1
|
Kearney EA, Amratia P, Kang SY, Agius PA, Alene KA, O'Flaherty K, Oo WH, Cutts JC, Htike W, Da Silva Goncalves D, Razook Z, Barry AE, Drew D, Thi A, Aung KZ, Thu HK, Thein MM, Zaw NN, Htay WYM, Soe AP, Beeson JG, Simpson JA, Gething PW, Cameron E, Fowkes FJI. Geospatial joint modeling of vector and parasite serology to microstratify malaria transmission. Proc Natl Acad Sci U S A 2024; 121:e2320898121. [PMID: 38833464 DOI: 10.1073/pnas.2320898121] [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: 11/28/2023] [Accepted: 04/30/2024] [Indexed: 06/06/2024] Open
Abstract
The World Health Organization identifies a strong surveillance system for malaria and its mosquito vector as an essential pillar of the malaria elimination agenda. Anopheles salivary antibodies are emerging biomarkers of exposure to mosquito bites that potentially overcome sensitivity and logistical constraints of traditional entomological surveys. Using samples collected by a village health volunteer network in 104 villages in Southeast Myanmar during routine surveillance, the present study employs a Bayesian geostatistical modeling framework, incorporating climatic and environmental variables together with Anopheles salivary antigen serology, to generate spatially continuous predictive maps of Anopheles biting exposure. Our maps quantify fine-scale spatial and temporal heterogeneity in Anopheles salivary antibody seroprevalence (ranging from 9 to 99%) that serves as a proxy of exposure to Anopheles bites and advances current static maps of only Anopheles occurrence. We also developed an innovative framework to perform surveillance of malaria transmission. By incorporating antibodies against the vector and the transmissible form of malaria (sporozoite) in a joint Bayesian geostatistical model, we predict several foci of ongoing transmission. In our study, we demonstrate that antibodies specific for Anopheles salivary and sporozoite antigens are a logistically feasible metric with which to quantify and characterize heterogeneity in exposure to vector bites and malaria transmission. These approaches could readily be scaled up into existing village health volunteer surveillance networks to identify foci of residual malaria transmission, which could be targeted with supplementary interventions to accelerate progress toward elimination.
Collapse
Affiliation(s)
- Ellen A Kearney
- Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Punam Amratia
- Malaria Atlas Project, Telethon Kids Institute, Perth, WA 6009, Australia
| | - Su Yun Kang
- Malaria Atlas Project, Telethon Kids Institute, Perth, WA 6009, Australia
| | - Paul A Agius
- Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, VIC 3010, Australia
- Biostatistics Unit, Faculty of Health, Deakin University, Melbourne, VIC 3125, Australia
| | - Kefyalew Addis Alene
- Malaria Atlas Project, Telethon Kids Institute, Perth, WA 6009, Australia
- Faculty of Health Sciences, Curtin University, Perth, WA 6102, Australia
| | | | - Win Han Oo
- Health Security and Malaria Program, Burnet Institute Myanmar, Yangon 11201, Myanmar
| | - Julia C Cutts
- Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004, Australia
- Department of Medicine at the Doherty Institute, The University of Melbourne, Melbourne, VIC 3000, Australia
| | - Win Htike
- Health Security and Malaria Program, Burnet Institute Myanmar, Yangon 11201, Myanmar
| | | | - Zahra Razook
- Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004, Australia
- Institute for Physical and Mental Health and Clinical Translation, School of Medicine, Deakin University, Geelong, VIC 3216, Australia
| | - Alyssa E Barry
- Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004, Australia
- Institute for Physical and Mental Health and Clinical Translation, School of Medicine, Deakin University, Geelong, VIC 3216, Australia
| | - Damien Drew
- Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004, Australia
| | - Aung Thi
- Department of Public Health, Myanmar Ministry of Health and Sports, Nay Pyi Taw 15011, Myanmar
| | - Kyaw Zayar Aung
- Health Security and Malaria Program, Burnet Institute Myanmar, Yangon 11201, Myanmar
| | - Htin Kyaw Thu
- Health Security and Malaria Program, Burnet Institute Myanmar, Yangon 11201, Myanmar
| | - Myat Mon Thein
- Health Security and Malaria Program, Burnet Institute Myanmar, Yangon 11201, Myanmar
| | - Nyi Nyi Zaw
- Health Security and Malaria Program, Burnet Institute Myanmar, Yangon 11201, Myanmar
| | - Wai Yan Min Htay
- Health Security and Malaria Program, Burnet Institute Myanmar, Yangon 11201, Myanmar
| | - Aung Paing Soe
- Health Security and Malaria Program, Burnet Institute Myanmar, Yangon 11201, Myanmar
| | - James G Beeson
- Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004, Australia
- Department of Infectious Diseases, The University of Melbourne, Melbourne, VIC 3000, Australia
- Department of Microbiology, Monash University, Melbourne, VIC 3800, Australia
- Central Clinical School, Monash University, Melbourne, VIC 3004, Australia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Peter W Gething
- Malaria Atlas Project, Telethon Kids Institute, Perth, WA 6009, Australia
- Faculty of Health Sciences, Curtin University, Perth, WA 6102, Australia
| | - Ewan Cameron
- Malaria Atlas Project, Telethon Kids Institute, Perth, WA 6009, Australia
- Faculty of Health Sciences, Curtin University, Perth, WA 6102, Australia
| | - Freya J I Fowkes
- Disease Elimination Program, Burnet Institute, Melbourne, VIC 3004, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, VIC 3010, Australia
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC 3004, Australia
| |
Collapse
|
2
|
Tizifa TA, Kabaghe AN, McCann RS, Gowelo S, Malenga T, Nkhata RM, Chapeta Y, Nkhono W, Kadama A, Takken W, Phiri KS, van Vugt M, van den Berg H, Manda-Taylor L. Assessing the implementation fidelity, feasibility, and sustainability of community-based house improvement for malaria control in southern Malawi: a mixed-methods study. BMC Public Health 2024; 24:951. [PMID: 38566043 PMCID: PMC10988826 DOI: 10.1186/s12889-024-18401-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 03/20/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Despite significant success in the fight against malaria over the past two decades, malaria control programmes rely on only two insecticidal methods: indoor residual spraying and insecticidal-treated nets. House improvement (HI) can complement these interventions by reducing human-mosquito contact, thereby reinforcing the gains in disease reduction. This study assessed the implementation fidelity, which is the assessment of how closely an intervention aligns with its intended design, feasibility, and sustainability of community-led HI in southern Malawi. METHODS The study, conducted in 22 villages (2730 households), employed a mixed-methods approach. Implementation fidelity was assessed using a modified framework, with longitudinal surveys collecting data on HI coverage indicators. Quantitative analysis, employing descriptive statistics, evaluated the adherence to HI implementation. Qualitative data came from in-depth interviews, key informant interviews, and focus groups involving project beneficiaries and implementers. Qualitative data were analysed using content analysis guided by the implementation fidelity model to explore facilitators, challenges, and factors affecting intervention feasibility. RESULTS The results show that HI was implemented as planned. There was good adherence to the intended community-led HI design; however, the adherence could have been higher but gradually declined over time. In terms of intervention implementation, 74% of houses had attempted to have eaves closed in 2016-17 and 2017-18, compared to 70% in 2018-19. In 2016-17, 42% of houses had all four sides of the eaves closed, compared to 33% in 2018-19. Approximately 72% of houses were screened with gauze wire in 2016-17, compared to 57% in 2018-19. High costs, supply shortages, labour demands, volunteers' poor living conditions and adverse weather were reported to hinder the ideal HI implementation. Overall, the community described community-led HI as feasible and could be sustained by addressing these socioeconomic and contextual challenges. CONCLUSION Our study found that although HI was initially implemented as planned, its fidelity declined over time. Using trained volunteers facilitated the fidelity and feasibility of implementing the intervention. A combination of rigorous community education, consistent training, information, education and communication, and intervention modifications may be necessary to address the challenges and enhance the intervention's fidelity, feasibility, and sustainability.
Collapse
Affiliation(s)
- Tinashe A Tizifa
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, University of Amsterdam, Amsterdam University Medical Center, Location Academic Medical Center, Amsterdam, The Netherlands.
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.
| | - Alinune N Kabaghe
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Robert S McCann
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- Centre for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, USA
| | - Steven Gowelo
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Tumaini Malenga
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- National TB and Leprosy Elimination Programme, Ministry of Health, Lilongwe, Malawi
| | - Richard M Nkhata
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Yankho Chapeta
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Biological Sciences Department, Mzuzu University, Mzuzu, Malawi
| | - William Nkhono
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Asante Kadama
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Kamija S Phiri
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Michele van Vugt
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, University of Amsterdam, Amsterdam University Medical Center, Location Academic Medical Center, Amsterdam, The Netherlands
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Lucinda Manda-Taylor
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| |
Collapse
|
3
|
Singogo E, Chagomerana M, Van Ryn C, M’bwana R, Likaka A, M’baya B, Puerto-Meredith S, Chipeta E, Mwapasa V, Muula A, Reilly C, Hosseinipour MC. Prevalence and incidence of transfusion-transmissible infections among blood donors in Malawi: A population-level study. Transfus Med 2023; 33:483-496. [PMID: 37828838 PMCID: PMC11096640 DOI: 10.1111/tme.13006] [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: 11/30/2022] [Revised: 08/04/2023] [Accepted: 09/09/2023] [Indexed: 10/14/2023]
Abstract
BACKGROUND Voluntary non-remunerated blood donors (VNRBDs) are essential to sustain national blood supplies. Expanding testing capacity for the major transfusion-transmitted infections (TTI) is crucial to ensure safe blood products. Understanding trends in TTIs can inform prioritisation of resources. METHODS We conducted a retrospective cohort data analysis of routine blood donation data collected from VNRBDs by the Malawi Blood Transfusion Service from January 2015 to October 2021. Variables included age, occupation; and screening results of TTIs (HIV, Hepatitis B and C, and syphilis). We estimated both prevalence and incidence per person-year for each TTI using longitudinal and spatial logistic regression models. RESULTS Of the 213 626 donors, 204 920 (95.8%) donors were included in the final analysis. Most donors (77.4%) were males, baseline median age was 19.9 (IQR 18.0, 24.1), 70.9% were students, and over 80.0% were single at first donation. Overall TTI prevalence among donors was 10.7%, with HBV having the highest prevalence (3.4%), followed by syphilis (3.3%), then HIV (2.4%) and HCV (2.4%). Incidence per 1000 person-years for syphilis was 20.1 (19.0, 21.3), HCV was 18.4 (17.3, 19.5), HBV was 13.7 (12.8, 14.7), and HIV was 11.4 (10.6, 12.3). We noted geographical variations with the northern region having lower rates of both prevalence and incidence compared to central and southern regions. CONCLUSION The individual TTI prevalence and incidence rates from this study are consistent with Southern African regional estimates. By identifying geographical variations of TTI prevalence and incidence, these findings could potentially inform prioritisation of blood collection efforts to optimise blood collection processes.
Collapse
Affiliation(s)
| | | | - Collin Van Ryn
- Department of Biostatistics, University of Minnesota Twin Cities, Minneapolis, Minnesota, USA
| | | | | | | | | | - Effie Chipeta
- Centre for Reproductive Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Victor Mwapasa
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Adamson Muula
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Cavan Reilly
- Department of Biostatistics, University of Minnesota Twin Cities, Minneapolis, Minnesota, USA
| | - Mina C. Hosseinipour
- UNC Project, Lilongwe, Malawi
- Division of Infectious Diseases, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | | |
Collapse
|
4
|
Mayor A, Ishengoma DS, Proctor JL, Verity R. Sampling for malaria molecular surveillance. Trends Parasitol 2023; 39:954-968. [PMID: 37730525 PMCID: PMC10580323 DOI: 10.1016/j.pt.2023.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/22/2023] [Accepted: 08/23/2023] [Indexed: 09/22/2023]
Abstract
Strategic use of Plasmodium falciparum genetic variation has great potential to inform public health actions for malaria control and elimination. Malaria molecular surveillance (MMS) begins with a strategy to identify and collect parasite samples, guided by public-health priorities. In this review we discuss sampling design practices for MMS and point out epidemiological, biological, and statistical factors that need to be considered. We present examples for different use cases, including detecting emergence and spread of rare variants, establishing transmission sources and inferring changes in malaria transmission intensity. This review will potentially guide the collection of samples and data, serve as a starting point for further methodological innovation, and enhance utilization of MMS to support malaria elimination.
