice in central Côte d'Ivoire: a two armed cluster randomized controlled trial. BMC Public Health 2018; 18:894. [PMID: 30021543 PMCID: PMC6052618 DOI: 10.1186/s12889-018-5746-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 06/25/2018] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Access to long-lasting insecticidal nets (LLINs) has increased and malaria has decreased globally, but malaria transmission remains high in parts of sub-Saharan Africa and insecticide resistance threatens current progress. Eave tubes are a new tool for the targeted delivery of insecticides against mosquitoes attempting to enter houses. The primary objective of this trial is to test whether screening plus eave tubes (SET) provides protection against malaria, on top of universal coverage with LLINs in an area of intense pyrethroid resistance. The trial will also assess acceptability and cost-effectiveness of the intervention. METHODS/DESIGN A two-armed, cluster randomized controlled trial will be conducted to evaluate the effect of SET on clinical malaria incidence in children living in central Côte d'Ivoire. Forty villages will be selected based on population size and the proportion of houses suitable for modification with SET. Using restricted randomization, half the villages will be assigned to the treatment arm (SET + LLINs) and the remainder will be assigned to the control arm (LLINs only). In both arms, LLINs will be distributed and in the treatment arm, householders will be offered SET. Fifty children aged six months to eight years old will be enrolled from randomly selected households in each of the 40 villages. Cohorts will be cleared of malaria parasites at the start of the study and one year after recruitment, and will be monitored for clinical malaria case incidence by active case detection over two years. Mosquito densities will be assessed using CDC light traps and human landing catches and a subset of Anopheles mosquitoes will be examined for parity status and tested for sporozoite infection. Acceptability of SET will be monitored using surveys and focus groups. Cost-effectiveness analysis will measure the incremental cost per case averted and per disability-adjusted life year (DALY) averted of adding SET to LLINs. Economic and financial costs will be estimated from societal and provider perspective using standard economic evaluation methods. DISCUSSION This study will be the first evaluation of the epidemiological impact of SET. Trial findings will show whether SET is a viable, cost-effective technology for malaria control in Côte d'Ivoire and possibly elsewhere. TRIAL REGISTRATION ISRCTN18145556 , registered on 01 February 2017 - retrospectively registered.
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Affiliation(s)
- Eleanore D. Sternberg
- Department of Entomology and Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, 16802 PA USA
| | - Jackie Cook
- MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Ludovic P. Ahoua Alou
- Institut Pierre Richet (IPR) / Institut National de Santé Publique (INSP), Bouaké, Côte d’Ivoire
| | - Carine J. Aoura
- Institut Pierre Richet (IPR) / Institut National de Santé Publique (INSP), Bouaké, Côte d’Ivoire
| | - Serge Brice Assi
- Institut Pierre Richet (IPR) / Institut National de Santé Publique (INSP), Bouaké, Côte d’Ivoire
| | | | - A. Alphonsine Koffi
- Institut Pierre Richet (IPR) / Institut National de Santé Publique (INSP), Bouaké, Côte d’Ivoire
| | - Raphael N’Guessan
- Institut Pierre Richet (IPR) / Institut National de Santé Publique (INSP), Bouaké, Côte d’Ivoire
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Welbeck A. Oumbouke
- Institut Pierre Richet (IPR) / Institut National de Santé Publique (INSP), Bouaké, Côte d’Ivoire
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Rachel A. Smith
- Department of Communication Arts and Sciences and Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, 16802 PA USA
| | - Eve Worrall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Immo Kleinschmidt
- MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Matthew B. Thomas
- Department of Entomology and Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, 16802 PA USA
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20
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Mburu MM, Juurlink M, Spitzen J, Moraga P, Hiscox A, Mzilahowa T, Takken W, McCann RS. Impact of partially and fully closed eaves on house entry rates by mosquitoes. Parasit Vectors 2018; 11:383. [PMID: 29970153 PMCID: PMC6029021 DOI: 10.1186/s13071-018-2977-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/25/2018] [Indexed: 12/02/2022] Open
Abstract
