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Traoré N, Singhal T, Millogo O, Sié A, Utzinger J, Vounatsou P. Relative effects of climate factors and malaria control interventions on changes of parasitaemia risk in Burkina Faso from 2014 to 2017/2018. BMC Infect Dis 2024; 24:166. [PMID: 38326750 PMCID: PMC10848559 DOI: 10.1186/s12879-024-08981-2] [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: 06/16/2023] [Accepted: 01/03/2024] [Indexed: 02/09/2024] Open
Abstract
BACKGROUND In Burkina Faso, the prevalence of malaria has decreased over the past two decades, following the scale-up of control interventions. The successful development of malaria parasites depends on several climatic factors. Intervention gains may be reversed by changes in climatic factors. In this study, we investigated the role of malaria control interventions and climatic factors in influencing changes in the risk of malaria parasitaemia. METHODS Bayesian logistic geostatistical models were fitted on Malaria Indicator Survey data from Burkina Faso obtained in 2014 and 2017/2018 to estimate the effects of malaria control interventions and climatic factors on the temporal changes of malaria parasite prevalence. Additionally, intervention effects were assessed at regional level, using a spatially varying coefficients model. RESULTS Temperature showed a statistically important negative association with the geographic distribution of parasitaemia prevalence in both surveys; however, the effects of insecticide-treated nets (ITNs) use was negative and statistically important only in 2017/2018. Overall, the estimated number of infected children under the age of 5 years decreased from 704,202 in 2014 to 290,189 in 2017/2018. The use of ITNs was related to the decline at national and regional level, but coverage with artemisinin-based combination therapy only at regional level. CONCLUSION Interventions contributed more than climatic factors to the observed change of parasitaemia risk in Burkina Faso during the period of 2014 to 2017/2018. Intervention effects varied in space. Longer time series analyses are warranted to determine the differential effect of a changing climate on malaria parasitaemia risk.
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Affiliation(s)
- Nafissatou Traoré
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, CH-4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-4001, Basel, Switzerland
- Nouna Health Research Centre, National Institute of Public Health, BP 02, Nouna, Burkina Faso
| | - Taru Singhal
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, CH-4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-4001, Basel, Switzerland
| | - Ourohiré Millogo
- Nouna Health Research Centre, National Institute of Public Health, BP 02, Nouna, Burkina Faso
- Institut de Recherche en Sciences de la Santé/Centre National de Recherche Scientifique et Technologique, 01 BP, 2779, Bobo-Dioulasso, Burkina Faso
| | - Ali Sié
- Nouna Health Research Centre, National Institute of Public Health, BP 02, Nouna, Burkina Faso
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, CH-4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, CH-4001, Basel, Switzerland
| | - Penelope Vounatsou
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, CH-4123, Allschwil, Switzerland.
- University of Basel, Petersplatz 1, CH-4001, Basel, Switzerland.
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Hadebe MT, Malgwi SA, Okpeku M. Revolutionizing Malaria Vector Control: The Importance of Accurate Species Identification through Enhanced Molecular Capacity. Microorganisms 2023; 12:82. [PMID: 38257909 PMCID: PMC10818655 DOI: 10.3390/microorganisms12010082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 12/08/2023] [Accepted: 12/20/2023] [Indexed: 01/24/2024] Open
Abstract
Many factors, such as the resistance to pesticides and a lack of knowledge of the morphology and molecular structure of malaria vectors, have made it more challenging to eradicate malaria in numerous malaria-endemic areas of the globe. The primary goal of this review is to discuss malaria vector control methods and the significance of identifying species in vector control initiatives. This was accomplished by reviewing methods of molecular identification of malaria vectors and genetic marker classification in relation to their use for species identification. Due to its specificity and consistency, molecular identification is preferred over morphological identification of malaria vectors. Enhanced molecular capacity for species identification will improve mosquito characterization, leading to accurate control strategies/treatment targeting specific mosquito species, and thus will contribute to malaria eradication. It is crucial for disease epidemiology and surveillance to accurately identify the Plasmodium spp. that are causing malaria in patients. The capacity for disease surveillance will be significantly increased by the development of more accurate, precise, automated, and high-throughput diagnostic techniques. In conclusion, although morphological identification is quick and achievable at a reduced cost, molecular identification is preferred for specificity and sensitivity. To achieve the targeted malaria elimination goal, proper identification of vectors using accurate techniques for effective control measures should be prioritized.
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Affiliation(s)
| | | | - Moses Okpeku
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Westville, Durban 4000, South Africa
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3
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Janko MM, Recalde-Coronel GC, Damasceno CP, Salmón-Mulanovich G, Barbieri AF, Lescano AG, Zaitchik BF, Pan WK. The impact of sustained malaria control in the Loreto region of Peru: a retrospective, observational, spatially-varying interrupted time series analysis of the PAMAFRO program. LANCET REGIONAL HEALTH. AMERICAS 2023; 20:100477. [PMID: 36970494 PMCID: PMC10036736 DOI: 10.1016/j.lana.2023.100477] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 10/23/2022] [Accepted: 03/07/2023] [Indexed: 03/18/2023]
Abstract
Background Although malaria control investments worldwide have resulted in dramatic declines in transmission since 2000, progress has stalled. In the Amazon, malaria resurgence has followed withdrawal of Global Fund support of the Project for Malaria Control in Andean Border Areas (PAMAFRO). We estimate intervention-specific and spatially-explicit effects of the PAMAFRO program on malaria incidence across the Loreto region of Peru, and consider the influence of the environmental risk factors in the presence of interventions. Methods We conducted a retrospective, observational, spatial interrupted time series analysis of malaria incidence rates among people reporting to health posts across Loreto, Peru between the first epidemiological week of January 2001 and the last epidemiological week of December 2016. Model inference is at the smallest administrative unit (district), where the weekly number of diagnosed cases of Plasmodium vivax and Plasmodium falciparum were determined by microscopy. Census data provided population at risk. We include as covariates weekly estimates of minimum temperature and cumulative precipitation in each district, as well as spatially- and temporally-lagged malaria incidence rates. Environmental data were derived from a hydrometeorological model designed for the Amazon. We used Bayesian spatiotemporal modeling techniques to estimate the impact of the PAMAFRO program, variability in environmental effects, and the role of climate anomalies on transmission after PAMAFRO withdrawal. Findings During the PAMAFRO program, incidence of P. vivax declined from 42.8 to 10.1 cases/1000 people/year. Incidence for P. falciparum declined from 14.3 to 2.5 cases/1000 people/year over this same period. The effects of PAMAFRO-supported interventions varied both by geography and species of malaria. Interventions were only effective in districts where interventions were also deployed in surrounding districts. Further, interventions diminished the effects of other prevailing demographic and environmental risk factors. Withdrawal of the program led to a resurgence in transmission. Increasing minimum temperatures and variability and intensity of rainfall events from 2011 onward and accompanying population displacements contributed to this resurgence. Interpretation Malaria control programs must consider the climate and environmental scope of interventions to maximize effectiveness. They must also ensure financial sustainability to maintain local progress and commitment to malaria prevention and elimination efforts, as well as to offset the effects of environmental change that increase transmission risk. Funding National Aeronautics and Space Administration, National Institutes of Health, Bill and Melinda Gates Foundation.