Collapse
Affiliation(s)
- Alfredo Mayor
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain; Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique; Department of Physiologic Sciences, Faculty of Medicine, Universidade Eduardo Mondlane, Maputo, Mozambique.
| | - Deus S Ishengoma
- National Institute for Medical Research (NIMR), Dar es Salaam, Tanzania; Faculty of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia; Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
| | - Joshua L Proctor
- Institute for Disease Modeling in Global Health, Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - Robert Verity
- MRC Centre for Global Infectious Disease Analysis, Imperial College, London, UK
| |
Collapse
|
5
|
Wafula ST, Habermann T, Franke MA, May J, Puradiredja DI, Lorenz E, Brinkel J. What are the pathways between poverty and malaria in sub-Saharan Africa? A systematic review of mediation studies. Infect Dis Poverty 2023; 12:58. [PMID: 37291664 DOI: 10.1186/s40249-023-01110-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 05/29/2023] [Indexed: 06/10/2023] Open
Abstract
BACKGROUND Malaria remains a major burden in sub-Saharan Africa (SSA). While an association between poverty and malaria has been demonstrated, a clearer understanding of explicit mechanisms through which socioeconomic position (SEP) influences malaria risk is needed to guide the design of more comprehensive interventions for malaria risk mitigation. This systematic review provides an overview of the current evidence on the mediators of socioeconomic disparities in malaria in SSA. METHODS We searched PubMed and Web of Science for randomised controlled trials, cohort, case-control and cross-sectional studies published in English between January 1, 2000 to May 31, 2022. Further studies were identified following reviews of reference lists of the studies included. We included studies that either (1) conducted a formal mediation analysis of risk factors on the causal pathway between SEP and malaria infections or (2) adjusted for these potential mediators as confounders on the association between SEP and malaria using standard regression models. At least two independent reviewers appraised the studies, conducted data extraction, and assessed risk of bias. A systematic overview is presented for the included studies. RESULTS We identified 41 articles from 20 countries in SSA for inclusion in the final review. Of these, 30 studies used cross-sectional design, and 26 found socioeconomic inequalities in malaria risk. Three formal mediation analyses showed limited evidence of mediation of food security, housing quality, and previous antimalarial use. Housing, education, insecticide-treated nets, and nutrition were highlighted in the remaining studies as being protective against malaria independent of SEP, suggesting potential for mediation. However, methodological limitations included the use of cross-sectional data, insufficient confounder adjustment, heterogeneity in measuring both SEP and malaria, and generally low or moderate-quality studies. No studies considered exposure mediator interactions or considered identifiability assumptions. CONCLUSIONS Few studies have conducted formal mediation analyses to elucidate pathways between SEP and malaria. Findings indicate that food security and housing could be more feasible (structural) intervention targets. Further research using well-designed longitudinal studies and improved analysis would illuminate the current sparse evidence into the pathways between SEP and malaria and adduce evidence for more potential targets for effective intervention.
Collapse
Affiliation(s)
- Solomon T Wafula
- Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
- Department of Disease Control and Environmental Health, School of Public Health, Makerere University, Kampala, Uganda.
| | - Theresa Habermann
- Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Mara Anna Franke
- Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- Charité Global Health, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Jürgen May
- Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection Research (DZIF), Partner Site Hamburg-Borstel-Lubeck-Riems, Hamburg, Germany
- Department of Tropical Medicine, University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Dewi Ismajani Puradiredja
- Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Eva Lorenz
- Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection Research (DZIF), Partner Site Hamburg-Borstel-Lubeck-Riems, Hamburg, Germany
- Institute of Medical Biostatistics, Epidemiology and Informatics, University Centre of the Johannes Gutenberg University, Mainz, Germany
| | - Johanna Brinkel
- Department of Infectious Disease Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
- German Center for Infection Research (DZIF), Partner Site Hamburg-Borstel-Lubeck-Riems, Hamburg, Germany
| |
Collapse
|
6
|
Gowelo S, Meijer P, Tizifa T, Malenga T, Mburu MM, Kabaghe AN, Terlouw DJ, van Vugt M, Phiri KS, Mzilahowa T, Koenraadt CJM, van den Berg H, Manda-Taylor L, McCann RS, Takken W. Community Participation in Habitat Management and Larviciding for the Control of Malaria Vectors in Southern Malawi. Am J Trop Med Hyg 2023; 108:51-60. [PMID: 36410320 PMCID: PMC9833073 DOI: 10.4269/ajtmh.21-1127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 08/23/2022] [Indexed: 11/23/2022] Open
Abstract
Larval source management (LSM) could reduce malaria transmission when executed alongside core vector control strategies. Involving communities in LSM could increase intervention coverage, reduce operational costs, and promote sustainability via community buy-in. We assessed the effectiveness of community-led LSM to reduce anopheline larval densities in 26 villages along the perimeter of Majete Wildlife Reserve in southern Malawi. The communities formed LSM committees which coordinated LSM activities in their villages following specialized training. Effectiveness of larviciding by LSM committees was assessed via pre- and post-spray larval sampling. The effect of community-led LSM on anopheline larval densities in intervention villages was assessed via comparisons with densities in non-LSM villages over a period of 14 months. Surveys involving 502 respondents were undertaken in intervention villages to explore community motivation and participation, and factors influencing these outcomes. Larviciding by LSM committees reduced anopheline larval densities in post-spray sampling compared with pre-spray sampling (P < 0.0001). No differences were observed between anopheline larval densities during pre-spray sampling in LSM villages and those in non-LSM villages (P = 0.282). Knowledge about vector biology and control, and someone's role in LSM motivated community participation in the vector control program. Despite reducing anopheline larval densities in LSM villages, the impact of the community-led LSM could not be detected in our study setting because of low mosquito densities after scale-up of core malaria control interventions. Still, the contributions of the intervention in increasing a community's knowledge of malaria, its risk factors, and its control methods highlight potential benefits of the approach.
Collapse
Affiliation(s)
- Steven Gowelo
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,MAC Communicable Diseases Action Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Paola Meijer
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Tinashe Tizifa
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Tumaini Malenga
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,African Institute for Development Policy, Lilongwe, Malawi
| | - Monicah M Mburu
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,Macha Research Trust, Choma, Zambia
| | - Alinune N Kabaghe
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Dianne J Terlouw
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Michèle van Vugt
- Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Kamija S Phiri
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Themba Mzilahowa
- MAC Communicable Diseases Action Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | | | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Lucinda Manda-Taylor
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Robert S McCann
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi.,Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| |
Collapse
|
7
|
Ediriweera DS, de Silva T, Kasturiratne A, de Silva HJ, Diggle P. Geographically regulated designs of incidence surveys can match the precision of classical survey designs whilst requiring smaller sample sizes: the case of snakebite envenoming in Sri Lanka. BMJ Glob Health 2022; 7:bmjgh-2022-009500. [PMID: 36220306 PMCID: PMC9557310 DOI: 10.1136/bmjgh-2022-009500] [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: 05/02/2022] [Accepted: 09/24/2022] [Indexed: 11/16/2022] Open
Abstract
Background Snakebite envenoming is a neglected tropical disease. Data from the worst affected countries are limited because conducting epidemiological surveys is challenging. We assessed the utility of inhibitory geostatistical design with close pairs (ICP) to estimate snakebite envenoming incidence. Methods The National Snakebite Survey (NSS) in Sri Lanka adopted a multistage cluster sampling design, based on population distribution, targeting 1% of the country’s population. Using a simulation-based study, we assessed predictive efficiency of ICP against a classical survey design at different fractions of the original sample size of the NSS. We also assessed travel distance, time taken to complete the survey, and sensitivity and specificity for detecting high-risk areas for snake envenoming, when using these methods. Results A classical survey design with 33% of the original NSS sample size was able to yield a similar predictive efficiency. ICP yielded the same at 25% of the NSS sample size, a 25% reduction in sample size compared with a classical survey design. ICP showed >80% sensitivity and specificity for detecting high-risk areas of envenoming when the sampling fraction was >20%. When ICP was adopted with 25% of the original NSS sample size, travel distance was reduced by >40% and time to conduct the survey was reduced by >75%. Conclusions This study showed that snakebite envenoming incidence can be estimated by adopting an ICP design with similar precision at a lower sample size than a classical design. This would substantially save resources and time taken to conduct epidemiological surveys and may be suited for low-resource settings.
Collapse
Affiliation(s)
| | - Tiloka de Silva
- Department of Decision Sciences, Faculty of Business, University of Moratuwa, Moratuwa, Sri Lanka
| | | | | | - Peter Diggle
- Centre for Health Informatics, Computing and Statistics, Lancaster University, Lancaster, UK
| |
Collapse
|
8
|
Tizifa TA, Gowelo S, Kabaghe AN, McCann RS, Malenga T, Nkhata RM, Kadama A, Chapeta Y, Takken W, Phiri KS, van Vugt M, van den Berg H, Manda-Taylor L. Community-based house improvement for malaria control in southern Malawi: Stakeholder perceptions, experiences, and acceptability. PLOS GLOBAL PUBLIC HEALTH 2022; 2:e0000627. [PMID: 36962454 PMCID: PMC10021647 DOI: 10.1371/journal.pgph.0000627] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 05/23/2022] [Indexed: 11/18/2022]
Abstract
House improvement (HI) refers to the full screening or closing of openings such as windows, doors, and eaves, as well as the installation of ceilings, to reduce mosquito-human contact indoors. HI is a viable supplementary intervention that reduces malaria transmission further than the existing strategies alone. In Malawi, HI has not been widely implemented and evaluated for malaria control. Concerns about lack of local evidence, durability in different epidemiological and cultural settings, and the cost of large-scale implementation are among the reasons the strategy is not utilised in many low-income countries. This study assessed community perceptions, experiences, and acceptability of community-led HI in Chikwawa district, southern Malawi. This was a qualitative study where separate focus group discussions were conducted with members from the general community (n = 3); health animators (n = 3); and HI committee members (n = 3). In-depth interviews were conducted with community members (n = 20), and key-informant interviews were conducted with health surveillance assistants and chiefs (n = 23). All interviews were transcribed and coded before performing a thematic content analysis to identify the main themes. Coded data were analysed using Nvivo 12 Plus software. Study participants had a thorough understanding of HI. Participants expressed satisfaction with HI, and they reported enabling factors to HI acceptability, such as the reduction in malaria cases in their villages and the safety and effectiveness of HI use. Participants also reported barriers to effective HI implementation, such as the unavailability and inaccessibility of some HI materials, as well as excessive heat and darkness in HI houses compared to non-HI houses. Participants indicated that they were willing to sustain the intervention but expressed the need for strategies to address barriers to ensure the effectiveness of HI. Our results showed the high knowledge and acceptability of HI by participants in the study area. Intensive and continued health education and community engagement on the significance of HI could help overcome the barriers and improve the acceptability and sustainability of the intervention.
Collapse
Affiliation(s)
- Tinashe A. Tizifa
- Division of Internal Medicine, Department of Infectious Diseases, Center for Tropical Medicine and Travel Medicine, University of Amsterdam, Amsterdam University Medical Center, Location Academic Medical Center, Amsterdam, The Netherlands
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Steven Gowelo
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Alinune N. Kabaghe
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Robert S. McCann
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- Centre for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Tumaini Malenga
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- African Institute for Development Policy, Lilongwe, Malawi
| | - Richard M. Nkhata
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Asante Kadama
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Yankho Chapeta
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- Biological Sciences Department, Mzuzu University, Mzuzu, Malawi
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Kamija S. Phiri
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Michele van Vugt
- Division of Internal Medicine, Department of Infectious Diseases, Center for Tropical Medicine and Travel Medicine, University of Amsterdam, Amsterdam University Medical Center, Location Academic Medical Center, Amsterdam, The Netherlands
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Lucinda Manda-Taylor
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| |
Collapse
|
9
|
Sedda L, McCann RS, Kabaghe AN, Gowelo S, Mburu MM, Tizifa TA, Chipeta MG, van den Berg H, Takken W, van Vugt M, Phiri KS, Cain R, Tangena JAA, Jones CM. Hotspots and super-spreaders: Modelling fine-scale malaria parasite transmission using mosquito flight behaviour. PLoS Pathog 2022; 18:e1010622. [PMID: 35793345 PMCID: PMC9292116 DOI: 10.1371/journal.ppat.1010622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 07/18/2022] [Accepted: 05/27/2022] [Indexed: 11/19/2022] Open
Abstract
Malaria hotspots have been the focus of public health managers for several years due to the potential elimination gains that can be obtained from targeting them. The identification of hotspots must be accompanied by the description of the overall network of stable and unstable hotspots of malaria, especially in medium and low transmission settings where malaria elimination is targeted. Targeting hotspots with malaria control interventions has, so far, not produced expected benefits. In this work we have employed a mechanistic-stochastic algorithm to identify clusters of super-spreader houses and their related stable hotspots by accounting for mosquito flight capabilities and the spatial configuration of malaria infections at the house level. Our results show that the number of super-spreading houses and hotspots is dependent on the spatial configuration of the villages. In addition, super-spreaders are also associated to house characteristics such as livestock and family composition. We found that most of the transmission is associated with winds between 6pm and 10pm although later hours are also important. Mixed mosquito flight (downwind and upwind both with random components) were the most likely movements causing the spread of malaria in two out of the three study areas. Finally, our algorithm (named MALSWOTS) provided an estimate of the speed of malaria infection progression from house to house which was around 200-400 meters per day, a figure coherent with mark-release-recapture studies of Anopheles dispersion. Cross validation using an out-of-sample procedure showed accurate identification of hotspots. Our findings provide a significant contribution towards the identification and development of optimal tools for efficient and effective spatio-temporal targeted malaria interventions over potential hotspot areas.