Background Most people infected with malaria acquire the infection indoors from mosquito vectors that entered the house through open eaves, windows and doors. Structural house improvement (e.g. closed eaves and screened windows) is an established method of reducing mosquito entry. It could be complementary to other interventions such as insecticide-treated bed nets (ITNs) for malaria control because it covers and protects all individuals in a house equally. However, when implemented at a large scale, house improvement may not be employed optimally. It is therefore critical to assess whether partial house improvement will have any effect on mosquito house entry. We investigated the effect of partial and complete eave closure on the house-entry rates of malaria vectors and other mosquitoes in southern Malawi. Methods The study was conducted for 25 nights in May-June 2016. Twenty-five traditional houses were modified according to five treatments: fully closed eaves, three different levels of partially closed eaves, and open eaves. All houses had fully screened windows and closed doors. Host-seeking mosquitoes were sampled inside these houses using Centers for Disease Control and Prevention (CDC) light traps. The effect of open eaves versus partial or complete eave closure on the number of mosquitoes trapped inside the house was estimated using a generalized linear mixed model fitted with Poisson distribution and a log-link function. Results House entry by malaria vectors was 14-times higher in houses with fully open eaves compared to houses with fully closed eaves adjusting for wall-type, number of people that slept in the house the previous night, cooking locations and presence of livestock. Houses with four small openings had 9 times more malaria vectors compared to houses with fully closed eaves. The catches of culicine mosquitoes caught in houses with fully closed eaves were not different from those caught in houses with the other treatments. Conclusions Closed eaves resulted in fewer malaria vectors in houses, with differences depending on the degree of eave closure. The ability of malaria vectors to locate any remaining entry points on improved houses, as demonstrated here, suggests that quality control must be an important component of implementing house improvement as an intervention.The lack of effect on culicine mosquitoes in this study could reduce acceptance of house improvement, as implemented here, by household residents due to continued nuisance biting. This limitation could be addressed through community engagement (e.g. encouraging people to close their doors early in the evenings) or improved designs.
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Affiliation(s)
- Monicah M Mburu
- Wageningen University and Research, Wageningen, The Netherlands. .,College of Medicine, University of Malawi, Zomba, Malawi.
| | - Malou Juurlink
- Wageningen University and Research, Wageningen, The Netherlands
| | - Jeroen Spitzen
- Wageningen University and Research, Wageningen, The Netherlands
| | - Paula Moraga
- Centre for Health Informatics, Computing and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, UK
| | | | - Themba Mzilahowa
- College of Medicine, University of Malawi, Zomba, Malawi.,MAC Communicable Diseases Action Centre, College of Medicine, Blantyre, Malawi
| | - Willem Takken
- Wageningen University and Research, Wageningen, The Netherlands
| | - Robert S McCann
- Wageningen University and Research, Wageningen, The Netherlands.,College of Medicine, University of Malawi, Zomba, Malawi
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21
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Williams YA, Tusting LS, Hocini S, Graves PM, Killeen GF, Kleinschmidt I, Okumu FO, Feachem RGA, Tatarsky A, Gosling RD. Expanding the Vector Control Toolbox for Malaria Elimination: A Systematic Review of the Evidence. ADVANCES IN PARASITOLOGY 2018; 99:345-379. [PMID: 29530309 DOI: 10.1016/bs.apar.2018.01.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Additional vector control tools (VCTs) are needed to supplement insecticide-treated nets (ITNs) and indoor residual spraying (IRS) to achieve malaria elimination in many settings. To identify options for expanding the malaria vector control toolbox, we conducted a systematic review of the availability and quality of the evidence for 21 malaria VCTs, excluding ITNs and IRS. METHODS Six electronic databases and grey literature sources were searched from January 1, 1980 to September 28, 2015 to identify systematic reviews, Phase I-IV studies, and observational studies that measured the effect of malaria VCTs on epidemiological or entomological outcomes across any age groups in all malaria-endemic settings. Eligible studies were summarized qualitatively, with quality and risk of bias assessments undertaken where possible. Of 17,912 studies screened, 155 were eligible for inclusion and were included in a qualitative synthesis. RESULTS Across the 21 VCTs, we found considerable heterogeneity in the volume and quality of evidence, with 7 VCTs currently supported by at least one Phase III community-level evaluation measuring parasitologically confirmed malaria incidence or infection prevalence (insecticide-treated clothing and blankets, insecticide-treated hammocks, insecticide-treated livestock, larval source management (LSM), mosquito-proofed housing, spatial repellents, and topical repellents). The remaining VCTs were supported by one or more Phase II (n=13) or Phase I evaluation (n=1). Overall the quality of the evidence base remains greatest for LSM and topical repellents, relative to the other VCTs evaluated, although existing evidence indicates that topical repellents are unlikely to provide effective population-level protection against malaria. CONCLUSIONS Despite substantial gaps in the supporting evidence, several VCTs may be promising supplements to ITNs and IRS in appropriate settings. Strengthening operational capacity and research to implement underutilized VCTs, such as LSM and mosquito-proofed housing, using an adaptive, learning-by-doing approach, while expanding the evidence base for promising supplementary VCTs that are locally tailored, should be considered central to global malaria elimination efforts.