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Affiliation(s)
- Mark M. Janko
- Duke Global Health Institute, Duke University, Durham, NC, USA
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USA
| | - G. Cristina Recalde-Coronel
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA
- Facultad de Ingeniería Marítima y Ciencias del Mar, Escuela Superior Politécnica del Litoral, Guayaquil, Ecuador
| | | | | | | | - Andrés G. Lescano
- Clima, Latin American Center of Excellence for Climate Change and Health, and Emerge, Emerging Diseases and Climate Change Research Unit, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Benjamin F. Zaitchik
- Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD, USA
| | - William K. Pan
- Duke Global Health Institute, Duke University, Durham, NC, USA
- Nicholas School of the Environment, Duke University, Durham, NC, USA
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4
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Sarfo JO, Amoadu M, Kordorwu PY, Adams AK, Gyan TB, Osman AG, Asiedu I, Ansah EW. Malaria amongst children under five in sub-Saharan Africa: a scoping review of prevalence, risk factors and preventive interventions. Eur J Med Res 2023; 28:80. [PMID: 36800986 PMCID: PMC9936673 DOI: 10.1186/s40001-023-01046-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 02/06/2023] [Indexed: 02/19/2023] Open
Abstract
INTRODUCTION Africa has a higher burden of malaria-related cases and deaths globally. Children under five accounted for over two-thirds of all malaria deaths in sub-Saharan Africa (SSA). This scoping review aims to map evidence of the prevalence, contextual factors and health education interventions of malaria amongst children under 5 years (UN5) in SSA. METHOD Four main databases (PubMed, Central, Dimensions and JSTOR) produced 27,841 records of literature. Additional searches in Google, Google Scholar and institutional repositories produced 37 records. Finally, 255 full-text records were further screened, and 100 records were used for this review. RESULTS Low or no formal education, poverty or low income and rural areas are risk factors for malaria amongst UN5. Evidence on age and malnutrition as risk factors for malaria in UN5 is inconsistent and inconclusive. Furthermore, the poor housing system in SSA and the unavailability of electricity in rural areas and unclean water make UN5 more susceptible to malaria. Health education and promotion interventions have significantly reduced the malaria burden on UN5 in SSA. CONCLUSION Well-planned and resourced health education and promotion interventions that focus on prevention, testing and treatment of malaria could reduce malaria burden amongst UN5 in SSA.
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Affiliation(s)
- Jacob Owusu Sarfo
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
| | | | - Peace Yaa Kordorwu
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
| | - Abdul Karim Adams
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
| | | | - Abdul-Ganiyu Osman
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
| | - Immanuel Asiedu
- grid.413081.f0000 0001 2322 8567University of Cape Coast, Cape Coast, Ghana
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5
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Elmardi KA, Adam I, Malik EM, Kafy HT, Abdin MS, Kleinschmidt I, Kremers S. Impact of malaria control interventions on malaria infection and anaemia in areas with irrigated schemes: a cross-sectional population-based study in Sudan. BMC Infect Dis 2021; 21:1248. [PMID: 34906083 PMCID: PMC8670187 DOI: 10.1186/s12879-021-06929-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/01/2021] [Indexed: 11/29/2022] Open
Abstract
Background While the overall burden of malaria is still high, the global technical strategy for malaria advocates for two sets of interventions: vector control-based prevention and diagnosis and prompt effective treatment of malaria cases. This study aimed to assess the performance of malaria interventions on malaria infection and anaemia in irrigated areas in Sudan. Methods Based on the Sudan 2016 national malaria indicator survey, data for two states (Gezira and Sennar), characterized by large-irrigated schemes, were analysed. Four community-level malaria interventions were used as contextual variables: utilization of malaria diagnosis, utilization of Artemisinin-based combination therapy (ACT), utilization of long-lasting insecticidal nets (LLINs) and coverage with indoor residual spraying (IRS). Association between these interventions and two outcomes: malaria infection and anaemia, was assessed separately. Malaria infection was assessed in all age groups while anaemia was assessed in children under 5 years. Multilevel multiple logistic regression analysis were conducted. Results Among 4478 individuals involved in this study distributed over 47 clusters, the overall malaria infection rate was 3.0% and 56.5% of the children under 5 years (total = 322) were anaemic. Except for IRS coverage (69.6%), the average utilization of interventions was relatively low: 52.3% for utilization of diagnosis, 33.0% for utilization of ACTs and 18.6% for LLINs utilization. The multi-level multiple logistic regression model showed that only IRS coverage was associated with malaria infection (Odds ratio 0.83 per 10% coverage, 95%Confidence Interval (95%CI) 0.74–0.94, p = 0.003) indicating that a higher level of IRS coverage was associated with less malaria infection. Anaemia was not associated with any intervention (all p values larger than 0.1). Conclusions Malaria transmission in Gezira and Sennar areas is low. IRS, with insecticide to which vectors are susceptible, is an effective malaria control intervention in irrigated schemes. Community utilization of other interventions was not associated with malaria infection in this study. This may be due to the low utilization of these interventions. However, individual use of LLINs provide personal protection. This study failed to establish an association between anaemia and malaria control interventions in low transmission areas. The higher level of malaria infection in urban areas is a cause for concern.
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Affiliation(s)
- Khalid Abdelmutalab Elmardi
- Health Information, Monitoring and Evaluation and Evidence Department, Federal Ministry of Health, Khartoum, Sudan. .,Department of Health Promotion, Faculty of Health, Medicine and Life Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht, The Netherlands.
| | - Ishag Adam
- Department of Obstetrics and Gynecology, Unaizah College of Medicine and Medical Sciences, Qassim University, Unaizah, Saudi Arabia
| | | | - Hmooda Toto Kafy
- Directorate General of Primary Health Care, Federal Ministry of Health, Khartoum, Sudan
| | - Mogahid Sheikheldien Abdin
- Health Information, Monitoring and Evaluation and Evidence Department, Federal Ministry of Health, Khartoum, Sudan
| | - Immo Kleinschmidt
- MRC International Statistics and Epidemiology Group, Departments of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK.,Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Southern African Development Community Malaria Elimination Eight Secretariat, Windhoek, Namibia
| | - Stef Kremers
- Department of Health Promotion, Faculty of Health, Medicine and Life Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht, The Netherlands
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6
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Rural-urban dimensions of the perception of malaria severity and practice of malaria preventive measures: insight from the 2018 Nigeria Demographic and Health Survey. J Biosoc Sci 2021; 54:858-875. [PMID: 34533116 DOI: 10.1017/s0021932021000420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Morbidities and mortalities caused by malaria are still a serious issue in Nigeria, with the country accounting for 25% of malaria morbidities and 24% of malaria mortalities globally in 2018. Treated bed nets reduce the incidence of malaria, but not all Nigerians use them. This study aimed to examine the factors associated with treated bed net usage, including perceived severity of malaria, and the rural-urban differences in the relationship between socio-demographic factors and use of treated bed nets in Nigeria. The analytic sample size comprised 40,693 women aged 15-49 years. Poisson regression and bivariable and multivariable analyses were used to test the study hypothesis that women who agreed that malaria could potentially lead to death would be more likely to adopt malaria preventive measures, including treated bed net use. About 48% of the women slept under a treated mosquito net the night before the survey. Those who perceived that malaria could lead to death had a higher likelihood of using a treated bed net in the urban, rural and combined samples. However, in the multivariable model, the association between perceived malaria severity and use of a treated bed net was only significant for rural women (APR=0.964, 95% CI: 0.933, 0.996). The results unexpectedly suggest that rural Nigerian women who perceive malaria to be severe have a lower likelihood of using treated bed nets. Also, rural-urban variations in the relationship between the socio-demographic variables and use of treated bed nets were observed. Policies should consider the observed rural-urban dichotomy in the influence of perceived severity of malaria and other socio-demographic factors on women's use of treated bed nets in Nigeria.
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7
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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.
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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
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8
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Lee SA, Jarvis CI, Edmunds WJ, Economou T, Lowe R. Spatial connectivity in mosquito-borne disease models: a systematic review of methods and assumptions. J R Soc Interface 2021; 18:20210096. [PMID: 34034534 PMCID: PMC8150046 DOI: 10.1098/rsif.2021.0096] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 04/26/2021] [Indexed: 12/14/2022] Open
Abstract
Spatial connectivity plays an important role in mosquito-borne disease transmission. Connectivity can arise for many reasons, including shared environments, vector ecology and human movement. This systematic review synthesizes the spatial methods used to model mosquito-borne diseases, their spatial connectivity assumptions and the data used to inform spatial model components. We identified 248 papers eligible for inclusion. Most used statistical models (84.2%), although mechanistic are increasingly used. We identified 17 spatial models which used one of four methods (spatial covariates, local regression, random effects/fields and movement matrices). Over 80% of studies assumed that connectivity was distance-based despite this approach ignoring distant connections and potentially oversimplifying the process of transmission. Studies were more likely to assume connectivity was driven by human movement if the disease was transmitted by an Aedes mosquito. Connectivity arising from human movement was more commonly assumed in studies using a mechanistic model, likely influenced by a lack of statistical models able to account for these connections. Although models have been increasing in complexity, it is important to select the most appropriate, parsimonious model available based on the research question, disease transmission process, the spatial scale and availability of data, and the way spatial connectivity is assumed to occur.