Collapse
Affiliation(s)
- Luigi Sedda
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, United Kingdom
| | - Robert S. McCann
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alinune N. Kabaghe
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Steven Gowelo
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- MAC Communicable Diseases Action Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Monicah M. Mburu
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Tinashe A. Tizifa
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Center for Tropical Medicine and Travel Medicine, University of Amsterdam, The Netherlands
| | - Michael G. Chipeta
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Michèle van Vugt
- Center for Tropical Medicine and Travel Medicine, University of Amsterdam, The Netherlands
| | - Kamija S. Phiri
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Russell Cain
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, United Kingdom
| | - Julie-Anne A. Tangena
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Christopher M. Jones
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| |
Collapse
|
10
|
Case BKM, Young JG, Penados D, Monroy C, Hébert-Dufresne L, Stevens L. Spatial epidemiology and adaptive targeted sampling to manage the Chagas disease vector Triatoma dimidiata. PLoS Negl Trop Dis 2022; 16:e0010436. [PMID: 35653307 PMCID: PMC9162375 DOI: 10.1371/journal.pntd.0010436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/20/2022] [Indexed: 11/18/2022] Open
Abstract
Widespread application of insecticide remains the primary form of control for Chagas disease in Central America, despite only temporarily reducing domestic levels of the endemic vector Triatoma dimidiata and having little long-term impact. Recently, an approach emphasizing community feedback and housing improvements has been shown to yield lasting results. However, the additional resources and personnel required by such an intervention likely hinders its widespread adoption. One solution to this problem would be to target only a subset of houses in a community while still eliminating enough infestations to interrupt disease transfer. Here we develop a sequential sampling framework that adapts to information specific to a community as more houses are visited, thereby allowing us to efficiently find homes with domiciliary vectors while minimizing sampling bias. The method fits Bayesian geostatistical models to make spatially informed predictions, while gradually transitioning from prioritizing houses based on prediction uncertainty to targeting houses with a high risk of infestation. A key feature of the method is the use of a single exploration parameter, α, to control the rate of transition between these two design targets. In a simulation study using empirical data from five villages in southeastern Guatemala, we test our method using a range of values for α, and find it can consistently select fewer homes than random sampling, while still bringing the village infestation rate below a given threshold. We further find that when additional socioeconomic information is available, much larger savings are possible, but that meeting the target infestation rate is less consistent, particularly among the less exploratory strategies. Our results suggest new options for implementing long-term T. dimidiata control. Effective public health interventions for the control and elimination of neglected tropical diseases require an efficient use of resources while still causing long-term disease reduction at the community level. To use resources to best effect, areas most in need of control efforts must be identified. However, strategies for correctly identifying these areas are rarely known due to the complex environmental, biological, and cultural factors shaping disease spread. In turn, incorrect prioritization of control targets can cause the intervention to have no lasting effect. We address this tradeoff between efficiency and efficacy by adapting control priorities throughout an intervention, targeting areas of high uncertainty during the initial stages while shifting to areas of greatest risk at later stages. In the context of controlling Triatoma dimidiata, the primary vector of Chagas disease in several countries in Latin America, our methods provide a means of targeting only a subset of homes for insecticide and housing improvements, while still reducing a village’s overall infestation rate below the critical threshold.
Collapse
Affiliation(s)
- B. K. M. Case
- Vermont Complex Systems Center, University of Vermont, Burlington, Vermont, United States of America
- Department of Computer Science, University of Vermont, Burlington, Vermont, United States of America
- * E-mail:
| | - Jean-Gabriel Young
- Vermont Complex Systems Center, University of Vermont, Burlington, Vermont, United States of America
- Department of Mathematics & Statistics, University of Vermont, Burlington, Vermont, United States of America
| | - Daniel Penados
- Laboratorio de Entomología Aplicada y Parasitología, Universidad de San Carlos de Guatemala, Ciudad de Guatemala, Guatemala
| | - Carlota Monroy
- Laboratorio de Entomología Aplicada y Parasitología, Universidad de San Carlos de Guatemala, Ciudad de Guatemala, Guatemala
| | - Laurent Hébert-Dufresne
- Vermont Complex Systems Center, University of Vermont, Burlington, Vermont, United States of America
- Department of Computer Science, University of Vermont, Burlington, Vermont, United States of America
| | - Lori Stevens
- Department of Biology, University of Vermont, Burlington, Vermont, United States of America
| |
Collapse
|
11
|
Incidence of clinical malaria, acute respiratory illness, and diarrhoea in children in southern Malawi: a prospective cohort study. Malar J 2021; 20:473. [PMID: 34930300 PMCID: PMC8685799 DOI: 10.1186/s12936-021-04013-5] [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: 08/11/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
Background Malaria, acute respiratory infections (ARIs) and diarrhoea are the leading causes of morbidity and mortality among children under 5 years old. Estimates of the malaria incidence are available from a previous study conducted in southern Malawi in the absence of community-led malaria control strategies; however, the incidence of the other diseases is lacking, owing to understudying and competing disease priorities. Extensive malaria control measures through a community participation strategy were implemented in Chikwawa, southern Malawi from May 2016 to reduce parasite prevalence and incidence. This study assessed the incidence of clinical malaria, ARIs and acute diarrhoea among under-five children in a rural community involved in malaria control through community participation. Methods A prospective cohort study was conducted from September 2017 to May 2019 in Chikwawa district, southern Malawi. Children aged 6–48 months were recruited from a series of repeated cross-sectional household surveys. Recruited children were followed up two-monthly for 1 year to record details of any clinic visits to designated health facilities. Incidence of clinical malaria, ARIs and diarrhoea per child-years at risk was estimated, compared between age groups, area of residence and time. Results A total of 274 out of 281 children recruited children had complete results and contributed 235.7 child-years. Malaria incidence was 0.5 (95% CI (0.4, 0.5)) cases per child-years at risk, (0.04 in 6.0–11.9 month-olds, 0.5 in 12.0–23.9 month-olds, 0.6 in 24.0–59.9 month-olds). Incidences of ARIs and diarrhoea were 0.3 (95% CI (0.2, 0.3)), (0.1 in 6.0–11.9 month-olds, 0.4 in 12.0–23.9 month-olds, 0.3 in 24.0–59.9 month-olds), and 0.2 (95% CI (0.2, 0.3)), (0.1 in 6.0–11.9 month-olds, 0.3 in 12.0–23.9 month-olds, 0.2 in 24.0–59.9 month-olds) cases per child-years at risk, respectively. There were temporal variations of malaria and ARI incidence and an overall decrease over time. Conclusion In comparison to previous studies, there was a lower incidence of clinical malaria in Chikwawa. The incidence of ARIs and diarrhoea were also low and decreased over time. The results are promising because they highlight the importance of community participation and the integration of malaria prevention strategies in contributing to disease burden reduction. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-04013-5.
Collapse
|
12
|
Byrne I, Chan K, Manrique E, Lines J, Wolie RZ, Trujillano F, Garay GJ, Del Prado Cortez MN, Alatrista-Salas H, Sternberg E, Cook J, N'Guessan R, Koffi A, Ahoua Alou LP, Apollinaire N, Messenger LA, Kristan M, Carrasco-Escobar G, Fornace K. Technical Workflow Development for Integrating Drone Surveys and Entomological Sampling to Characterise Aquatic Larval Habitats of Anopheles funestus in Agricultural Landscapes in Côte d'Ivoire. JOURNAL OF ENVIRONMENTAL AND PUBLIC HEALTH 2021; 2021:3220244. [PMID: 34759971 PMCID: PMC8575637 DOI: 10.1155/2021/3220244] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/07/2021] [Indexed: 11/17/2022]
Abstract
Land-use practices such as agriculture can impact mosquito vector breeding ecology, resulting in changes in disease transmission. The typical breeding habitats of Africa's second most important malaria vector Anopheles funestus are large, semipermanent water bodies, which make them potential candidates for targeted larval source management. This is a technical workflow for the integration of drone surveys and mosquito larval sampling, designed for a case study aiming to characterise An. funestus breeding sites near two villages in an agricultural setting in Côte d'Ivoire. Using satellite remote sensing data, we developed an environmentally and spatially representative sampling frame and conducted paired mosquito larvae and drone mapping surveys from June to August 2021. To categorise the drone imagery, we also developed a land cover classification scheme with classes relative to An. funestus breeding ecology. We sampled 189 potential breeding habitats, of which 119 (63%) were positive for the Anopheles genus and nine (4.8%) were positive for An. funestus. We mapped 30.42 km2 of the region of interest including all water bodies which were sampled for larvae. These data can be used to inform targeted vector control efforts, although its generalisability over a large region is limited by the fine-scale nature of this study area. This paper develops protocols for integrating drone surveys and statistically rigorous entomological sampling, which can be adjusted to collect data on vector breeding habitats in other ecological contexts. Further research using data collected in this study can enable the development of deep-learning algorithms for identifying An. funestus breeding habitats across rural agricultural landscapes in Côte d'Ivoire and the analysis of risk factors for these sites.
Collapse
Affiliation(s)
- Isabel Byrne
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Kallista Chan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Edgar Manrique
- Health Innovation Laboratory, Institute of Tropical Medicine “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Peru
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jo Lines
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Rosine Z. Wolie
- Institut Pierre Richet, Bouaké, Côte d'Ivoire
- Laboratoire de génétique, Unité de Formation et de Recherche en Biosciences, Université Félix Houphouët Boigny, Abidjan, Côte d'Ivoire
| | | | | | | | | | - Eleanore Sternberg
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Jackie Cook
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Raphael N'Guessan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Institut Pierre Richet, Bouaké, Côte d'Ivoire
| | | | | | | | - Louisa A. Messenger
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Mojca Kristan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Gabriel Carrasco-Escobar
- Health Innovation Laboratory, Institute of Tropical Medicine “Alexander von Humboldt”, Universidad Peruana Cayetano Heredia, Lima, Peru
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
| | - Kimberly Fornace
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, UK
| |
Collapse
|
13
|
Amoah B, McCann RS, Kabaghe AN, Mburu M, Chipeta MG, Moraga P, Gowelo S, Tizifa T, van den Berg H, Mzilahowa T, Takken W, van Vugt M, Phiri KS, Diggle PJ, Terlouw DJ, Giorgi E. Identifying Plasmodium falciparum transmission patterns through parasite prevalence and entomological inoculation rate. eLife 2021; 10:65682. [PMID: 34672946 PMCID: PMC8530514 DOI: 10.7554/elife.65682] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 09/30/2021] [Indexed: 11/13/2022] Open
Abstract
Background Monitoring malaria transmission is a critical component of efforts to achieve targets for elimination and eradication. Two commonly monitored metrics of transmission intensity are parasite prevalence (PR) and the entomological inoculation rate (EIR). Comparing the spatial and temporal variations in the PR and EIR of a given geographical region and modelling the relationship between the two metrics may provide a fuller picture of the malaria epidemiology of the region to inform control activities. Methods Using geostatistical methods, we compare the spatial and temporal patterns of Plasmodium falciparum EIR and PR using data collected over 38 months in a rural area of Malawi. We then quantify the relationship between EIR and PR by using empirical and mechanistic statistical models. Results Hotspots identified through the EIR and PR partly overlapped during high transmission seasons but not during low transmission seasons. The estimated relationship showed a 1-month delayed effect of EIR on PR such that at lower levels of EIR, increases in EIR are associated with rapid rise in PR, whereas at higher levels of EIR, changes in EIR do not translate into notable changes in PR. Conclusions Our study emphasises the need for integrated malaria control strategies that combine vector and human host managements monitored by both entomological and parasitaemia indices. Funding This work was supported by Stichting Dioraphte grant number 13050800.
Collapse
Affiliation(s)
- Benjamin Amoah
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Robert S McCann
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands.,Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, United States
| | - Alinune N Kabaghe
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, Netherlands
| | - Monicah Mburu
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands.,Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Michael G Chipeta
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi.,Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Paula Moraga
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, United Kingdom.,Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Steven Gowelo
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands.,Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Tinashe Tizifa
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, Netherlands
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands
| | - Themba Mzilahowa
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands
| | - Michele van Vugt
- Academic Medical Centre, University of Amsterdam, Amsterdam, Netherlands
| | - Kamija S Phiri
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Peter J Diggle
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Dianne J Terlouw
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi.,Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Emanuele Giorgi
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| |
Collapse
|
14
|
Zhao C, Wang Y, Tiseo K, Pires J, Criscuolo NG, Van Boeckel TP. Geographically targeted surveillance of livestock could help prioritize intervention against antimicrobial resistance in China. NATURE FOOD 2021; 2:596-602. [PMID: 37118162 DOI: 10.1038/s43016-021-00320-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 06/15/2021] [Indexed: 04/30/2023]
Abstract
The rise of antimicrobial resistance (AMR) in animals is being fuelled by the widespread use of veterinary antimicrobials. China is the largest global consumer of veterinary antimicrobials, and improving AMR surveillance strategies in this region could help prioritize intervention and preserve antimicrobial efficacy. Here we mapped AMR rates in pigs, chickens and cattle in China using 446 surveys of event-based surveillance between 2000 and 2019 for foodborne bacteria, in combination with geospatial models to identify locations where conducting new surveys could have the highest benefits. Using maps of uncertainty, we show that eastern China currently has the highest AMR rates, and southwestern and northeastern China would benefit the most from additional surveillance efforts. Instead of distributing new surveys evenly across administrative divisions, using geographically targeted surveillance could reduce AMR prediction uncertainty by two-fold. In a context of competing disease control priorities, our findings present a feasible option for optimizing surveillance efforts-and slowing the spread of AMR.