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Affiliation(s)
- Yasmin A Williams
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, United States.
| | - Lucy S Tusting
- Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Sophia Hocini
- Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Patricia M Graves
- College of Public Health, Medical and Veterinary Sciences and Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, QLD, Australia
| | - Gerry F Killeen
- Ifakara Health Institute, Ifakara, Tanzania; Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Immo Kleinschmidt
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom; School of Pathology, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa; Elimination 8, Windhoek, Namibia
| | | | - Richard G A Feachem
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, United States
| | - Allison Tatarsky
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, United States
| | - Roly D Gosling
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, United States
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22
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von Seidlein L, Ikonomidis K, Mshamu S, Nkya TE, Mukaka M, Pell C, Lindsay SW, Deen JL, Kisinza WN, Knudsen JB. Affordable house designs to improve health in rural Africa: a field study from northeastern Tanzania. Lancet Planet Health 2017; 1:e188-e199. [PMID: 29851640 DOI: 10.1016/s2542-5196(17)30078-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/05/2017] [Accepted: 07/11/2017] [Indexed: 06/08/2023]
Abstract
BACKGROUND The population of sub-Saharan Africa is currently estimated to be 1245 million and is expected to quadruple by the end of the century, necessitating the building of millions of homes. Malaria remains a substantial problem in this region and efforts to minimise transmission should be considered in future house planning. We studied how building elements, which have been successfully employed in southeast Asia to prevent mosquitos from entering and cooling the house, could be integrated in a more sustainable house design in rural northeastern Tanzania, Africa, to decrease mosquito density and regulate indoor climate. METHODS In this field study, six prototype houses of southeast Asian design were built in in the village of Magoda in Muheza District, Tanga Region, Tanzania, and compared with modified and unmodified, traditional, sub-Saharan African houses. Prototype houses were built with walls made of lightweight permeable materials (bamboo, shade net, or timber) with bedrooms elevated from the ground and with screened windows. Modified and unmodified traditional African houses, wattle-daub or mud-block constructions, built on the ground with poor ventilation served as controls. In the modified houses, major structural problems such as leaking roofs were repaired, windows screened, open eaves blocked with bricks and mortar, cement floors repaired or constructed, and rain gutters and a tank for water storage added. Prototype houses were randomly allocated to village households through a free, fair, and transparent lottery. The lottery tickets were deposited in a bucket made of transparent plastic. Each participant could draw one ticket. Hourly measurements of indoor temperature and humidity were recorded in all study houses with data loggers and mosquitoes were collected indoors and outdoors using Furvela tent traps and were identified with standard taxonomic keys. Mosquitoes of the Anopheles gambiae complex were identified to species using PCR. Attitudes towards the new house design were assessed 6-9 months after the residents moved into their new or modified homes through 15 in-depth interviews with household heads of the new houses and five focus group discussions including neighbours of each group of prototype housing. FINDINGS Between July, 2014, and July, 2015, six prototype houses were constructed; one single and one double storey building with each of the following claddings: bamboo, shade net, and timber. The overall reduction of all mosquitoes caught was highest in the double-storey buildings (96%; 95% CI 92-98) followed closely by the reduction found in single-storey buildings (77%; 72-82) and lowest in the modified reference houses (43%; 36-50) and unmodified reference houses (23%; 18-29). The indoor temperature in the new design houses was 2·3°C (95% CI 2·2-2·4) cooler