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Affiliation(s)
- Sophie A. Lee
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Christopher I. Jarvis
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - W. John Edmunds
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | | | - Rachel Lowe
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
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Ferreira LZ, Blumenberg C, Utazi CE, Nilsen K, Hartwig FP, Tatem AJ, Barros AJD. Geospatial estimation of reproductive, maternal, newborn and child health indicators: a systematic review of methodological aspects of studies based on household surveys. Int J Health Geogr 2020; 19:41. [PMID: 33050935 PMCID: PMC7552506 DOI: 10.1186/s12942-020-00239-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/05/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Geospatial approaches are increasingly used to produce fine spatial scale estimates of reproductive, maternal, newborn and child health (RMNCH) indicators in low- and middle-income countries (LMICs). This study aims to describe important methodological aspects and specificities of geospatial approaches applied to RMNCH coverage and impact outcomes and enable non-specialist readers to critically evaluate and interpret these studies. METHODS Two independent searches were carried out using Medline, Web of Science, Scopus, SCIELO and LILACS electronic databases. Studies based on survey data using geospatial approaches on RMNCH in LMICs were considered eligible. Studies whose outcomes were not measures of occurrence were excluded. RESULTS We identified 82 studies focused on over 30 different RMNCH outcomes. Bayesian hierarchical models were the predominant modeling approach found in 62 studies. 5 × 5 km estimates were the most common resolution and the main source of information was Demographic and Health Surveys. Model validation was under reported, with the out-of-sample method being reported in only 56% of the studies and 13% of the studies did not present a single validation metric. Uncertainty assessment and reporting lacked standardization, and more than a quarter of the studies failed to report any uncertainty measure. CONCLUSIONS The field of geospatial estimation focused on RMNCH outcomes is clearly expanding. However, despite the adoption of a standardized conceptual modeling framework for generating finer spatial scale estimates, methodological aspects such as model validation and uncertainty demand further attention as they are both essential in assisting the reader to evaluate the estimates that are being presented.
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Affiliation(s)
- Leonardo Z Ferreira
- International Center for Equity in Health, Universidade Federal de Pelotas, Pelotas, Brazil.
- Post-Graduate Program in Epidemiology, Universidade Federal de Pelotas, Pelotas, Brazil.
| | - Cauane Blumenberg
- International Center for Equity in Health, Universidade Federal de Pelotas, Pelotas, Brazil
| | - C Edson Utazi
- WorldPop, Geography and Environmental Science, University of Southampton, Southampton, UK
| | - Kristine Nilsen
- WorldPop, Geography and Environmental Science, University of Southampton, Southampton, UK
| | - Fernando P Hartwig
- Post-Graduate Program in Epidemiology, Universidade Federal de Pelotas, Pelotas, Brazil
| | - Andrew J Tatem
- WorldPop, Geography and Environmental Science, University of Southampton, Southampton, UK
| | - Aluisio J D Barros
- International Center for Equity in Health, Universidade Federal de Pelotas, Pelotas, Brazil
- Post-Graduate Program in Epidemiology, Universidade Federal de Pelotas, Pelotas, Brazil
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10
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Abdur Rehman N, Salje H, Kraemer MUG, Subramanian L, Saif U, Chunara R. Quantifying the localized relationship between vector containment activities and dengue incidence in a real-world setting: A spatial and time series modelling analysis based on geo-located data from Pakistan. PLoS Negl Trop Dis 2020; 14:e0008273. [PMID: 32392225 PMCID: PMC7241855 DOI: 10.1371/journal.pntd.0008273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 05/21/2020] [Accepted: 04/07/2020] [Indexed: 11/19/2022] Open
Abstract
Increasing urbanization is having a profound effect on infectious disease risk, posing significant challenges for governments to allocate limited resources for their optimal control at a sub-city scale. With recent advances in data collection practices, empirical evidence about the efficacy of highly localized containment and intervention activities, which can lead to optimal deployment of resources, is possible. However, there are several challenges in analyzing data from such real-world observational settings. Using data on 3.9 million instances of seven dengue vector containment activities collected between 2012 and 2017, here we develop and assess two frameworks for understanding how the generation of new dengue cases changes in space and time with respect to application of different types of containment activities. Accounting for the non-random deployment of each containment activity in relation to dengue cases and other types of containment activities, as well as deployment of activities in different epidemiological contexts, results from both frameworks reinforce existing knowledge about the efficacy of containment activities aimed at the adult phase of the mosquito lifecycle. Results show a 10% (95% CI: 1-19%) and 20% reduction (95% CI: 4-34%) reduction in probability of a case occurring in 50 meters and 30 days of cases which had Indoor Residual Spraying (IRS) and fogging performed in the immediate vicinity, respectively, compared to cases of similar epidemiological context and which had no containment in their vicinity. Simultaneously, limitations due to the real-world nature of activity deployment are used to guide recommendations for future deployment of resources during outbreaks as well as data collection practices. Conclusions from this study will enable more robust and comprehensive analyses of localized containment activities in resource-scarce urban settings and lead to improved allocation of resources of government in an outbreak setting.
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Affiliation(s)
- Nabeel Abdur Rehman
- Computer Science and Engineering, Tandon School of Engineering, New York University, Brooklyn, New York, United States of America
| | | | | | | | - Umar Saif
- UNESCO Chair for ICTD, Lahore, Pakistan
| | - Rumi Chunara
- Computer Science and Engineering, Tandon School of Engineering, New York University, Brooklyn, New York, United States of America
- Department of Biostatistics, School of Global Public Health, New York University, New York, New York, United States of America
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11
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Manda S, Haushona N, Bergquist R. A Scoping Review of Spatial Analysis Approaches Using Health Survey Data in Sub-Saharan Africa. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E3070. [PMID: 32354095 PMCID: PMC7246597 DOI: 10.3390/ijerph17093070] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/01/2020] [Accepted: 04/03/2020] [Indexed: 01/03/2023]
Abstract
Spatial analysis has become an increasingly used analytic approach to describe and analyze spatial characteristics of disease burden, but the depth and coverage of its usage for health surveys data in Sub-Saharan Africa are not well known. The objective of this scoping review was to conduct an evaluation of studies using spatial statistics approaches for national health survey data in the SSA region. An organized literature search for studies related to spatial statistics and national health surveys was conducted through PMC, PubMed/Medline, Scopus, NLM Catalog, and Science Direct electronic databases. Of the 4,193 unique articles identified, 153 were included in the final review. Spatial smoothing and prediction methods were predominant (n = 108), followed by spatial description aggregation (n = 25), and spatial autocorrelation and clustering (n = 19). Bayesian statistics methods and lattice data modelling were predominant (n = 108). Most studies focused on malaria and fever (n = 47) followed by health services coverage (n = 38). Only fifteen studies employed nonstandard spatial analyses (e.g., spatial model assessment, joint spatial modelling, accounting for survey design). We recommend that for future spatial analysis using health survey data in the SSA region, there must be an improve recognition and awareness of the potential dangers of a naïve application of spatial statistical methods. We also recommend a wide range of applications using big health data and the future of data science for health systems to monitor and evaluate impacts that are not well understood at local levels.