Collapse
Affiliation(s)
- Cheng Zhao
- Institute for Environmental Decisions, ETH Zurich, Zurich, Switzerland
| | - Yu Wang
- Institute for Environmental Decisions, ETH Zurich, Zurich, Switzerland
| | - Katie Tiseo
- Institute for Environmental Decisions, ETH Zurich, Zurich, Switzerland
| | - João Pires
- Institute for Environmental Decisions, ETH Zurich, Zurich, Switzerland
| | | | - Thomas P Van Boeckel
- Institute for Environmental Decisions, ETH Zurich, Zurich, Switzerland.
- Center for Disease Dynamics, Economics & Policy, Washington DC, USA.
| |
Collapse
|
15
|
Johnson O, Fronterre C, Amoah B, Montresor A, Giorgi E, Midzi N, Mutsaka-Makuvaza MJ, Kargbo-Labor I, Hodges MH, Zhang Y, Okoyo C, Mwandawiro C, Minnery M, Diggle PJ. Model-Based Geostatistical Methods Enable Efficient Design and Analysis of Prevalence Surveys for Soil-Transmitted Helminth Infection and Other Neglected Tropical Diseases. Clin Infect Dis 2021; 72:S172-S179. [PMID: 33905476 PMCID: PMC8201574 DOI: 10.1093/cid/ciab192] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Maps of the geographical variation in prevalence play an important role in large-scale programs for the control of neglected tropical diseases. Precontrol mapping is needed to establish the appropriate control intervention in each area of the country in question. Mapping is also needed postintervention to measure the success of control efforts. In the absence of comprehensive disease registries, mapping efforts can be informed by 2 kinds of data: empirical estimates of local prevalence obtained by testing individuals from a sample of communities within the geographical region of interest, and digital images of environmental factors that are predictive of local prevalence. In this article, we focus on the design and analysis of impact surveys, that is, prevalence surveys that are conducted postintervention with the aim of informing decisions on what further intervention, if any, is needed to achieve elimination of the disease as a public health problem. We show that geospatial statistical methods enable prevalence surveys to be designed and analyzed as efficiently as possible so as to make best use of hard-won field data. We use 3 case studies based on data from soil-transmitted helminth impact surveys in Kenya, Sierra Leone, and Zimbabwe to compare the predictive performance of model-based geostatistics with methods described in current World Health Organization (WHO) guidelines. In all 3 cases, we find that model-based geostatistics substantially outperforms the current WHO guidelines, delivering improved precision for reduced field-sampling effort. We argue from experience that similar improvements will hold for prevalence mapping of other neglected tropical diseases.
Collapse
Affiliation(s)
- Olatunji Johnson
- Centre for Health Informatics, Computing, and Statistics, Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Claudio Fronterre
- Centre for Health Informatics, Computing, and Statistics, Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Benjamin Amoah
- Centre for Health Informatics, Computing, and Statistics, Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Antonio Montresor
- Department of Control of Neglected Tropical Diseases, World Health Organization , Geneva, Switzerland
| | - Emanuele Giorgi
- Centre for Health Informatics, Computing, and Statistics, Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Nicholas Midzi
- National Institute of Health Research, Ministry of Health and Child Care, Zimbabwe
| | | | - Ibrahim Kargbo-Labor
- Neglected Tropical Disease Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Mary H Hodges
- Helen Keller International, Regional Office for Africa, Dakar, Senegal
| | - Yaobi Zhang
- Helen Keller International, Regional Office for Africa, Dakar, Senegal
| | - Collins Okoyo
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya.,School of Mathematics, College of Biological and Physical Sciences, University of Nairobi, Nairobi, Kenya
| | - Charles Mwandawiro
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya
| | - Mark Minnery
- Deworm the World, Evidence Action, Washington, District of Columbia, USA
| | - Peter J Diggle
- Centre for Health Informatics, Computing, and Statistics, Lancaster Medical School, Lancaster University, Lancaster, United Kingdom.,Health Data Research UK, London, United Kingdom
| |
Collapse
|
16
|
Diggle PJ, Amoah B, Fronterre C, Giorgi E, Johnson O. Rethinking neglected tropical disease prevalence survey design and analysis: a geospatial paradigm. Trans R Soc Trop Med Hyg 2021; 115:208-210. [PMID: 33587142 PMCID: PMC7946792 DOI: 10.1093/trstmh/trab020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/03/2021] [Indexed: 11/14/2022] Open
Abstract
Current methods for the design and analysis of neglected tropical disease prevalence surveys largely rely on classical survey sampling ideas that treat prevalence data from different locations as an independent random sample from the probability distribution induced by a random sampling design. We set out an alternative, explicitly geospatial paradigm that can deliver much more precise estimates of the geospatial variation in prevalence over a country or region of interest. We describe the advantages of this approach under three headings: streamlining, whereby more precise results can be obtained with smaller sample sizes; integrating, whereby a joint analysis of data from two or more diseases can bring further gains in precision; and adapting, whereby the choice of future sampling location is informed by past data.
Collapse
Affiliation(s)
- Peter J Diggle
- Medical School, Lancaster University, Lancaster, LA1 4YF, UK.,Health Data Research, 215 Euston Road, London, NW1 2BE, UK
| | - Benjamin Amoah
- Medical School, Lancaster University, Lancaster, LA1 4YF, UK
| | | | - Emanuele Giorgi
- Medical School, Lancaster University, Lancaster, LA1 4YF, UK
| | | |
Collapse
|
17
|
Odhiambo JN, Kalinda C, Macharia PM, Snow RW, Sartorius B. Spatial and spatio-temporal methods for mapping malaria risk: a systematic review. BMJ Glob Health 2021; 5:bmjgh-2020-002919. [PMID: 33023880 PMCID: PMC7537142 DOI: 10.1136/bmjgh-2020-002919] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/23/2020] [Accepted: 08/24/2020] [Indexed: 12/21/2022] Open
Abstract
Background Approaches in malaria risk mapping continue to advance in scope with the advent of geostatistical techniques spanning both the spatial and temporal domains. A substantive review of the merits of the methods and covariates used to map malaria risk has not been undertaken. Therefore, this review aimed to systematically retrieve, summarise methods and examine covariates that have been used for mapping malaria risk in sub-Saharan Africa (SSA). Methods A systematic search of malaria risk mapping studies was conducted using PubMed, EBSCOhost, Web of Science and Scopus databases. The search was restricted to refereed studies published in English from January 1968 to April 2020. To ensure completeness, a manual search through the reference lists of selected studies was also undertaken. Two independent reviewers completed each of the review phases namely: identification of relevant studies based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, data extraction and methodological quality assessment using a validated scoring criterion. Results One hundred and seven studies met the inclusion criteria. The median quality score across studies was 12/16 (range: 7–16). Approximately half (44%) of the studies employed variable selection techniques prior to mapping with rainfall and temperature selected in over 50% of the studies. Malaria incidence (47%) and prevalence (35%) were the most commonly mapped outcomes, with Bayesian geostatistical models often (31%) the preferred approach to risk mapping. Additionally, 29% of the studies employed various spatial clustering methods to explore the geographical variation of malaria patterns, with Kulldorf scan statistic being the most common. Model validation was specified in 53 (50%) studies, with partitioning data into training and validation sets being the common approach. Conclusions Our review highlights the methodological diversity prominent in malaria risk mapping across SSA. To ensure reproducibility and quality science, best practices and transparent approaches should be adopted when selecting the statistical framework and covariates for malaria risk mapping. Findings underscore the need to periodically assess methods and covariates used in malaria risk mapping; to accommodate changes in data availability, data quality and innovation in statistical methodology.
Collapse
Affiliation(s)
| | - Chester Kalinda
- Discipline of Public Health Medicine, University of KwaZulu-Natal, Durban, South Africa.,Faculty of Agriculture and Natural Resources, University of Namibia, Windhoek, Namibia
| | - Peter M Macharia
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Robert W Snow
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Benn Sartorius
- Discipline of Public Health Medicine, University of KwaZulu-Natal, Durban, South Africa.,Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| |
Collapse
|
18
|
Apetoh E, Roquet F, Palstra F, Baxerres C, Le Hesran JY. Household sampling through geocoded points and satellite view: A step-by-step approach to implement a spatial sampling method for demographic and health surveys in areas without population sampling frame and with limited resource settings. Rev Epidemiol Sante Publique 2021; 69:173-182. [PMID: 34148761 DOI: 10.1016/j.respe.2021.04.140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 04/05/2021] [Accepted: 04/06/2021] [Indexed: 11/25/2022] Open
Abstract
INTRODUCTION Spatial sampling is increasingly used in health surveys as it provides a simple way to randomly select target populations on sites where reliable and complete data on the general population are not available. However, the previously implemented protocols have been poorly detailed, making replication difficult or even impossible. To our knowledge, ours is the first document describing step-by-step an efficient spatial sampling method for health surveys. Our objective is to facilitate the rapid acquisition of the technical skills and know-how necessary for its deployment. METHODS The spatial sampling design is based on the random generation of geocoded points in the study area. Afterwards, these points were projected on the satellite view of Google Earth Pro™ software and the identified buildings were selected for field visits. A detailed formula of the number of points required, considering non-responses, is proposed. Density of buildings was determined by drawing circles around points and by using a replacement strategy when interviewing was unachievable. The method was implemented for a cross-sectional study during the April-May 2016 period in Cotonou (Bénin). The accuracy of the collected data was assessed by comparing them to those of the Cotonou national census. RESULT This approach does not require prior displacement in the study area and only 1% of identified buildings with Google Earth Pro™ were no longer extant. Most of the measurements resulting from the general census were within the confidence intervals of those calculated with the sample data. Furthermore, the range of measurements resulting from the general census was similar to those calculated with the sample data. These include, for example, the proportion of the foreign population (unweighted 8.9%/weighted 9% versus 8.5% in census data), the proportion of adults over 17 years of age (56.7% versus 57% in census data), the proportion of households whose head is not educated (unweighted 21.9%/weighted 22.8% versus 21.1% in census data). CONCLUSION This article illustrates how an epidemiological field survey based on spatial sampling can be successfully implemented at low cost, quickly and with little technical and theoretical knowledge. While statistically similar to simple random sampling, this survey method greatly simplifies its implementation.
Collapse
Affiliation(s)
- E Apetoh
- Institut de recherche pour le développement/Development research institute, Unité mixte de recherche 216/Mixed research unit 216: Mères et enfants face aux infections tropicale/Mother and child face to tropical infection, Faculté de pharmacie Paris-Descartes, 4, avenue de l'observatoire, 75006 Paris, France; École doctorale Pierre Louis de santé publique/Pierre-Louis doctoral public health school, ED 393 Épidémiologie et Sciences de l'Information Biomédicale/Epidemiology and biomedical information sciences, Paris, France.
| | - F Roquet
- Hôpital européen Georges-Pompidou, AP-HP, 20, rue Leblanc, 75015 Paris, France; ECSTRRA, CRESS-Unité mixte de recherche 1153, Hôpital Saint-Louis, 1, avenue Claude Vellefaux, 75010, Paris, France.
| | - F Palstra
- Centre Norbert Elias EHESS-Campus Marseille La Vieille Charité, 2, rue de la Charité, 13002 Marseille, France.
| | - C Baxerres
- Institut de recherche pour le développement/Development research institute, Unité mixte de recherche 216/Mixed research unit 216: Mères et enfants face aux infections tropicale/Mother and child face to tropical infection, Faculté de pharmacie Paris-Descartes, 4, avenue de l'observatoire, 75006 Paris, France; Centre Norbert Elias EHESS-Campus Marseille La Vieille Charité, 2, rue de la Charité, 13002 Marseille, France.
| | - J-Y Le Hesran
- Institut de recherche pour le développement/Development research institute, Unité mixte de recherche 216/Mixed research unit 216: Mères et enfants face aux infections tropicale/Mother and child face to tropical infection, Faculté de pharmacie Paris-Descartes, 4, avenue de l'observatoire, 75006 Paris, France.
| |
Collapse
|
19
|
Phiri MD, McCann RS, Kabaghe AN, van den Berg H, Malenga T, Gowelo S, Tizifa T, Takken W, van Vugt M, Phiri KS, Terlouw DJ, Worrall E. Cost of community-led larval source management and house improvement for malaria control: a cost analysis within a cluster-randomized trial in a rural district in Malawi. Malar J 2021; 20:268. [PMID: 34120608 PMCID: PMC8200285 DOI: 10.1186/s12936-021-03800-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 06/03/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND House improvement (HI) to prevent mosquito house entry, and larval source management (LSM) targeting aquatic mosquito stages to prevent development into adult forms, are promising complementary interventions to current malaria vector control strategies. Lack of evidence on costs and cost-effectiveness of community-led implementation of HI and LSM has hindered wide-scale adoption. This study presents an incremental cost analysis of community-led implementation of HI and LSM, in a cluster-randomized, factorial design trial, in addition to standard national malaria control interventions in a rural area (25,000 people), in southern Malawi. METHODS In the trial, LSM comprised draining, filling, and Bacillus thuringiensis israelensis-based larviciding, while house improvement (henceforth HI) involved closing of eaves and gaps on walls, screening windows/ventilation spaces with wire mesh, and doorway modifications. Communities implemented all interventions. Costs were estimated retrospectively using the 'ingredients approach', combining 'bottom-up' and 'top-down approaches', from the societal perspective. To estimate the cost of independently implementing each intervention arm, resources shared between trial arms (e.g. overheads) were allocated to each consuming arm using proxies developed based on share of resource input quantities consumed. Incremental implementation costs (in 2017 US$) are presented for HI-only, LSM-only and HI + LSM arms. In sensitivity analyses, the effect of varying costs of important inputs on estimated costs was explored. RESULTS The total economic programme costs of community-led HI and LSM implementation was $626,152. Incremental economic implementation costs of HI, LSM and HI + LSM were estimated as $27.04, $25.06 and $33.44, per person per year, respectively. Project staff, transport and labour costs, but not larvicide or screening material, were the major cost drivers across all interventions. Costs were sensitive to changes in staff costs and population covered. CONCLUSIONS In the trial, the incremental economic costs of community-led HI and LSM implementation were high compared to previous house improvement and LSM studies. Several factors, including intervention design, year-round LSM implementation and low human population density could explain the high costs. The factorial trial design necessitated use of proxies to allocate costs shared between trial arms, which limits generalizability where different designs are used. Nevertheless, costs may inform planners of similar intervention packages where cost-effectiveness is known. Trial registration Not applicable. The original trial was registered with The Pan African Clinical Trials Registry on 3 March 2016, trial number PACTR201604001501493.