than in the reference houses. While both single and two-storey buildings provided a cooler indoor climate than did traditional housing, two-story buildings provided the biggest reduction in mosquito densities (96%, 95% CI 89-100). Seven people who moved into the prototype houses and seven of their neighbours (three of whom had their houses modified) participated in in-depth interviews. After living in their new prototype houses for 6-9 months, residents expressed satisfaction with the new design, especially the second-storey sleeping area because of the privacy and security of upstairs bedrooms. INTERPRETATION The new design houses had fewer mosquitoes and were cooler than modified and unmodified traditional homes. New house designs are an underused intervention and hold promise to reduce malaria transmission in sub-Saharan Africa and keep areas malaria-free after elimination. FUNDING Ruth W Jensens Foundation, Copenhagen and Hanako Foundation, Singapore.
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Affiliation(s)
- Lorenz von Seidlein
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | | | | | - Theresia E Nkya
- The National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Mavuto Mukaka
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Christopher Pell
- Centre for Social Science and Global Health, University of Amsterdam, Amsterdam, the Netherlands; Amsterdam Institute for Global Health and Development, Amsterdam, the Netherlands
| | - Steven W Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, UK
| | - Jacqueline L Deen
- Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines, Manila, Philippines
| | - William N Kisinza
- The National Institute for Medical Research, Amani Medical Research Centre, Muheza, Tanzania
| | - Jakob B Knudsen
- Ingvartsen Arkitekter, København K, Denmark; Det Kongelige Danske Kunstakademis Skoler for Arkitektur, Design og Konservering-Arkitektskolen, Copenhagen, Denmark
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23
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Dlamini N, Hsiang MS, Ntshalintshali N, Pindolia D, Allen R, Nhlabathi N, Novotny J, Kang Dufour MS, Midekisa A, Gosling R, LeMenach A, Cohen J, Dorsey G, Greenhouse B, Kunene S. Low-Quality Housing Is Associated With Increased Risk of Malaria Infection: A National Population-Based Study From the Low Transmission Setting of Swaziland. Open Forum Infect Dis 2017; 4:ofx071. [PMID: 28580365 PMCID: PMC5447662 DOI: 10.1093/ofid/ofx071] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 04/04/2017] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Low-quality housing may confer risk of malaria infection, but evidence in low transmission settings is limited. METHODS To examine the relationship between individual level housing quality and locally acquired infection in children and adults, a population-based cross-sectional analysis was performed using existing surveillance data from the low transmission setting of Swaziland. From 2012 to 2015, cases were identified through standard diagnostics in health facilities and by loop-mediated isothermal amplification in active surveillance, with uninfected subjects being household members and neighbors. Housing was visually assessed in a home visit and then classified as low, high, or medium quality, based on housing components being traditional, modern, or both, respectively. RESULTS Overall, 11426 individuals were included in the study: 10960 uninfected and 466 infected (301 symptomatic and 165 asymptomatic). Six percent resided in low-quality houses, 26% in medium-quality houses, and 68% in high-quality houses. In adjusted models, low- and medium-quality construction was associated with increased risk of malaria compared with high-quality construction (adjusted odds ratio [AOR], 2.11 and 95% confidence interval [CI], 1.26-3.53 for low vs high; AOR, 1.56 and 95% CI, 1.15-2.11 for medium vs high). The relationship was independent of vector control, which also conferred a protective effect (AOR, 0.67; 95% CI, .50-.90) for sleeping under an insecticide-treated bed net or a sprayed structure compared with neither. CONCLUSIONS Our study adds to the limited literature on housing quality and malaria risk from low transmission settings. Housing improvements may offer an attractive and sustainable additional strategy to support countries in malaria elimination.