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Affiliation(s)
- Samuel Manda
- Biostatistics Research Unit, South African Medical Research Council, Pretoria 0001, South Africa
- Department of Statistics, University of Pretoria, Pretoria 0002, South Africa
- School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Pietermaritzburg 3209, South Africa
| | - Ndamonaonghenda Haushona
- Biostatistics Research Unit, South African Medical Research Council, Pretoria 0001, South Africa
- Division of Epidemiology and Biostatistics, University of Stellenbosch, Cape Town 8000, South Africa
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Kim H, Miller FD, Hernandez A, Tanser F, Mogeni P, Cuadros DF. Spatiotemporal analysis of insecticide-treated net use for children under 5 in relation to socioeconomic gradients in Central and East Africa. Malar J 2020; 19:163. [PMID: 32321547 PMCID: PMC7178571 DOI: 10.1186/s12936-020-03236-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 04/15/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated net (ITN) use is the core intervention among the strategies against malaria in sub-Saharan Africa (SSA) and the percentage of ITN ownership has increased from 47% in 2010 to 72% in 2017 across countries in SSA. Regardless of this massive expansion of ITN distribution, considerable gap between ownership and use of ITNs has been reported. Using data from more than 100,000 households in Central and East Africa (CEA) countries, the main aim of this study was to identify barriers associated with low ITN use and conduct geospatial analyses to estimate numbers and locations of vulnerable children living in areas with high malaria and low ITN use. METHODS Main sources of data for this study were the Demographic and Health Surveys and Malaria Indicator Surveys conducted in 11 countries in CEA. Logistic regression models for each country were built to assess the association between ITN ownership or ITN use and several socioeconomic and demographic variables. A density map of children under 5 living in areas at high-risk of malaria and low ITN use was generated to estimate the number of children who are living in these high malaria burden areas. RESULTS Results obtained suggest that factors such as the number of members in the household, total number of children in the household, education and place of residence can be key factors linked to the use of ITN for protecting children against malaria in CEA. Results from the spatiotemporal analyses found that although total rates of ownership and use of ITNs across CEA have increased up to 70% and 48%, respectively, a large proportion of children under 5 (19,780,678; 23% of total number of children) still lives in high-risk malaria areas with low use of ITNs. CONCLUSION The results indicate that despite substantial progress in the distribution of ITNs in CEA, with about 70% of the households having an ITN, several socioeconomic factors have compromised the effectiveness of this control intervention against malaria, and only about 48% of the households protect their children under 5 with ITNs. Increasing the effective ITN use by targeting these factors and the areas where vulnerable children reside can be a core strategy meant to reducing malaria transmission.
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Affiliation(s)
- Hana Kim
- Department of Geography and Geographic Information Science, University of Cincinnati, Cincinnati, OH, 45221, USA.,Health Geography and Disease Modeling Laboratory, University of Cincinnati, Cincinnati, USA
| | - F DeWolfe Miller
- Department of Tropical Medicine and Medical Microbiology and Pharmacology, University of Hawaii, Honolulu, HI, USA
| | - Andres Hernandez
- Department of Geography and Geographic Information Science, University of Cincinnati, Cincinnati, OH, 45221, USA.,Health Geography and Disease Modeling Laboratory, University of Cincinnati, Cincinnati, USA
| | - Frank Tanser
- Research Department of Infection & Population Health, University College London, London, UK.,Africa Health Research Institute, Durban, Kwazulu-Natal, South Africa.,School of Nursing and Public Health, University of KwaZulu-Natal, Durban, Kwazulu-Natal, South Africa
| | - Polycarp Mogeni
- Africa Health Research Institute, Durban, Kwazulu-Natal, South Africa.,School of Nursing and Public Health, University of KwaZulu-Natal, Durban, Kwazulu-Natal, South Africa
| | - Diego F Cuadros
- Department of Geography and Geographic Information Science, University of Cincinnati, Cincinnati, OH, 45221, USA. .,Health Geography and Disease Modeling Laboratory, University of Cincinnati, Cincinnati, USA.
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Effect of Free Healthcare Policy for Children under Five Years Old on the Incidence of Reported Malaria Cases in Burkina Faso by Bayesian Modelling: "Not only the Ears but also the Head of the Hippopotamus". INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17020417. [PMID: 31936308 PMCID: PMC7014427 DOI: 10.3390/ijerph17020417] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 12/24/2019] [Accepted: 01/03/2020] [Indexed: 02/02/2023]
Abstract
Burkina Faso has recently implemented an additional strategy, the free healthcare policy, to further improve maternal and child health. This policy targets children under five who bear the brunt of the malaria scourge. The effects of the free-of-charge healthcare were previously assessed in women but not in children. The present study aims at filling this gap by assessing the effect of this policy in children under five with a focus on the induced spatial and temporal changes in malaria morbidity. We used a Bayesian spatiotemporal negative binomial model to investigate the space–time variation in malaria incidence in relation to the implementation of the policy. The analysis relied on malaria routine surveillance data extracted from the national health data repository and spanning the period from January 2013 to December 2018. The model was adjusted for meteorological and contextual confounders. We found that the number of presumed and confirmed malaria cases per 1000 children per month increased between 2013 and 2018. We further found that the implementation of the free healthcare policy was significantly associated with a two-fold increase in the number of tested and confirmed malaria cases compared with the period before the policy rollout. This effect was, however, heterogeneous across the health districts. We attributed the rise in malaria incidence following the policy rollout to an increased use of health services combined with an increased availability of rapid tests and a higher compliance to the “test and treat” policy. The observed heterogeneity in the policy effect was attributed to parallel control interventions, some of which were rolled out at different paces and scales. Our findings call for a sustained and reinforced effort to test all suspected cases so that, alongside an improved case treatment, the true picture of the malaria scourge in children under five emerges clearly (see the hippopotamus almost entirely).
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Philbert A, Lyantagaye SL, Nkwengulila G. Farmers' pesticide usage practices in the malaria endemic region of North-Western Tanzania: implications to the control of malaria vectors. BMC Public Health 2019; 19:1456. [PMID: 31694595 PMCID: PMC6833290 DOI: 10.1186/s12889-019-7767-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 10/11/2019] [Indexed: 11/21/2022] Open
Abstract
Background Pesticides remain the mainstay for the control of agricultural pests and disease vectors. However, their indiscriminate use in agriculture has led to development of resistance to both crop pests and disease vectors. This threatens to undermine the success gained through the implementation of chemical based vector control programs. We investigated the practices of farmers with regard to pesticide usage in the vegetable growing areas and their impact on susceptibility status of An. gambiae s.l. Methods A stratified multistage sampling technique using the administrative structure of the Tanzanian districts as sampling frame was used. Wards, villages and then participants with farms where pesticides are applied were purposively recruited at different stages of the process, 100 participants were enrolled in the study. The same villages were used for mosquito larvae sampling from the farms and the surveys were complimented by the entomological study. Larvae were reared in the insectary and the emerging 2–3 days old female adults of Anopheles gambiae s.l were subjected to susceptibility test. Results Forty eight pesticides of different formulations were used for control of crop and Livestock pests. Pyrethroids were the mostly used class of pesticides (50%) while organophosphates and carbamates were of secondary importance. Over 80% of all farmers applied pesticides in mixed form. Susceptibility test results confirmed high phenotypic resistance among An. gambiae populations against DDT and the pyrethroids (Permethrin-0.75%, Cyfluthrin-0.15%, Deltametrin-0.05% and Lambdacyhalothrin-0.05%) with mortality rates 54, 61, 76 and 71%, respectively. Molecular analysis showed An. arabiensis as a dominant species (86%) while An. gambiae s.s constituted only 6%. The kdr genes were not detected in all of the specimens that survived insecticide exposures. Conclusion The study found out that there is a common use of pyrethroids in farms, Livestocks as well as in public health. The study also reports high phenotypic resistance among An. gambiae s.l against most of the pyrethroids tested. The preponderance of pyrethroids in agriculture is of public health concern because this is the class of insecticides widely used in vector control programs and this calls for combined integrated pest and vector management (IPVM).