Collapse
Affiliation(s)
- Mphatso Dennis Phiri
- Malaria Epidemiology Group, Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi.
| | - Robert S McCann
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, USA
| | - Alinune Nathanael Kabaghe
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Tumaini Malenga
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Steven Gowelo
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Tinashe Tizifa
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Michèle van Vugt
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam-UMC, Location AMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Kamija S Phiri
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Dianne J Terlouw
- Malaria Epidemiology Group, Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, UK
| | - Eve Worrall
- Liverpool School of Tropical Medicine, Liverpool, UK
| |
Collapse
|
20
|
Okebe J, Dabira E, Jaiteh F, Mohammed N, Bradley J, Drammeh NF, Bah A, Masunaga Y, Achan J, Muela Ribera J, Yeung S, Balen J, Peeters Grietens K, D'Alessandro U. Reactive, self-administered malaria treatment against asymptomatic malaria infection: results of a cluster randomized controlled trial in The Gambia. Malar J 2021; 20:253. [PMID: 34098984 PMCID: PMC8186162 DOI: 10.1186/s12936-021-03761-8] [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: 02/08/2021] [Accepted: 05/11/2021] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Selectively targeting and treating malaria-infected individuals may further decrease parasite carriage in low-burden settings. Using a trans-disciplinary approach, a reactive treatment strategy to reduce Plasmodium falciparum prevalence in participating communities was co-developed and tested. METHODS This is a 2-arm, open-label, cluster-randomized trial involving villages in Central Gambia during the 2017 and 2018 malaria transmission season. Villages were randomized in a 1:1 ratio using a minimizing algorithm. In the intervention arm, trained village health workers delivered a full course of pre-packed dihydroartemisinin-piperaquine to all residents of compounds where clinical cases were reported while in the control arm, compound residents were screened for infection at the time of the index case reporting. All index cases were treated following national guidelines. The primary endpoint was malaria prevalence, determined by molecular methods, at the end of the intervention period. RESULTS The trial was carried out in 50 villages: 34 in 2017 and 16 additional villages in 2018. At the end of the 2018 transmission season, malaria prevalence was 0.8% (16/1924, range 0-4%) and 1.1% (20/1814, range 0-17%) in the intervention and control arms, respectively. The odds of malaria infection were 29% lower in the intervention than in the control arm after adjustment for age (OR 0.71, 95% CI 0.27-1.84, p = 0.48). Adherence to treatment was high, with 98% (964/979) of those treated completing the 3-day treatment. Over the course of the study, only 37 villages, 20 in the intervention and 17 in the control arm, reported at least one clinical case. The distribution of clinical cases by month in both transmission seasons was similar and the odds of new clinical malaria cases during the trial period did not vary between arms (OR 1.04, 95% CI 0.57-1.91, p = 0.893). All adverse events were classified as mild to moderate and resolved completely. CONCLUSION The systematic and timely administration of an anti-malarial treatment to residents of compounds with confirmed malaria cases did not significantly decrease malaria prevalence and incidence in communities where malaria prevalence was already low. Treatment coverage and adherence was very high. Results were strongly influenced by the lower-than-expected malaria prevalence, and by no clinical cases in villages with asymptomatic malaria-infected individuals. TRIAL REGISTRATION This study is registered with ClinicalTrials.gov, NCT02878200. Registered 25 August 2016. https://clinicaltrials.gov/ct2/show/NCT02878200 .
Collapse
Affiliation(s)
- Joseph Okebe
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Edgard Dabira
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Fatou Jaiteh
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Amsterdam Institute of Social Science Research, Amsterdam, The Netherlands
| | - Nuredin Mohammed
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Ndey-Fatou Drammeh
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Amadou Bah
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Yoriko Masunaga
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Amsterdam Institute of Social Science Research, Amsterdam, The Netherlands
| | - Jane Achan
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
- Malaria Consortium, Cambridge Heath, London, UK
| | | | - Shunmay Yeung
- Clinical Research Department, London School of Hygiene and Tropical Medicine, London, UK
| | - Julie Balen
- School of Health and Related Research, The University of Sheffield, Sheffield, UK
| | | | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia.
| |
Collapse
|
21
|
Tizifa TA, Nkhono W, Mtengula S, van Vugt M, Munn Z, Kabaghe AN. Leveraging phone-based mobile technology to improve data quality at health facilities in rural Malawi: a best practice project. Malar J 2021; 20:203. [PMID: 33906650 PMCID: PMC8077781 DOI: 10.1186/s12936-021-03742-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 04/19/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND To further reduce malaria burden, identification of areas with highest burden for targeted interventions needs to occur. Routine health information has the potential to indicate where and when clinical malaria occurs the most. Developing countries mostly use paper-based data systems however they are error-prone as they require manual aggregation, tallying and transferring of data. Piloting was done using electronic data capture (EDC) with a cheap and user friendly software in rural Malawian primary healthcare setting to improve the quality of health records. METHODS Audit and feedback tools from the Joanna Briggs Institute (Practical Application of Clinical Evidence System and Getting Research into Practice) were used in four primary healthcare facilities. Using this approach, the best available evidence for a malaria information system (MIS) was identified. Baseline audit of the existing MIS was conducted in the facilities based on available best practice for MIS; this included ensuring data consistency and completeness in MIS by sampling 25 random records of malaria positive cases. Implementation of an adapted evidence-based EDC system using tablets on an OpenDataKit platform was done. An end line audit following implementation was then conducted. Users had interviews on experiences and challenges concerning EDC at the beginning and end of the survey. RESULTS The existing MIS was paper-based, occupied huge storage space, had some data losses due to torn out papers and were illegible in some facilities. The existing MIS did not have documentation of necessary parameters, such as malaria deaths and treatment within 14 days. Training manuals and modules were absent. One health centre solely had data completeness and consistency at 100% of the malaria-positive sampled records. Data completeness and consistency rose to 100% with readily available records containing information on recent malaria treatment. Interview findings at the end of the survey showed that EDC was acceptable among users and they agreed that the tablets and the OpenDataKit were easy to use, improved productivity and quality of care. CONCLUSIONS Improvement of data quality and use in the Malawian rural facilities was achieved through the introduction of EDC using OpenDataKit. Health workers in the facilities showed satisfaction with the use of EDC.
Collapse
Affiliation(s)
- Tinashe A. Tizifa
- Division of Internal Medicine, Department of Infectious Diseases, Center for Tropical Medicine and Travel Medicine, University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Training and Research Unit of Excellence (TRUE), School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - William Nkhono
- Training and Research Unit of Excellence (TRUE), School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Spencer Mtengula
- Training and Research Unit of Excellence (TRUE), School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Michele van Vugt
- Division of Internal Medicine, Department of Infectious Diseases, Center for Tropical Medicine and Travel Medicine, University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Zachary Munn
- JBI, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia
| | - Alinune N. Kabaghe
- Training and Research Unit of Excellence (TRUE), School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| |
Collapse
|
22
|
Mayfield HJ, Sturrock H, Arnold BF, Andrade-Pacheco R, Kearns T, Graves P, Naseri T, Thomsen R, Gass K, Lau CL. Supporting elimination of lymphatic filariasis in Samoa by predicting locations of residual infection using machine learning and geostatistics. Sci Rep 2020; 10:20570. [PMID: 33239779 PMCID: PMC7689447 DOI: 10.1038/s41598-020-77519-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 11/11/2020] [Indexed: 11/26/2022] Open
Abstract
The global elimination of lymphatic filariasis (LF) is a major focus of the World Health Organization. One key challenge is locating residual infections that can perpetuate the transmission cycle. We show how a targeted sampling strategy using predictions from a geospatial model, combining random forests and geostatistics, can improve the sampling efficiency for identifying locations with high infection prevalence. Predictions were made based on the household locations of infected persons identified from previous surveys, and environmental variables relevant to mosquito density. Results show that targeting sampling using model predictions would have allowed 52% of infections to be identified by sampling just 17.7% of households. The odds ratio for identifying an infected individual in a household at a predicted high risk compared to a predicted low risk location was 10.2 (95% CI 4.2-22.8). This study provides evidence that a 'one size fits all' approach is unlikely to yield optimal results when making programmatic decisions based on model predictions. Instead, model assumptions and definitions should be tailored to each situation based on the objective of the surveillance program. When predictions are used in the context of the program objectives, they can result in a dramatic improvement in the efficiency of locating infected individuals.
Collapse
Affiliation(s)
- Helen J Mayfield
- Research School of Population Health, Australian National University, Canberra, Australia.
| | - Hugh Sturrock
- Global Health Group, University of California, San Francisco, San Francisco, USA
| | - Benjamin F Arnold
- Proctor Foundation, University of California, San Francisco, San Francisco, USA
| | | | - Therese Kearns
- Menzies School of Health Research, Charles Darwin University, Brisbane, Australia
| | - Patricia Graves
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD, Australia
| | | | | | - Katherine Gass
- Neglected Tropical Diseases Support Center, Task Force for Global Heath, Decatur, GA, USA
| | - Colleen L Lau
- Research School of Population Health, Australian National University, Canberra, Australia
| |
Collapse
|
23
|
Finding hotspots: development of an adaptive spatial sampling approach. Sci Rep 2020; 10:10939. [PMID: 32616757 PMCID: PMC7331748 DOI: 10.1038/s41598-020-67666-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/08/2020] [Indexed: 01/09/2023] Open
Abstract
The identification of disease hotspots is an increasingly important public health problem. While geospatial modeling offers an opportunity to predict the locations of hotspots using suitable environmental and climatological data, little attention has been paid to optimizing the design of surveys used to inform such models. Here we introduce an adaptive sampling scheme optimized to identify hotspot locations where prevalence exceeds a relevant threshold. Our approach incorporates ideas from Bayesian optimization theory to adaptively select sample batches. We present an experimental simulation study based on survey data of schistosomiasis and lymphatic filariasis across four countries. Results across all scenarios explored show that adaptive sampling produces superior results and suggest that similar performance to random sampling can be achieved with a fraction of the sample size.
Collapse
|
24
|
Gowelo S, McCann RS, Koenraadt CJM, Takken W, van den Berg H, Manda-Taylor L. Community factors affecting participation in larval source management for malaria control in Chikwawa District, Southern Malawi. Malar J 2020; 19:195. [PMID: 32487233 PMCID: PMC7265157 DOI: 10.1186/s12936-020-03268-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 05/23/2020] [Indexed: 11/12/2022] Open
Abstract
Background To further reduce malaria, larval source management (LSM) is proposed as a complementary strategy to the existing strategies. LSM has potential to control insecticide resistant, outdoor biting and outdoor resting vectors. Concerns about costs and operational feasibility of implementation of LSM at large scale are among the reasons the strategy is not utilized in many African countries. Involving communities in LSM could increase intervention coverage, reduce costs of implementation and improve sustainability of operations. Community acceptance and participation in community-led LSM depends on a number of factors. These factors were explored under the Majete Malaria Project in Chikwawa district, southern Malawi. Methods Separate focus group discussions (FGDs) were conducted with members from the general community (n = 3); health animators (HAs) (n = 3); and LSM committee members (n = 3). In-depth interviews (IDIs) were conducted with community members. Framework analysis was employed to determine the factors contributing to community acceptance and participation in the locally-driven intervention. Results Nine FGDs and 24 IDIs were held, involving 87 members of the community. Widespread knowledge of malaria as a health problem, its mode of transmission, mosquito larval habitats and mosquito control was recorded. High awareness of an association between creation of larval habitats and malaria transmission was reported. Perception of LSM as a tool for malaria control was high. The use of a microbial larvicide as a form of LSM was perceived as both safe and effective. However, actual participation in LSM by the different interviewee groups varied. Labour-intensiveness and time requirements of the LSM activities, lack of financial incentives, and concern about health risks when wading in water bodies contributed to lower participation. Conclusion Community involvement in LSM increased local awareness of malaria as a health problem, its risk factors and control strategies. However, community participation varied among the respondent groups, with labour and time demands of the activities, and lack of incentives, contributing to reduced participation. Innovative tools that can reduce the labour and time demands could improve community participation in the activities. Further studies are required to investigate the forms and modes of delivery of incentives in operational community-driven LSM interventions.