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Affiliation(s)
| | - Michelle S Hsiang
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas.,Malaria Elimination Initiative, Global Health Group, and Departments of.,Pediatrics and
| | | | | | - Regan Allen
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas
| | | | | | | | | | - Roly Gosling
- Malaria Elimination Initiative, Global Health Group, and Departments of
| | | | - Justin Cohen
- Clinton Health Access Initiative, Boston, Massachusetts
| | - Grant Dorsey
- Medicine, University of California San Francisco; and
| | | | - Simon Kunene
- Swaziland National Malaria Control Programme, Manzini
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24
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Alegana VA, Kigozi SP, Nankabirwa J, Arinaitwe E, Kigozi R, Mawejje H, Kilama M, Ruktanonchai NW, Ruktanonchai CW, Drakeley C, Lindsay SW, Greenhouse B, Kamya MR, Smith DL, Atkinson PM, Dorsey G, Tatem AJ. Spatio-temporal analysis of malaria vector density from baseline through intervention in a high transmission setting. Parasit Vectors 2016; 9:637. [PMID: 27955677 PMCID: PMC5153881 DOI: 10.1186/s13071-016-1917-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 11/28/2016] [Indexed: 11/24/2022] Open
Abstract
Background An increase in effective malaria control since 2000 has contributed to a decline in global malaria morbidity and mortality. Knowing when and how existing interventions could be combined to maximise their impact on malaria vectors can provide valuable information for national malaria control programs in different malaria endemic settings. Here, we assess the effect of indoor residual spraying on malaria vector densities in a high malaria endemic setting in eastern Uganda as part of a cohort study where the use of long-lasting insecticidal nets (LLINs) was high. Methods Anopheles mosquitoes were sampled monthly using CDC light traps in 107 households selected randomly. Information on the use of malaria interventions in households was also gathered and recorded via a questionnaire. A Bayesian spatio-temporal model was then used to estimate mosquito densities adjusting for climatic and ecological variables and interventions. Results Anopheles gambiae (sensu lato) were most abundant (89.1%; n = 119,008) compared to An. funestus (sensu lato) (10.1%, n = 13,529). Modelling results suggest that the addition of indoor residual spraying (bendiocarb) in an area with high coverage of permethrin-impregnated LLINs (99%) was associated with a major decrease in mosquito vector densities. The impact on An. funestus (s.l.) (Rate Ratio 0.1508; 97.5% CI: 0.0144–0.8495) was twice as great as for An. gambiae (s.l.) (RR 0.5941; 97.5% CI: 0.1432–0.8577). Conclusions High coverage of active ingredients on walls depressed vector populations in intense malaria transmission settings. Sustained use of combined interventions would have a long-term impact on mosquito densities, limiting infectious biting. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1917-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Victor A Alegana
- WorldPop, Geography and Environment, University of Southampton, Southampton, UK. .,Flowminder Foundation, Stockholm, Sweden.
| | - Simon P Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda.,London School of Hygiene and Tropical Medicine, London, UK
| | - Joaniter Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | - Ruth Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Henry Mawejje
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Maxwell Kilama
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Nick W Ruktanonchai
- WorldPop, Geography and Environment, University of Southampton, Southampton, UK.,Flowminder Foundation, Stockholm, Sweden
| | - Corrine W Ruktanonchai
- WorldPop, Geography and Environment, University of Southampton, Southampton, UK.,Flowminder Foundation, Stockholm, Sweden
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, UK
| | - Steve W Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, UK
| | - Bryan Greenhouse
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - David L Smith
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, USA
| | - Peter M Atkinson
- WorldPop, Geography and Environment, University of Southampton, Southampton, UK.,Faculty of Science and Technology, Lancaster University, Lancaster, UK.,School of Geography, Archaeology and Palaeoecology, Queen's University Belfast, Belfast, BT7 1NN, Northern Ireland, UK
| | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA
| | - Andrew J Tatem
- WorldPop, Geography and Environment, University of Southampton, Southampton, UK.,Flowminder Foundation, Stockholm, Sweden
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