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Affiliation(s)
- Anitha Philbert
- Department of Zoology and Wildlife Conservation, University of Dar es Salaam, Dar es Salaam, Tanzania.
| | | | - Gamba Nkwengulila
- Department of Zoology and Wildlife Conservation, University of Dar es Salaam, Dar es Salaam, Tanzania
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15
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The impact of an insecticide treated bednet campaign on all-cause child mortality: A geospatial impact evaluation from the Democratic Republic of Congo. PLoS One 2019; 14:e0212890. [PMID: 30794694 PMCID: PMC6386397 DOI: 10.1371/journal.pone.0212890] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/11/2019] [Indexed: 11/19/2022] Open
Abstract
Objective To test the impact of a nationwide Long-Lasting Insecticidal Nets [LLINs] distribution program in the Democratic Republic of Congo [DRC] on all-cause under-five child mortality exploiting subnational variation in malaria endemicity and the timing in the scale-up of the program across provinces. Design Geospatial Impact Evaluation using a difference-in-differences approach. Setting Democratic Republic of the Congo. Participants 52,656 children sampled in the 2007 and 2013/2014 DRC Demographic and Health Surveys. Interventions The analysis provides plausibly causal estimates of both average treatment effects of the LLIN distribution campaign and geospatial heterogeneity in these effects based on malaria endemicity. It compares the under-five, all-cause mortality for children pre- and post-LLIN campaign relative to children in those areas that had not yet been exposed to the campaign using a difference-in-differences model and controlling for year- and province-fixed effects, and province-level trends in mortality. Results We find that the campaign led to a 41% decline [3.7 percentage points, 95% CI 1.3 to 6.0] in under-5 mortality risk among children living in rural areas with malaria ecology above the sample median. Results were robust to controlling for household assets and the presence of other health aid programs. No effect was detected in children living in areas with malaria ecology below the median. Conclusion The findings of this paper make important contributions to the evidence base for the effectiveness of large scale-national LLIN campaigns against malaria. We found that the program was effective in areas of the DRC with the highest underlying risk of malaria. Targeting bednets to areas with greatest underlying risk for malaria may help to increase the efficiency of increasingly limited malaria resources but should be balanced against other malaria control concerns.
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16
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Gari T, Lindtjørn B. Reshaping the vector control strategy for malaria elimination in Ethiopia in the context of current evidence and new tools: opportunities and challenges. Malar J 2018; 17:454. [PMID: 30518395 PMCID: PMC6282332 DOI: 10.1186/s12936-018-2607-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 12/01/2018] [Indexed: 12/20/2022] Open
Abstract
The core vector control measures, long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), reduce the risk of malaria infection by targeting indoor biting mosquitoes. These two interventions are found to be effective in malaria control, but not sufficient to eliminate malaria. The main challenges with LLINs and IRS are insecticide resistance, misuse of the interventions, host behaviour, such as staying out-door during early night or sleeping outdoor without using protective measures, and vector behaviour including feeding on bovine blood, outdoor biting and outdoor resting. Therefore, for complete interruption of malaria transmission in a defined area there is a need to consider a variety of interventions that can help prevent out-door as well as indoor malaria transmission. In Ethiopia, to achieve the malaria elimination goal, a mix of vector control tools, such as intensifying the use of LLINs and IRS, and supplemented by use of ivermectin administration, zooprophylaxis, odour-baited mosquito trapping, improving housing and larva control measures tailored to the local situation of malaria transmission, may be needed.
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Affiliation(s)
- Taye Gari
- School of Public Health, College of Medicine and Health Sciences, Hawassa University, Hawassa, Ethiopia.
| | - Bernt Lindtjørn
- Centre for International Health, University of Bergen, Bergen, Norway
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17
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Colborn KL, Giorgi E, Monaghan AJ, Gudo E, Candrinho B, Marrufo TJ, Colborn JM. Spatio-temporal modelling of weekly malaria incidence in children under 5 for early epidemic detection in Mozambique. Sci Rep 2018; 8:9238. [PMID: 29915366 PMCID: PMC6006329 DOI: 10.1038/s41598-018-27537-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 06/05/2018] [Indexed: 11/10/2022] Open
Abstract
Malaria is a major cause of morbidity and mortality in Mozambique. We present a malaria early warning system (MEWS) for Mozambique informed by seven years of weekly case reports of malaria in children under 5 years of age from 142 districts. A spatio-temporal model was developed based on explanatory climatic variables to map exceedance probabilities, defined as the predictive probability that the relative risk of malaria incidence in a given district for a particular week will exceed a predefined threshold. Unlike most spatially discrete models, our approach accounts for the geographical extent of each district in the derivation of the spatial covariance structure to allow for changes in administrative boundaries over time. The MEWS can thus be used to predict areas that may experience increases in malaria transmission beyond expected levels, early enough so that prevention and response measures can be implemented prior to the onset of outbreaks. The framework we present is also applicable to other climate-sensitive diseases.
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Affiliation(s)
- Kathryn L Colborn
- Department of Biostatistics and Informatics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Emanuele Giorgi
- Lancaster Medical School, Lancaster University, Lancaster, UK
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Massoda Tonye SG, Kouambeng C, Wounang R, Vounatsou P. Challenges of DHS and MIS to capture the entire pattern of malaria parasite risk and intervention effects in countries with different ecological zones: the case of Cameroon. Malar J 2018; 17:156. [PMID: 29625574 PMCID: PMC5889563 DOI: 10.1186/s12936-018-2284-7] [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: 07/28/2017] [Accepted: 03/21/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In 2011, the demographic and health survey (DHS) in Cameroon was combined with the multiple indicator cluster survey. Malaria parasitological data were collected, but the survey period did not overlap with the high malaria transmission season. A malaria indicator survey (MIS) was also conducted during the same year, within the malaria peak transmission season. This study compares estimates of the geographical distribution of malaria parasite risk and of the effects of interventions obtained from the DHS and MIS survey data. METHODS Bayesian geostatistical models were applied on DHS and MIS data to obtain georeferenced estimates of the malaria parasite prevalence and to assess the effects of interventions. Climatic predictors were retrieved from satellite sources. Geostatistical variable selection was used to identify the most important climatic predictors and indicators of malaria interventions. RESULTS The overall observed malaria parasite risk among children was 33 and 30% in the DHS and MIS data, respectively. Both datasets identified the Normalized Difference Vegetation Index and the altitude as important predictors of the geographical distribution of the disease. However, MIS selected additional climatic factors as important disease predictors. The magnitude of the estimated malaria parasite risk at national level was similar in both surveys. Nevertheless, DHS estimates lower risk in the North and Coastal areas. MIS did not find any important intervention effects, although DHS revealed that the proportion of population with an insecticide-treated nets access in their household was statistically important. An important negative relationship between malaria parasitaemia and socioeconomic factors, such as the level of mother's education, place of residence and the household welfare were captured by both surveys. CONCLUSION Timing of the malaria survey influences estimates of the geographical distribution of disease risk, especially in settings with seasonal transmission. In countries with different ecological zones and thus different seasonal patterns, a single survey may not be able to identify all high risk areas. A continuous MIS or a combination of MIS, health information system data and data from sentinel sites may be able to capture the disease risk distribution in space across different seasons.
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Affiliation(s)
- Salomon G Massoda Tonye
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,National Malaria Control Programme, Yaoundé, Cameroon
| | | | | | - Penelope Vounatsou
- Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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Alegana VA, Wright J, Bosco C, Okiro EA, Atkinson PM, Snow RW, Tatem AJ, Noor AM. Malaria prevalence metrics in low- and middle-income countries: an assessment of precision in nationally-representative surveys. Malar J 2017; 16:475. [PMID: 29162099 PMCID: PMC5697056 DOI: 10.1186/s12936-017-2127-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/16/2017] [Indexed: 12/28/2022] Open
Abstract
Background One pillar to monitoring progress towards the Sustainable Development Goals is the investment in high quality data to strengthen the scientific basis for decision-making. At present, nationally-representative surveys are the main source of data for establishing a scientific evidence base, monitoring, and evaluation of health metrics. However, little is known about the optimal precisions of various population-level health and development indicators that remains unquantified in nationally-representative household surveys. Here, a retrospective analysis of the precision of prevalence from these surveys was conducted. Methods Using malaria indicators, data were assembled in nine sub-Saharan African countries with at least two nationally-representative surveys. A Bayesian statistical model was used to estimate between- and within-cluster variability for fever and malaria prevalence, and insecticide-treated bed nets (ITNs) use in children under the age of 5 years. The intra-class correlation coefficient was estimated along with the optimal sample size for each indicator with associated uncertainty. Findings Results suggest that the estimated sample sizes for the current nationally-representative surveys increases with declining malaria prevalence. Comparison between the actual sample size and the modelled estimate showed a requirement to increase the sample size for parasite prevalence by up to 77.7% (95% Bayesian credible intervals 74.7–79.4) for the 2015 Kenya MIS (estimated sample size of children 0–4 years 7218 [7099–7288]), and 54.1% [50.1–56.5] for the 2014–2015 Rwanda DHS (12,220 [11,950–12,410]). Conclusion This study highlights the importance of defining indicator-relevant sample sizes to achieve the required precision in the current national surveys. While expanding the current surveys would need additional investment, the study highlights the need for improved approaches to cost effective sampling. Electronic supplementary material The online version of this article (10.1186/s12936-017-2127-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Victor A Alegana
- Geography and Environment, University of Southampton, Southampton, UK. .,Flowminder Foundation, Stockholm, Sweden.