Collapse
Affiliation(s)
- Steven Gowelo
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands. .,Training and Research Unit of Excellence, School of Public Health, College of Medicine, Blantyre, Malawi.
| | - Robert S McCann
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands.,Training and Research Unit of Excellence, School of Public Health, College of Medicine, Blantyre, Malawi.,Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Lucinda Manda-Taylor
- Training and Research Unit of Excellence, School of Public Health, College of Medicine, Blantyre, Malawi.,Department of Health Systems and Policy, School of Public Health and Family Medicine, College of Medicine, Blantyre, Malawi
| |
Collapse
|
25
|
Wang Y, Moe CL, Dutta S, Wadhwa A, Kanungo S, Mairinger W, Zhao Y, Jiang Y, Teunis PF. Designing a typhoid environmental surveillance study: A simulation model for optimum sampling site allocation. Epidemics 2020; 31:100391. [PMID: 32339811 PMCID: PMC7262602 DOI: 10.1016/j.epidem.2020.100391] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 01/29/2020] [Accepted: 03/13/2020] [Indexed: 11/19/2022] Open
Abstract
Environmental surveillance can be used for monitoring enteric disease in a population by detecting pathogens, shed by infected people, in sewage. Detection of pathogens depends on many factors: infection rates and shedding in the population, pathogen fate in the sewerage network, and also sampling sites, sample size, and assay sensitivity. This complexity makes the design of sampling strategies challenging, which creates a need for mathematical modeling to guide decision making. In the present study, a model was developed to simulate pathogen shedding, pathogen transport and fate in the sewerage network, sewage sampling, and detection of the pathogen. The simulation study used Salmonella enterica serovar Typhi (S. Typhi) as the target pathogen and two wards in Kolkata, India as the study area. Five different sampling strategies were evaluated for their sensitivity of detecting S. Typhi, by sampling unit: sewage pumping station, shared toilet, adjacent multiple shared toilets (primary sampling unit), pumping station + shared toilets, pumping station + primary sampling units. Sampling strategies were studied in eight scenarios with different geographic clustering of risk, pathogen loss (decay, leakage), and sensitivity of detection assays. A novel adaptive sampling site allocation method was designed, that updates the locations of sampling sites based on their performance. We then demonstrated how the simulation model can be used to predict the performance of environmental surveillance and how it is improved by optimizing the allocation of sampling sites. The results are summarized as a decision tree to guide the sampling strategy based on disease incidence, geographic distribution of risk, pathogen loss, and the sensitivity of the detection assay. The adaptive sampling site allocation method consistently outperformed alternatives with fixed site locations in most scenarios. In some cases, the optimum allocation method increased the median sensitivity from 45% to 90% within 20 updates.
Collapse
Affiliation(s)
- Yuke Wang
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA.
| | - Christine L Moe
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Shanta Dutta
- National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Ashutosh Wadhwa
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Suman Kanungo
- National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Wolfgang Mairinger
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Yichuan Zhao
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA
| | - Yi Jiang
- Department of Mathematics and Statistics, Georgia State University, Atlanta, GA, USA
| | - Peter Fm Teunis
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| |
Collapse
|
26
|
The population randomization observation process (PROP) assessment method: using systematic habitation observations of street segments to establish household-level epidemiologic population samples. Int J Health Geogr 2019; 18:24. [PMID: 31703586 PMCID: PMC6842250 DOI: 10.1186/s12942-019-0190-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 10/25/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Identifying and intervening on health disparities requires representative community public health data. For cities with high vacancy and transient populations, traditional methods of population estimation for refining random samples are not feasible. The aim of this project was to develop a novel method for systematic observations to establish community epidemiologic samples. RESULTS We devised a four-step population randomization observation process for Flint, Michigan, USA: (1) Use recent total population data for community areas (i.e., neighborhoods) to establish the proportional sample size for each area, (2) Randomly select street segments of each community area, (3) Deploy raters to conduct observations about habitation for each randomly selected segment, and (4) Complete observations for second and third street segments, depending on vacancy levels. We implemented this systematic observation process on 400 randomly selected street segments. Of these, 130 (32.5%) required assessment of secondary segments due to high vacancy. Among the 130 primary segments, 28 (21.5%) required assessment of tertiary (or more) segments. For 71.5% of the 400 primary street segments, there was consensus among raters on whether the dwelling inhabited or uninhabited. CONCLUSION Houses observed with this method could have easily been considered uninhabited via other methods. This could cause residents of ambiguous dwellings (likely to be the most marginalized residents with highest levels of unmet health needs) to be underrepresented in the resultant sample.
Collapse
|
27
|
Plowright RK, Becker DJ, McCallum H, Manlove KR. Sampling to elucidate the dynamics of infections in reservoir hosts. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180336. [PMID: 31401966 PMCID: PMC6711310 DOI: 10.1098/rstb.2018.0336] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2019] [Indexed: 01/20/2023] Open
Abstract
The risk of zoonotic spillover from reservoir hosts, such as wildlife or domestic livestock, to people is shaped by the spatial and temporal distribution of infection in reservoir populations. Quantifying these distributions is a key challenge in epidemiology and disease ecology that requires researchers to make trade-offs between the extent and intensity of spatial versus temporal sampling. We discuss sampling methods that strengthen the reliability and validity of inferences about the dynamics of zoonotic pathogens in wildlife hosts. This article is part of the theme issue 'Dynamic and integrative approaches to understanding pathogen spillover'.
Collapse
Affiliation(s)
- Raina K. Plowright
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Daniel J. Becker
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
- Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Hamish McCallum
- Environmental Futures Research Institute, Griffith University, Brisbane, Queensland 4111, Australia
| | - Kezia R. Manlove
- Department of Wildland Resources and Ecology Center, Utah State University, Logan, UT 84321, USA
| |
Collapse
|
28
|
Stresman G, Bousema T, Cook J. Malaria Hotspots: Is There Epidemiological Evidence for Fine-Scale Spatial Targeting of Interventions? Trends Parasitol 2019; 35:822-834. [PMID: 31474558 DOI: 10.1016/j.pt.2019.07.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/29/2019] [Accepted: 07/29/2019] [Indexed: 12/20/2022]
Abstract
As data at progressively granular spatial scales become available, the temptation is to target interventions to areas with higher malaria transmission - so-called hotspots - with the aim of reducing transmission in the wider community. This paper reviews literature to determine if hotspots are an intrinsic feature of malaria epidemiology and whether current evidence supports hotspot-targeted interventions. Hotspots are a consistent feature of malaria transmission at all endemicities. The smallest spatial unit capable of supporting transmission is the household, where peri-domestic transmission occurs. Whilst the value of focusing interventions to high-burden areas is evident, there is currently limited evidence that local-scale hotspots fuel transmission. As boundaries are often uncertain, there is no conclusive evidence that hotspot-targeted interventions accelerate malaria elimination.
Collapse
Affiliation(s)
- Gillian Stresman
- Infection Biology Department, London School of Hygiene and Tropical Medicine, London, UK.
| | - Teun Bousema
- Radboud University Medical Centre, Department of Microbiology, HB Nijmegen, The Netherlands.
| | - Jackie Cook
- Medical Research Council (MRC) Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| |
Collapse
|
29
|
Kaunda-Khangamwa BN, van den Berg H, McCann RS, Kabaghe A, Takken W, Phiri K, van Vugt M, Manda-Taylor L. The role of health animators in malaria control: a qualitative study of the health animator (HA) approach within the Majete malaria project (MMP) in Chikwawa District, Malawi. BMC Health Serv Res 2019; 19:478. [PMID: 31299974 PMCID: PMC6624973 DOI: 10.1186/s12913-019-4320-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 07/02/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Malaria continues to place a high burden on communities due to challenges reaching intervention target levels in Chikwawa District, Malawi. The Hunger Project Malawi is using a health animator approach (HA) to address gaps in malaria control coverage. We explored the influence of community-based volunteers known as health animators (HAs) in malaria control. We assessed the impact of HAs on knowledge, attitudes, and practices towards malaria interventions. METHODS This paper draws on the qualitative data collected to explore the roles of communities, HAs and formal health workers attending and not attending malaria workshops for malaria control. Purposive sampling was used to select 78 respondents. We conducted 10 separate focus group discussions (FGDs)-(n = 6) with community members and (n = 4) key informants. Nine in-depth interviews (IDIs) were held with HAs and Health Surveillance Assistants (HSAs) in three focal areas near Majete Wildlife Reserve. Nvivo 11 was used for coding and analysis. We employed the framework analysis and social capital theory to determine how the intervention influenced health and social outcomes. RESULTS Using education, feedback sessions and advocacy in malaria workshop had mixed outcomes. There was a high awareness of community participation and comprehensive knowledge of the HA approach as key to malaria control. HAs were identified as playing a complementary role in malaria intervention. Community members' attitudes towards advocacy for better health services were poor. Attendance in malaria workshops was sporadic towards the final year of the intervention. Respondents mentioned positive attitudes and practices on net usage for prevention and prompt health-seeking behaviours. CONCLUSION The HA approach is a useful strategy for complementing malaria prevention strategies in rural communities and improving practices for health-seeking behaviour. Various factors influence HAs' motivation, retention, community engagement, and programme sustainability. However, little is known about how these factors interact to influence volunteers' motivation, community participation and sustainability over time. More research is needed to explore the acceptability of an HA approach and the impact on malaria control in other rural communities in Malawi.
Collapse
Affiliation(s)
- Blessings N. Kaunda-Khangamwa
- The School of Public Health and Family Medicine, University of Malawi, College of Medicine, Blantyre, Malawi
- The Malaria Alert Centre, University of Malawi, College of Medicine, Blantyre, Malawi
- The University of Witwatersrand, School of Public Health, Johannesburg, South Africa
| | - Henk van den Berg
- Amsterdam UMC, location Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Robert S. McCann
- Wageningen University and Research Centre, Wageningen, The Netherlands
- Training and Research Unit of Excellence, University of Malawi, College of Medicine, Blantyre, Malawi
| | - Alinune Kabaghe
- The School of Public Health and Family Medicine, University of Malawi, College of Medicine, Blantyre, Malawi
- Training and Research Unit of Excellence, University of Malawi, College of Medicine, Blantyre, Malawi
| | - Willem Takken
- Wageningen University and Research Centre, Wageningen, The Netherlands
| | - Kamija Phiri
- The School of Public Health and Family Medicine, University of Malawi, College of Medicine, Blantyre, Malawi
- Training and Research Unit of Excellence, University of Malawi, College of Medicine, Blantyre, Malawi
| | - Michele van Vugt
- Amsterdam UMC, location Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Lucinda Manda-Taylor
- The School of Public Health and Family Medicine, University of Malawi, College of Medicine, Blantyre, Malawi
- Training and Research Unit of Excellence, University of Malawi, College of Medicine, Blantyre, Malawi
| |
Collapse
|
30
|
Chipeta MG, Giorgi E, Mategula D, Macharia PM, Ligomba C, Munyenyembe A, Chirombo J, Gumbo A, Terlouw DJ, Snow RW, Kayange M. Geostatistical analysis of Malawi's changing malaria transmission from 2010 to 2017. Wellcome Open Res 2019; 4:57. [PMID: 31372502 PMCID: PMC6662685 DOI: 10.12688/wellcomeopenres.15193.2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2019] [Indexed: 12/21/2022] Open
Abstract
Background: The prevalence of malaria infection in time and space provides important information on the likely sub-national epidemiology of malaria burdens and how this has changed following intervention. Model-based geostatitics (MBG) allow national malaria control programmes to leverage multiple data sources to provide predictions of malaria prevalance by district over time. These methods are used to explore the possible changes in malaria prevalance in Malawi from 2010 to 2017. Methods: Plasmodium falciparum parasite prevalence ( PfPR) surveys undertaken in Malawi between 2000 and 2017 were assembled. A spatio-temporal geostatistical model was fitted to predict annual malaria risk for children aged 2-10 years ( PfPR 2-10) at 1×1 km spatial resolutions. Parameter estimation was carried out using the Monte Carlo maximum likelihood methods. Population-adjusted prevalence and populations at risk by district were calculated for 2010 and 2017 to inform malaria control program priority setting. Results: 2,237 surveys at 1,834 communities undertaken between 2000 and 2017 were identified, geo-coded and used within the MBG framework to predict district malaria prevalence properties for 2010 and 2017. Nationally, there was a 47.2% reduction in the mean modelled PfPR 2-10 from 29.4% (95% confidence interval (CI) 26.6 to 32.3%) in 2010 to 15.2% (95% CI 13.3 to 18.0%) in 2017. Declining prevalence was not equal across the country, 25 of 27 districts showed a substantial decline ranging from a 3.3% reduction to 79% reduction. By 2017, 16% of Malawi's population still lived in areas that support PfPR 2-10 ≥ 25%. Conclusions: Malawi has made substantial progress in reducing the prevalence of malaria over the last seven years. However, Malawi remains in meso-endemic malaria transmission risk. To sustain the gains made and continue reducing the transmission further, universal control interventions need to be maintained at a national level.