| | - Jim Wright
- Geography and Environment, University of Southampton, Southampton, UK
| | - Claudio Bosco
- Geography and Environment, University of Southampton, Southampton, UK.,Flowminder Foundation, Stockholm, Sweden
| | - Emelda A Okiro
- Population Health Theme, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Peter M Atkinson
- Geography and Environment, University of Southampton, Southampton, UK.,Faculty of Science and Technology, Lancaster University, Lancaster, UK.,School of Geography, Archaeology and Palaeoecology, Queen's University Belfast, Belfast, BT7 1NN, Northern Ireland, UK
| | - Robert W Snow
- Population 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, OX3 7LJ, UK
| | - Andrew J Tatem
- Geography and Environment, University of Southampton, Southampton, UK.,Flowminder Foundation, Stockholm, Sweden
| | - Abdisalan M Noor
- Population 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, OX3 7LJ, UK.,World Health Organization, Geneva, Switzerland
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Florey LS, Bennett A, Hershey CL, Bhattarai A, Nielsen CF, Ali D, Luhanga M, Taylor C, Eisele TP, Yé Y. Impact of Insecticide-Treated Net Ownership on All-Cause Child Mortality in Malawi, 2006-2010. Am J Trop Med Hyg 2017; 97:65-75. [PMID: 28990922 PMCID: PMC5619930 DOI: 10.4269/ajtmh.15-0929] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Insecticide-treated nets (ITNs) have been shown to be highly effective at reducing malaria morbidity and mortality in children. However, there are limited studies that assess the association between increasing ITN coverage and child mortality over time, at the national level, and under programmatic conditions. Two analytic approaches were used to examine this association: a retrospective cohort analysis of individual children and a district-level ecologic analysis. To evaluate the association between household ITN ownership and all-cause child mortality (ACCM) at the individual level, data from the 2010 Demographic and Health Survey (DHS) were modeled in a Cox proportional hazards framework while controlling for numerous environmental, household, and individual confounders through the use of exact matching. To evaluate population-level association between ITN ownership and ACCM between 2006 and 2010, program ITN distribution data and mortality data from the 2006 Multiple Indicator Cluster Survey and the 2010 DHS were aggregated at the district level and modeled using negative binomial regression. In the Cox model controlling for household, child and maternal health factors, children between 1 and 59 months in households owning an ITN had significantly lower mortality compared with those without an ITN (hazard ratio = 0.75, 95% confidence interval [CI] = 0.62–90). In the district-level model, higher ITN ownership was significantly associated with lower ACCM (incidence rate ratio = 0.77; 95% CI = 0.60–0.98). These findings suggest that increasing ITN ownership may have contributed to the decline in ACCM during 2006–2010 in Malawi and represent a novel use of district-level data from nationally representative surveys.
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Affiliation(s)
| | - Adam Bennett
- Malaria Elimination Initiative, University of California, San Francisco, California
| | - Christine L Hershey
- President's Malaria Initiative, United States Agency for International Development, Arlington, Virginia
| | - Achuyt Bhattarai
- President's Malaria Initiative, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Carrie F Nielsen
- President's Malaria Initiative, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Doreen Ali
- National Malaria Control Programme, Ministry of Health, Lilongwe, Malawi
| | - Misheck Luhanga
- National Malaria Control Programme, Ministry of Health, Lilongwe, Malawi
| | | | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana
| | - Yazoume Yé
- ICF, MEASURE Evaluation, Rockville, Maryland
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Ssempiira J, Nambuusi B, Kissa J, Agaba B, Makumbi F, Kasasa S, Vounatsou P. The contribution of malaria control interventions on spatio-temporal changes of parasitaemia risk in Uganda during 2009-2014. Parasit Vectors 2017; 10:450. [PMID: 28964263 PMCID: PMC5622426 DOI: 10.1186/s13071-017-2393-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 09/19/2017] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND In Uganda, malaria vector control interventions and case management with Artemisinin Combination Therapies (ACTs) have been scaled up over the last few years as a result of increased funding. Data on parasitaemia prevalence among children less than 5 years old and coverage of interventions was collected during the first two Malaria Indicator Surveys (MIS) conducted in 2009 and 2014, respectively. In this study, we quantify the effects of control interventions on parasitaemia risk changes between the two MIS in a spatio-temporal analysis. METHODS Bayesian geostatistical and temporal models were fitted on the MIS data of 2009 and 2014. The models took into account geographical misalignment in the locations of the two surveys and adjusted for climatic changes and socio-economic differentials. Parasitaemia risk was predicted over a 2 × 2 km2 grid and the number of infected children less than 5 years old was estimated. Geostatistical variable selection was applied to identify the most important ITN coverage indicators. A spatially varying coefficient model was used to estimate intervention effects at sub-national level. RESULTS The coverage of Insecticide Treated Nets (ITNs) and ACTs more than doubled at country and sub-national levels during the period 2009-2014. The coverage of Indoor Residual Spraying (IRS) remained static at all levels. ITNs, IRS, and ACTs were associated with a reduction in parasitaemia odds of 19% (95% BCI: 18-29%), 78% (95% BCI: 67-84%), and 34% (95% BCI: 28-66%), respectively. Intervention effects varied with region. Higher socio-economic status and living in urban areas were associated with parasitaemia odds reduction of 46% (95% BCI: 0.51-0.57) and 57% (95% BCI: 0.40-0.53), respectively. The probability of parasitaemia risk decline in the country was 85% and varied from 70% in the North-East region to 100% in Kampala region. The estimated number of children infected with malaria declined from 2,480,373 in 2009 to 825,636 in 2014. CONCLUSIONS Interventions have had a strong effect on the decline of parasitaemia risk in Uganda during 2009-2014, albeit with varying magnitude in the regions. This success should be sustained by optimizing ITN coverage to achieve universal coverage.
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Affiliation(s)
- Julius Ssempiira
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Makerere University School of Public Health, Kampala, Uganda
| | - Betty Nambuusi
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Makerere University School of Public Health, Kampala, Uganda
| | | | | | | | - Simon Kasasa
- Makerere University School of Public Health, Kampala, Uganda
| | - Penelope Vounatsou
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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22
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Thomson MC, Ukawuba I, Hershey CL, Bennett A, Ceccato P, Lyon B, Dinku T. Using Rainfall and Temperature Data in the Evaluation of National Malaria Control Programs in Africa. Am J Trop Med Hyg 2017; 97:32-45. [PMID: 28990912 PMCID: PMC5619931 DOI: 10.4269/ajtmh.16-0696] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/29/2016] [Indexed: 11/17/2022] Open
Abstract
Since 2010, the Roll Back Malaria (RBM) Partnership, including National Malaria Control Programs, donor agencies (e.g., President's Malaria Initiative and Global Fund), and other stakeholders have been evaluating the impact of scaling up malaria control interventions on all-cause under-five mortality in several countries in sub-Saharan Africa. The evaluation framework assesses whether the deployed interventions have had an impact on malaria morbidity and mortality and requires consideration of potential nonintervention influencers of transmission, such as drought/floods or higher temperatures. Herein, we assess the likely effect of climate on the assessment of the impact malaria interventions in 10 priority countries/regions in eastern, western, and southern Africa for the President's Malaria Initiative. We used newly available quality controlled Enhanced National Climate Services rainfall and temperature products as well as global climate products to investigate likely impacts of climate on malaria evaluations and test the assumption that changing the baseline period can significantly impact on the influence of climate in the assessment of interventions. Based on current baseline periods used in national malaria impact assessments, we identify three countries/regions where current evaluations may overestimate the impact of interventions (Tanzania, Zanzibar, Uganda) and three countries where current malaria evaluations may underestimate the impact of interventions (Mali, Senegal and Ethiopia). In four countries (Rwanda, Malawi, Mozambique, and Angola) there was no strong difference in climate suitability for malaria in the pre- and post-intervention period. In part, this may be due to data quality and analysis issues.