Collapse
Affiliation(s)
- Michael Give Chipeta
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - Emanuele Giorgi
- Lancaster Medical School, Lancaster University, Lancaster, LA1 4YW, UK
| | - Donnie Mategula
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - Peter M. Macharia
- Population Health Unit, Kenya Medical Research Institute - Wellcome Trust Research Programme, Nairobi, Kenya
| | - Chimwemwe Ligomba
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - Alinane Munyenyembe
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - James Chirombo
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - Austin Gumbo
- National Malaria Control Programme, Malawi Ministry of Health, Lilongwe, Malawi
| | - Dianne J. Terlouw
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Robert W. Snow
- Population Health Unit, Kenya Medical Research Institute - Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX1 2JD, UK
| | - Michael Kayange
- National Malaria Control Programme, Malawi Ministry of Health, Lilongwe, Malawi
| |
Collapse
|
31
|
Sedda L, Lucas ER, Djogbénou LS, Edi AVC, Egyir-Yawson A, Kabula BI, Midega J, Ochomo E, Weetman D, Donnelly MJ. Improved spatial ecological sampling using open data and standardization: an example from malaria mosquito surveillance. J R Soc Interface 2019; 16:20180941. [PMID: 30966952 PMCID: PMC6505554 DOI: 10.1098/rsif.2018.0941] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 03/19/2019] [Indexed: 01/05/2023] Open
Abstract
Vector-borne disease control relies on efficient vector surveillance, mostly carried out using traps whose number and locations are often determined by expert opinion rather than a rigorous quantitative sampling design. In this work we propose a framework for ecological sampling design which in its preliminary stages can take into account environmental conditions obtained from open data (i.e. remote sensing and meteorological stations) not necessarily designed for ecological analysis. These environmental data are used to delimit the area into ecologically homogeneous strata. By employing Bayesian statistics within a model-based sampling design, the traps are deployed among the strata using a mixture of random and grid locations which allows balancing predictions and model-fitting accuracies. Sample sizes and the effect of ecological strata on sample sizes are estimated from previous mosquito sampling campaigns open data. Notably, we found that a configuration of 30 locations with four households each (120 samples) will have a similar accuracy in the predictions of mosquito abundance as 200 random samples. In addition, we show that random sampling independently from ecological strata, produces biased estimates of the mosquito abundance. Finally, we propose standardizing reporting of sampling designs to allow transparency and repetition/re-use in subsequent sampling campaigns.
Collapse
Affiliation(s)
- Luigi Sedda
- Centre for Health Information, Computation and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Furness Building, Lancaster LA1 4YG, UK
| | - Eric R. Lucas
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Luc S. Djogbénou
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Institut Régional de Santé Publique/Université d'Abomey–Calavi, BP 384 Ouidah, Benin
| | - Ako V. C. Edi
- Centre Suisse de Recherches Scientifiques en Cote d'Ivoire, 01 BP 1303 Abidjan 01, Cote d'Ivoire
| | | | - Bilali I. Kabula
- National Institute for Medical Research (NIMR), Amani Centre, PO Box 81, Muheza, Tanzania
| | - Janet Midega
- Centre for Geographic Medicine Research, Kenya Medical Research Institute, PO Box 230, 80108 Kilifi, Kenya
| | - Eric Ochomo
- Centre for Global Health Research, Kenya Medical Research Institute, PO Box 1578 – 40100 Kisumu, Kenya
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Martin J. Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| |
Collapse
|
32
|
Chipeta MG, Giorgi E, Mategula D, Macharia PM, Ligomba C, Munyenyembe A, Chirombo J, Gumbo A, Terlouw DJ, Snow RW, Kayange M. Geostatistical analysis of Malawi's changing malaria transmission from 2010 to 2017. Wellcome Open Res 2019; 4:57. [PMID: 31372502 PMCID: PMC6662685 DOI: 10.12688/wellcomeopenres.15193.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2019] [Indexed: 10/14/2023] Open
Abstract
Background: The prevalence of malaria infection in time and space provides important information on the likely sub-national epidemiology of malaria burdens and how this has changed following intervention. Model-based geostatitics (MBG) allow national malaria control programmes to leverage multiple data sources to provide predictions of malaria prevalance by district over time. These methods are used to explore the possible changes in malaria prevalance in Malawi from 2010 to 2017. Methods: Plasmodium falciparum parasite prevalence ( PfPR) surveys undertaken in Malawi between 2000 and 2017 were assembled. A spatio-temporal geostatistical model was fitted to predict annual malaria risk for children aged 2-10 years ( PfPR 2-10) at 1×1 km spatial resolutions. Parameter estimation was carried out using the Monte Carlo maximum likelihood methods. Population-adjusted prevalence and populations at risk by district were calculated for 2010 and 2017 to inform malaria control program priority setting. Results: 2,237 surveys at 1,834 communities undertaken between 2000 and 2017 were identified, geo-coded and used within the MBG framework to predict district malaria prevalence properties for 2010 and 2017. Nationally, there was a 47.2% reduction in the mean modelled PfPR 2-10 from 29.4% (95% confidence interval (CI) 26.6 to 32.3%) in 2010 to 15.2% (95% CI 13.3 to 18.0%) in 2017. Declining prevalence was not equal across the country, 25 of 27 districts showed a significant decline ranging from a 3.3% reduction to 79% reduction. By 2017, 16% of Malawi's population still lived in areas that support PfPR 2-10 ≥ 25%. Conclusions: Malawi has made substantial progress in reducing the prevalence of malaria over the last seven years. However, Malawi remains in meso-endemic malaria transmission risk. To sustain the gains made and continue reducing the transmission further, universal control interventions need to be maintained at a national level.
Collapse
Affiliation(s)
- Michael Give Chipeta
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - Emanuele Giorgi
- Lancaster Medical School, Lancaster University, Lancaster, LA1 4YW, UK
| | - Donnie Mategula
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - Peter M. Macharia
- Population Health Unit, Kenya Medical Research Institute - Wellcome Trust Research Programme, Nairobi, Kenya
| | - Chimwemwe Ligomba
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - Alinane Munyenyembe
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - James Chirombo
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
| | - Austin Gumbo
- National Malaria Control Programme, Malawi Ministry of Health, Lilongwe, Malawi
| | - Dianne J. Terlouw
- Malaria Epidemiology Group, Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Robert W. Snow
- Population Health Unit, Kenya Medical Research Institute - Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX1 2JD, UK
| | - Michael Kayange
- National Malaria Control Programme, Malawi Ministry of Health, Lilongwe, Malawi
| |
Collapse
|
33
|
Geostatistical analysis and mapping of malaria risk in children under 5 using point-referenced prevalence data in Ghana. Malar J 2019; 18:67. [PMID: 30871551 PMCID: PMC6419518 DOI: 10.1186/s12936-019-2709-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 03/06/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria remains a major challenge in sub-Saharan Africa and Ghana is not an exception. Effective malaria transmission control requires evidence-based targeting and utilization of resources. Disease risk mapping provides an effective and efficient tool for monitoring transmission and control efforts. The aim of this study is to analyse and map malaria risk in children under 5 years old, with the ultimate goal of identifying areas where control efforts can be targeted. METHODS Data collected from the 2016 Ghana demographic and health survey was analyzed. Binomial logistic regression was applied to examine the determinants of malaria risk among children. Model-based geostatistical methods were applied to analyze, predict and map malaria prevalence. RESULTS There is a significant association of malaria prevalence with area of residence (rural/urban), age, indoor residual spray use, social economic status and mother's education level. Overall, parasitaemia prevalence among children under 5 years old for the year 2016 is low albeit characterized by "hotspots" in specific areas. CONCLUSION The risk maps indicate the spatial heterogeneity of malaria prevalence. The high resolution maps can serve as an effective tool in the identification of locations that require targeted interventions by programme implementers; this is key and relevant for reducing malaria burden in Ghana.
Collapse
|
34
|
van den Berg H, van Vugt M, Kabaghe AN, Nkalapa M, Kaotcha R, Truwah Z, Malenga T, Kadama A, Banda S, Tizifa T, Gowelo S, Mburu MM, Phiri KS, Takken W, McCann RS. Community-based malaria control in southern Malawi: a description of experimental interventions of community workshops, house improvement and larval source management. Malar J 2018; 17:266. [PMID: 30012147 PMCID: PMC6048888 DOI: 10.1186/s12936-018-2415-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 07/10/2018] [Indexed: 12/22/2022] Open
Abstract
Background Increased engagement of communities has been emphasized in global plans for malaria control and elimination. Three interventions to reinforce and complement national malaria control recommendations were developed and applied within the context of a broad-based development initiative, targeting a rural population surrounding a wildlife reserve. The interventions, which were part of a 2-year research trial, and assigned to the village level, were implemented through trained local volunteers, or ‘health animators’, who educated the community and facilitated collective action. Results Community workshops on malaria were designed to increase uptake of national recommendations; a manual was developed, and training of health animators conducted, with educational content and analytical tools for a series of fortnightly community workshops in annual cycles at village level. The roll-back malaria principle of diagnosis, treatment and use of long-lasting insecticidal nets was a central component of the workshops. Structural house improvement to reduce entry of malaria vectors consisted of targeted activities in selected villages to mobilize the community into voluntarily closing the eaves and screening the windows of their houses; the project provided wire mesh for screening. Corrective measures were introduced to respond to field challenges. Committees were established at village level to coordinate the house improvement activities. Larval source management (LSM) in selected villages consisted of two parts: one on removal of standing water bodies by the community at large; and one on larviciding with bacterial insecticide Bacillus thuringiensis israelensis by trained village committees. Community workshops on malaria were implemented as ‘core intervention’ in all villages. House improvement and LSM were implemented in addition to community workshops on malaria in selected villages. Conclusions Three novel interventions for community mobilization on malaria prevention and control were described. The interventions comprised local organizational structure, education and collective action, and incorporated elements of problem identification, planning and evaluation. These methods could be applicable to other countries and settings. Electronic supplementary material The online version of this article (10.1186/s12936-018-2415-1) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Henk van den Berg
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700AA, Wageningen, The Netherlands.
| | - Michèle van Vugt
- Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Alinune N Kabaghe
- Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,College of Medicine, University of Malawi, Blantyre, Malawi
| | | | | | | | | | - Asante Kadama
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Saidon Banda
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Tinashe Tizifa
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Steven Gowelo
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700AA, Wageningen, The Netherlands.,College of Medicine, University of Malawi, Blantyre, Malawi
| | - Monicah M Mburu
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700AA, Wageningen, The Netherlands.,College of Medicine, University of Malawi, Blantyre, Malawi
| | - Kamija S Phiri
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Willem Takken
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700AA, Wageningen, The Netherlands
| | - Robert S McCann
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700AA, Wageningen, The Netherlands.,College of Medicine, University of Malawi, Blantyre, Malawi
| |
Collapse
|
35
|
Giorgi E, Diggle PJ, Snow RW, Noor AM. Geostatistical Methods for Disease Mapping and Visualisation Using Data from Spatio-temporally Referenced Prevalence Surveys. Int Stat Rev 2018; 86:571-597. [PMID: 33184527 DOI: 10.1111/insr.12268] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper, we set out general principles and develop geostatistical methods for the analysis of data from spatio-temporally referenced prevalence surveys. Our objective is to provide a tutorial guide that can be used in order to identify parsimonious geostatistical models for prevalence mapping. A general variogram-based Monte Carlo procedure is proposed to check the validity of the modelling assumptions. We describe and contrast likelihood-based and Bayesian methods of inference, showing how to account for parameter uncertainty under each of the two paradigms. We also describe extensions of the standard model for disease prevalence that can be used when stationarity of the spatio-temporal covariance function is not supported by the data. We discuss how to define predictive targets and argue that exceedance probabilities provide one of the most effective ways to convey uncertainty in prevalence estimates. We describe statistical software for the visualisation of spatio-temporal predictive summaries of prevalence through interactive animations. Finally, we illustrate an application to historical malaria prevalence data from 1 334 surveys conducted in Senegal between 1905 and 2014.
Collapse
Affiliation(s)
- Emanuele Giorgi
- Lancaster Medical School, Lancaster University, Lancaster, UK
| | - Peter J Diggle
- Lancaster Medical School, Lancaster University, Lancaster, UK
| | - Robert W Snow
- Population and Health Theme, Kenya Medical Research Institute - Wellcome Trust Research Programme, Nairobi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Abdisalan M Noor
- Population and Health Theme, Kenya Medical Research Institute - Wellcome Trust Research Programme, Nairobi, Kenya
| |
Collapse
|
36
|
Kabaghe AN, Chipeta MG, McCann RS, Terlouw DJ, Tizifa T, Truwah Z, Phiri KS, van Vugt M. Access and adequate utilization of malaria control interventions in rural Malawi: a descriptive quantitative study. Malar J 2018; 17:104. [PMID: 29510701 PMCID: PMC5838945 DOI: 10.1186/s12936-018-2253-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 03/02/2018] [Indexed: 11/23/2022] Open
Abstract
Background Despite the availability of cost effective malaria control interventions, such as insecticide-treated bed nets (ITN), diagnosis and effective treatment of malaria, and intermittent preventive treatment during pregnancy (IPTp), the lack of equitable access and coverage affect utilization of these interventions in rural communities. Aggregated rates of access and utilization of malaria interventions in national surveys mask substantial variations in intervention coverage. Utilization of interventions and factors affecting utilization need investigation in rural communities. Methods One year of quantitative data collected from a rolling Malaria Indicator Survey (April 2015–April 2016) in Chikhwawa District, Malawi, before the ITN distribution campaign, were analysed. Univariate analyses were used to quantify rates of ITN usage, care-seeking for fever in children aged 6–59 months and women aged 15–49 years and IPTp uptake (for women aged 15–49 years with a recent delivery). Results were compared to national survey estimates; factors associated with these outcomes were determined using multivariate regression models. Results A total of 2046 participants were included from 1328 households; 56.6% were women aged 15–49 years and 43.4% were children aged 6–59 months. Reported ownership of at least one ITN per household and under-five children ITN use the previous night were 35.3 and 33.5% compared to 70.2 and 67.1%, respectively, in the national survey; ITN use was higher in high wealth quintile households than low quintile ones. For participants with recent fever, 37.6 and 19.5% sought care and sought care within 24 h, respectively. Care-seeking was lower for febrile women than febrile children [aOR, 95% CI 0.53 (0.35–0.81)]. Uptake of two and three or more doses of IPTp were 40.6 and 15.0%, respectively, among women with a pregnancy in the last 2 years. Conclusion To achieve effective malaria control, fine-scale or district-based surveillance should be used to identify and target communities requiring scaling up of interventions. Qualitative research and a participatory community approach should be used to address behavioural factors affecting how people make use of interventions.
Collapse
Affiliation(s)
- Alinune Nathanael Kabaghe
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands. .,School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi.
| | - Michael Give Chipeta
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi.,Lancaster Medical School, Lancaster University, Lancaster, LA1 4YG, UK.,Malawi-Liverpool Wellcome Trust Clinical Research Program, Queen Elizabeth Central Hospital, College of Medicine, Blantyre, Malawi
| | - Robert Sean McCann
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi.,Laboratory of Entomology, Wageningen University and Research Centre, 6708 PB, Wageningen, The Netherlands
| | - Dianne Jean Terlouw
- Malawi-Liverpool Wellcome Trust Clinical Research Program, Queen Elizabeth Central Hospital, College of Medicine, Blantyre, Malawi
| | - Tinashe Tizifa
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi
| | - Zinenani Truwah
- Management Sciences for Health-Malawi Program, EBC Building, Off Paul Kagame Road, Private Bag 398, Lilongwe 3, Malawi
| | - Kamija Samuel Phiri
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi
| | - Michèle van Vugt
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands.
| |
Collapse
|
37
|
Kabaghe AN, Chipeta MG, Gowelo S, Mburu M, Truwah Z, McCann RS, van Vugt M, Grobusch MP, Phiri KS. Fine-scale spatial and temporal variation of clinical malaria incidence and associated factors in children in rural Malawi: a longitudinal study. Parasit Vectors 2018; 11:129. [PMID: 29506570 PMCID: PMC5839004 DOI: 10.1186/s13071-018-2730-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 02/19/2018] [Indexed: 11/25/2022] Open
Abstract
Background Spatio-temporal variations in malaria burden are currently complex and costly to measure, but are important for decision-making. We measured the spatio-temporal variation of clinical malaria incidence at a fine scale in a cohort of children under five in an endemic area in rural Chikhwawa, Malawi, determined associated factors, and monitored adult mosquito abundance. Methods We followed-up 285 children aged 6–48 months with recorded geolocations, who were sampled in a rolling malaria indicator survey, for one year (2015–2016). Guardians were requested to take the children to a nearby health facility whenever ill, where health facility personnel were trained to record malaria test results and temperature on the child’s sick-visit card; artemisinin-based combination therapy was provided if indicated. The cards were collected and replaced 2-monthly. Adult mosquitoes were collected from 2-monthly household surveys using a Suna trap. The head/thorax of adult Anopheles females were tested for presence of Plasmodium DNA. Binomial logistic regression and geospatial modelling were performed to determine predictors of and to spatially predict clinical malaria incidence, respectively. Results Two hundred eighty two children, with complete results, and 267.8 child-years follow-up time were included in the analysis. The incidence rate of clinical malaria was 1.2 cases per child-year at risk; 57.1% of the children had at least one clinical malaria case during follow-up. Geographical groups of households where children experienced repeated malaria infections overlapped with high mosquito densities and high entomological inoculation rate locations. Conclusions Repeated malaria infections within household groups account for the majority of cases and signify uneven distribution of malaria risk within a small geographical area. Electronic supplementary material The online version of this article (10.1186/s13071-018-2730-y) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Alinune N Kabaghe
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, Netherlands. .,School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi.
| | - Michael G Chipeta
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi.,Lancaster University, Lancaster Medical School, Lancaster, LA1 4YG, UK.,Malawi-Liverpool Wellcome Trust, P O Box 30096, Blantyre 3, Malawi
| | - Steve Gowelo
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi.,Laboratory of Entomology, Wageningen University and Research, 6708 PB, Wageningen, Netherlands
| | - Monicah Mburu
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi.,Laboratory of Entomology, Wageningen University and Research, 6708 PB, Wageningen, Netherlands
| | - Zinenani Truwah
- Management Sciences for Health - Malawi Program, EBC Building, Off Paul Kagame Road, Private Bag 398, Lilongwe 3, Malawi
| | - Robert S McCann
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi.,Laboratory of Entomology, Wageningen University and Research, 6708 PB, Wageningen, Netherlands
| | - Michèle van Vugt
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, Netherlands
| | - Martin P Grobusch
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, Netherlands
| | - Kamija S Phiri
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre 3, Malawi
| |
Collapse
|
38
|
Clark SJ, Wakefield J, McCormick T, Ross M. Hyak mortality monitoring system: innovative sampling and estimation methods - proof of concept by simulation. Glob Health Epidemiol Genom 2018; 3:e3. [PMID: 29868228 PMCID: PMC5870438 DOI: 10.1017/gheg.2017.15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 10/13/2017] [Accepted: 10/16/2017] [Indexed: 01/21/2023] Open
Abstract
Traditionally health statistics are derived from civil and/or vital registration. Civil registration in low- to middle-income countries varies from partial coverage to essentially nothing at all. Consequently the state of the art for public health information in low- to middle-income countries is efforts to combine or triangulate data from different sources to produce a more complete picture across both time and space - data amalgamation. Data sources amenable to this approach include sample surveys, sample registration systems, health and demographic surveillance systems, administrative records, census records, health facility records and others. We propose a new statistical framework for gathering health and population data - Hyak - that leverages the benefits of sampling and longitudinal, prospective surveillance to create a cheap, accurate, sustainable monitoring platform. Hyak has three fundamental components: Data amalgamation: A sampling and surveillance component that organizes two or more data collection systems to work together: (1) data from HDSS with frequent, intense, linked, prospective follow-up and (2) data from sample surveys conducted in large areas surrounding the Health and Demographic Surveillance System (HDSS) sites using informed sampling so as to capture as many events as possible;Cause of death: Verbal autopsy to characterize the distribution of deaths by cause at the population level; andSocioeconomic status (SES): Measurement of SES in order to characterize poverty and wealth. We conduct a simulation study of the informed sampling component of Hyak based on the Agincourt HDSS site in South Africa. Compared with traditional cluster sampling, Hyak's informed sampling captures more deaths, and when combined with an estimation model that includes spatial smoothing, produces estimates of both mortality counts and mortality rates that have lower variance and small bias.
Collapse
Affiliation(s)
- S. J. Clark
- Department of Sociology, The Ohio State University, Columbus, Ohio, USA
- MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), Faculty of Health Sciences, University of the Witwatersrand, School of Public Health, Johannesburg, South Africa
- INDEPTH Network, Accra, Ghana
- ALPHA Network, London, UK
| | - J. Wakefield
- Department of Statistics, University of Washington Seattle, Washington, USA
- Department of Biostatistics, University of Washington, Seattle, Washington, USA
| | - T. McCormick
- Department of Statistics, University of Washington Seattle, Washington, USA
- Department of Sociology, University of Washington, Seattle, Washington, USA
| | - M. Ross
- Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| |
Collapse
|
39
|
McCann RS, van den Berg H, Diggle PJ, van Vugt M, Terlouw DJ, Phiri KS, Di Pasquale A, Maire N, Gowelo S, Mburu MM, Kabaghe AN, Mzilahowa T, Chipeta MG, Takken W. Assessment of the effect of larval source management and house improvement on malaria transmission when added to standard malaria control strategies in southern Malawi: study protocol for a cluster-randomised controlled trial. BMC Infect Dis 2017; 17:639. [PMID: 28938876 PMCID: PMC5610449 DOI: 10.1186/s12879-017-2749-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 09/19/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Due to outdoor and residual transmission and insecticide resistance, long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) will be insufficient as stand-alone malaria vector control interventions in many settings as programmes shift toward malaria elimination. Combining additional vector control interventions as part of an integrated strategy would potentially overcome these challenges. Larval source management (LSM) and structural house improvements (HI) are appealing as additional components of an integrated vector management plan because of their long histories of use, evidence on effectiveness in appropriate settings, and unique modes of action compared to LLINs and IRS. Implementation of LSM and HI through a community-based approach could provide a path for rolling-out these interventions sustainably and on a large scale. METHODS/DESIGN We will implement community-based LSM and HI, as additional interventions to the current national malaria control strategies, using a randomised block, 2 × 2 factorial, cluster-randomised design in rural, southern Malawi. These interventions will be continued for two years. The trial catchment area covers about 25,000 people living in 65 villages. Community participation is encouraged by training community volunteers as health animators, and supporting the organisation of village-level committees in collaboration with The Hunger Project, a non-governmental organisation. Household-level cross-sectional surveys, including parasitological and entomological sampling, will be conducted on a rolling, 2-monthly schedule to measure outcomes over two years (2016 to 2018). Coverage of LSM and HI will also be assessed throughout the trial area. DISCUSSION Combining LSM and/or HI together with the interventions currently implemented by the Malawi National Malaria Control Programme is anticipated to reduce malaria transmission below the level reached by current interventions alone. Implementation of LSM and HI through a community-based approach provides an opportunity for optimum adaptation to the local ecological and social setting, and enhances the potential for sustainability. TRIAL REGISTRATION Registered with The Pan African Clinical Trials Registry on 3 March 2016, trial number PACTR201604001501493.
Collapse
Affiliation(s)
- Robert S McCann
- Wageningen University and Research, Wageningen, The Netherlands. .,College of Medicine, University of Malawi, Blantyre, Malawi. .,Laboratory of Entomology, Wageningen University and Research, PO Box 16, 6700, AA, Wageningen, The Netherlands.
| | | | | | - Michèle van Vugt
- Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Dianne J Terlouw
- Liverpool School of Tropical Medicine, Liverpool, UK.,Malawi-Liverpool Wellcome Trust, Blantyre, Malawi
| | - Kamija S Phiri
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Aurelio Di Pasquale
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Nicolas Maire
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Steven Gowelo
- College of Medicine, University of Malawi, Blantyre, Malawi
| | - Monicah M Mburu
- Wageningen University and Research, Wageningen, The Netherlands.,College of Medicine, University of Malawi, Blantyre, Malawi
| | - Alinune N Kabaghe
- College of Medicine, University of Malawi, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Michael G Chipeta
- College of Medicine, University of Malawi, Blantyre, Malawi.,Lancaster University, Lancaster, UK.,Malawi-Liverpool Wellcome Trust, Blantyre, Malawi
| | - Willem Takken
- Wageningen University and Research, Wageningen, The Netherlands
| |
Collapse
|
40
|
Kabaghe AN, Chipeta MG, Terlouw DJ, McCann RS, van Vugt M, Grobusch MP, Takken W, Phiri KS. Short-Term Changes in Anemia and Malaria Parasite Prevalence in Children under 5 Years during One Year of Repeated Cross-Sectional Surveys in Rural Malawi. Am J Trop Med Hyg 2017; 97:1568-1575. [PMID: 28820717 PMCID: PMC5817775 DOI: 10.4269/ajtmh.17-0335] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
In stable transmission areas, malaria is the leading cause of anemia in children. Anemia in children is proposed as an added sensitive indicator for community changes in malaria prevalence. We report short-term temporal variations of malaria and anemia prevalence in rural Malawian children. Data from five repeated cross-sectional surveys conducted over 1 year in rural communities in Chikwawa District, Malawi, were analyzed. Different households were sampled per survey; all children, 6–59 months, in sampled household were tested for malaria parasitemia and hemoglobin levels using malaria rapid diagnostic tests (mRDT) and Hemocue 301, respectively. Malaria symptoms, recent treatment (2 weeks) for malaria, anthropometric measurements, and sociodemographic details were recorded. In total, 894 children were included from 1,377 households. The prevalences of mRDT positive and anemia (Hb < 11 g/dL) were 33.8% and 58.7%, respectively. Temporal trends in anemia and parasite prevalence varied differently. Overall, unadjusted and adjusted relative risks of anemia in mRDT-positive children were 1.31 (95% CI: 1.09–1.57) and 1.36 (1.13–1.63), respectively. Changes in anemia prevalence differed with short-term changes in malaria prevalence, although malaria is an important factor in anemia.
Collapse
Affiliation(s)
- Alinune N Kabaghe
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi.,Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Michael G Chipeta
- Malawi-Liverpool Wellcome Trust Clinical Research Program, Queen Elizabeth Central Hospital, College of Medicine, Blantyre, Malawi.,Lancaster University, Lancaster Medical School, Lancaster, United Kingdom.,School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Dianne J Terlouw
- Malawi-Liverpool Wellcome Trust Clinical Research Program, Queen Elizabeth Central Hospital, College of Medicine, Blantyre, Malawi.,School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi.,Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Robert S McCann
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi.,Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands
| | - Michèle van Vugt
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Martin P Grobusch
- Center of Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands
| | - Kamija S Phiri
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| |
Collapse
|