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Affiliation(s)
- Madeleine C. Thomson
- International Research Institute for Climate and Society, Palisades, New York
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York
| | - Israel Ukawuba
- International Research Institute for Climate and Society, Palisades, New York
| | - Christine L. Hershey
- President's Malaria Initiative, United States Agency for International Development, Washington, District of Columbia
| | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, California
| | - Pietro Ceccato
- International Research Institute for Climate and Society, Palisades, New York
| | - Bradfield Lyon
- International Research Institute for Climate and Society, Palisades, New York
| | - Tufa Dinku
- International Research Institute for Climate and Society, Palisades, New York
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Ashton RA, Bennett A, Yukich J, Bhattarai A, Keating J, Eisele TP. Methodological Considerations for Use of Routine Health Information System Data to Evaluate Malaria Program Impact in an Era of Declining Malaria Transmission. Am J Trop Med Hyg 2017; 97:46-57. [PMID: 28990915 PMCID: PMC5619932 DOI: 10.4269/ajtmh.16-0734] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 10/24/2016] [Indexed: 12/01/2022] Open
Abstract
Coverage of malaria control interventions is increasing dramatically across endemic countries. Evaluating the impact of malaria control programs and specific interventions on health indicators is essential to enable countries to select the most effective and appropriate combination of tools to accelerate progress or proceed toward malaria elimination. When key malaria interventions have been proven effective under controlled settings, further evaluations of the impact of the intervention using randomized approaches may not be appropriate or ethical. Alternatives to randomized controlled trials are therefore required for rigorous evaluation under conditions of routine program delivery. Routine health management information system (HMIS) data are a potentially rich source of data for impact evaluation, but have been underused in impact evaluation due to concerns over internal validity, completeness, and potential bias in estimates of program or intervention impact. A range of methodologies were identified that have been used for impact evaluations with malaria outcome indicators generated from HMIS data. Methods used to maximize internal validity of HMIS data are presented, together with recommendations on reducing bias in impact estimates. Interrupted time series and dose-response analyses are proposed as the strongest quasi-experimental impact evaluation designs for analysis of malaria outcome indicators from routine HMIS data. Interrupted time series analysis compares the outcome trend and level before and after the introduction of an intervention, set of interventions or program. The dose-response national platform approach explores associations between intervention coverage or program intensity and the outcome at a subnational (district or health facility catchment) level.
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Affiliation(s)
- Ruth A. Ashton
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana
| | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California
| | - Joshua Yukich
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana
| | - Achuyt Bhattarai
- President's Malaria Initiative, Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Joseph Keating
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana
| | - Thomas P. Eisele
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, Louisiana
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McCord GC, Anttila-Hughes JK. A Malaria Ecology Index Predicted Spatial and Temporal Variation of Malaria Burden and Efficacy of Antimalarial Interventions Based on African Serological Data. Am J Trop Med Hyg 2017; 96:616-623. [PMID: 28070009 DOI: 10.4269/ajtmh.16-0602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Reducing the global health burden of malaria is complicated by weak reporting systems for infectious diseases and a paucity of vital statistics registration. This limits our ability to predict changes in malaria health burden intensity, target antimalarial resources where needed, and identify malaria impacts in retrospective data. We refined and deployed a temporally and spatially varying Malaria Ecology Index (MEI) incorporating climatological and ecological data to estimate malaria transmission strength and validate it against cross-sectional serology data from 39,875 children from seven sub-Saharan African countries. The MEI is strongly associated with malaria burden; a 1 standard deviation higher MEI is associated with a 50-117% increase in malaria risk and a 3-5 g/dL lower level of Hg. Results show that the relationship between malaria ecology and disease burden is attenuated with sufficient coverage of insecticide treated nets (ITNs) or indoor residual spraying (IRS). Having both ITNs and IRS reduce the added risk from adverse malaria ecology conditions by half. Readily available climate and ecology data can be used to estimate the spatial and temporal variation in malaria disease burden, providing a feasible alternative to direct surveillance. This will help target resources for malaria programs in the absence of national coverage of active case detection systems, and facilitate malaria research using retrospective health data.
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Affiliation(s)
- Gordon C McCord
- School of Global Policy and Strategy, University of California, San Diego, California
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Ssempiira J, Nambuusi B, Kissa J, Agaba B, Makumbi F, Kasasa S, Vounatsou P. Geostatistical modelling of malaria indicator survey data to assess the effects of interventions on the geographical distribution of malaria prevalence in children less than 5 years in Uganda. PLoS One 2017; 12:e0174948. [PMID: 28376112 PMCID: PMC5380319 DOI: 10.1371/journal.pone.0174948] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/19/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Malaria burden in Uganda has declined disproportionately among regions despite overall high intervention coverage across all regions. The Uganda Malaria Indicator Survey (MIS) 2014-15 was the second nationally representative survey conducted to provide estimates of malaria prevalence among children less than 5 years, and to track the progress of control interventions in the country. In this present study, 2014-15 MIS data were analysed to assess intervention effects on malaria prevalence in Uganda among children less than 5 years, assess intervention effects at regional level, and estimate geographical distribution of malaria prevalence in the country. METHODS Bayesian geostatistical models with spatially varying coefficients were used to determine the effect of interventions on malaria prevalence at national and regional levels. Spike-and-slab variable selection was used to identify the most important predictors and forms. Bayesian kriging was used to predict malaria prevalence at unsampled locations. RESULTS Indoor Residual Spraying (IRS) and Insecticide Treated Nets (ITN) ownership had a significant but varying protective effect on malaria prevalence. However, no effect was observed for Artemisinin Combination-based Therapies (ACTs). Environmental factors, namely, land cover, rainfall, day and night land surface temperature, and area type were significantly associated with malaria prevalence. Malaria prevalence was higher in rural areas, increased with the child's age, and decreased with higher household socioeconomic status and higher level of mother's education. The highest prevalence of malaria in children less than 5 years was predicted for regions of East Central, North East and West Nile, whereas the lowest was predicted in Kampala and South Western regions, and in the mountainous areas in Mid-Western and Mid-Eastern regions. CONCLUSIONS IRS and ITN ownership are important interventions against malaria prevalence in children less than 5 years in Uganda. The varying effects of the interventions calls for selective implementation of control tools suitable to regional ecological settings. To further reduce malaria burden and sustain malaria control in Uganda, current tools should be supplemented by health system strengthening, and socio-economic development.
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Affiliation(s)
- Julius Ssempiira
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- School of Public Health, Makerere University, Kampala, Uganda
| | - Betty Nambuusi
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- School of Public Health, Makerere University, Kampala, Uganda
| | | | | | | | - Simon Kasasa
- School of Public Health, Makerere University, Kampala, Uganda
| | - Penelope Vounatsou
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- * E-mail:
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26
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Rusk A, Highfield L, Wilkerson JM, Harrell M, Obala A, Amick B. Geographically-weighted regression of knowledge and behaviour determinants to anti-malarial recommending and dispensing practice among medicine retailers in western Kenya: capacitating targeted interventions. Malar J 2016; 15:562. [PMID: 27871303 PMCID: PMC5117492 DOI: 10.1186/s12936-016-1599-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 11/04/2016] [Indexed: 11/16/2022] Open
Abstract
Background Most patients with malaria seek treatment first in retail drug shops. Myriad studies have examined retailer behaviours and characteristics to understand the determinants to these behaviours. Geospatial methods are helpful in discovering if geographic location plays a role in the relationship between determinants and outcomes. This study aimed to discover if spatial autocorrelation exists in the relationship between determinants and retailer behaviours, and to provide specific geographic locations and target behaviours for tailoring future interventions. Methods Retailer behaviours and characteristics captured from a survey deployed to medicine retailers in the Webuye Demographic and Health Surveillance Site were analysed using geographic weighted regression to create prediction models for three separate outcomes: recommending the first-line anti-malarial therapy to adults, recommending the first-line anti-malarial therapy to children, and selling that therapy more than other anti-malarials. The estimated regression coefficients for each determinant, as well as the pseudo R2 values for each final model, were then mapped to assess spatial variability and local areas of best model fit. Results The relationships explored were found to be non-stationary, indicating that spatial heterogeneity exist in the data. The association between having a pharmacy-related health training and recommending the first-line anti-malarial treatment to adults was strongest around the peri-urban centre: comparing those with training in pharmacy to those without training (OR = 5.75, p = 0.021). The association between knowing the first-line anti-malarial and recommending it to children was strongest in the north of the study area compared to those who did not know the MOH-recommended anti-malarial (OR = 2.34, p = 0.070). This is also the area with the strongest association between attending a malaria workshop and selling the MOH-recommended anti-malarial more than other anti-malarials, compared to retailers who did not attend a workshop (OR = 2.38, p = 0.055). Conclusion Evidence suggests that spatial heterogeneity exists in these data, indicating that the relationship between determinants and behaviours varies across space. This is valuable information for intervention design, allowing efforts to focus on those factors that have the strongest relationship with their targeted behaviour within that geographic space, increasing programme efficiency and cost-effectiveness.
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Affiliation(s)
- Andria Rusk
- Dominican University of California, San Rafael, CA, USA. .,The University of Texas School of Public Health, Pressler Dr, Houston, TX, USA.
| | - Linda Highfield
- The University of Texas School of Public Health, Pressler Dr, Houston, TX, USA
| | - J Michael Wilkerson
- The University of Texas School of Public Health, Pressler Dr, Houston, TX, USA
| | - Melissa Harrell
- The University of Texas School of Public Health, Pressler Dr, Houston, TX, USA
| | - Andrew Obala
- Moi University School of Medicine, Nandi Rd, Eldoret, Kenya.,Webuye Demographic Surveillance Site Scientific Steering Committee, Eldoret, Kenya
| | - Benjamin Amick
- Department of Health Policy and Management, Robert Stempel College of Public Health & Social Work, Florida International University, Miami, FL, USA.,Institute for Work & Health, Toronto, Canada
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Houngbedji CA, Chammartin F, Yapi RB, Hürlimann E, N'Dri PB, Silué KD, Soro G, Koudou BG, Assi SB, N'Goran EK, Fantodji A, Utzinger J, Vounatsou P, Raso G. Spatial mapping and prediction of Plasmodium falciparum infection risk among school-aged children in Côte d'Ivoire. Parasit Vectors 2016; 9:494. [PMID: 27604807 PMCID: PMC5015250 DOI: 10.1186/s13071-016-1775-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 08/25/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In Côte d'Ivoire, malaria remains a major public health issue, and thus a priority to be tackled. The aim of this study was to identify spatially explicit indicators of Plasmodium falciparum infection among school-aged children and to undertake a model-based spatial prediction of P. falciparum infection risk using environmental predictors. METHODS A cross-sectional survey was conducted, including parasitological examinations and interviews with more than 5,000 children from 93 schools across Côte d'Ivoire. A finger-prick blood sample was obtained from each child to determine Plasmodium species-specific infection and parasitaemia using Giemsa-stained thick and thin blood films. Household socioeconomic status was assessed through asset ownership and household characteristics. Children were interviewed for preventive measures against malaria. Environmental data were gathered from satellite images and digitized maps. A Bayesian geostatistical stochastic search variable selection procedure was employed to identify factors related to P. falciparum infection risk. Bayesian geostatistical logistic regression models were used to map the spatial distribution of P. falciparum infection and to predict the infection prevalence at non-sampled locations via Bayesian kriging. RESULTS Complete data sets were available from 5,322 children aged 5-16 years across Côte d'Ivoire. P. falciparum was the predominant species (94.5 %). The Bayesian geostatistical variable selection procedure identified land cover and socioeconomic status as important predictors for infection risk with P. falciparum. Model-based prediction identified high P. falciparum infection risk in the north, central-east, south-east, west and south-west of Côte d'Ivoire. Low-risk areas were found in the south-eastern area close to Abidjan and the south-central and west-central part of the country. CONCLUSIONS The P. falciparum infection risk and related uncertainty estimates for school-aged children in Côte d'Ivoire represent the most up-to-date malaria risk maps. These tools can be used for spatial targeting of malaria control interventions.
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Affiliation(s)
- Clarisse A Houngbedji
- Unité de Formation et de Recherche Sciences de la Nature, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
- Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland
- University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Frédérique Chammartin
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland
- University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Richard B Yapi
- Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland
- University of Basel, P.O. Box, CH-4003, Basel, Switzerland
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 522, Abidjan 22, Côte d'Ivoire
| | - Eveline Hürlimann
- Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland
- University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Prisca B N'Dri
- Unité de Formation et de Recherche Sciences de la Nature, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
- Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland
- University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Kigbafori D Silué
- Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 522, Abidjan 22, Côte d'Ivoire
| | - Gotianwa Soro
- Programme National de Santé Scolaire et Universitaire, 01 BP 1725, Abidjan 01, Côte d'Ivoire
| | - Benjamin G Koudou
- Unité de Formation et de Recherche Sciences de la Nature, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
- Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
- Vector Group, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Serge-Brice Assi
- Institut Pierre Richet de Bouaké, Institut National de Santé Publique, BP 1500, Bouaké, Côte d'Ivoire
- Programme National de Lutte contre le Paludisme, Ministère de la Santé et de la Lutte contre le SIDA, BP V 4, Abidjan, Côte d'Ivoire
| | - Eliézer K N'Goran
- Département Environnement et Santé, Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 522, Abidjan 22, Côte d'Ivoire
| | - Agathe Fantodji
- Unité de Formation et de Recherche Sciences de la Nature, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
| | - Jürg Utzinger
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland
- University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Penelope Vounatsou
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland
- University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Giovanna Raso
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002, Basel, Switzerland.
- University of Basel, P.O. Box, CH-4003, Basel, Switzerland.
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Bennett A, Yukich J, Miller JM, Keating J, Moonga H, Hamainza B, Kamuliwo M, Andrade-Pacheco R, Vounatsou P, Steketee RW, Eisele TP. The relative contribution of climate variability and vector control coverage to changes in malaria parasite prevalence in Zambia 2006-2012. Parasit Vectors 2016; 9:431. [PMID: 27496161 PMCID: PMC4974721 DOI: 10.1186/s13071-016-1693-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 07/11/2016] [Indexed: 12/02/2022] Open
Abstract
Background Four malaria indicator surveys (MIS) were conducted in Zambia between 2006 and 2012 to evaluate malaria control scale-up. Nationally, coverage of insecticide-treated nets (ITNs) and indoor residual spraying (IRS) increased over this period, while parasite prevalence in children 1–59 months decreased dramatically between 2006 and 2008, but then increased from 2008 to 2010. We assessed the relative effects of vector control coverage and climate variability on malaria parasite prevalence over this period. Methods Nationally-representative MISs were conducted in April-June of 2006, 2008, 2010 and 2012 to collect household-level information on malaria control interventions such as IRS, ITN ownership and use, and child parasite prevalence by microscopic examination of blood smears. We fitted Bayesian geostatistical models to assess the association between IRS and ITN coverage and climate variability and malaria parasite prevalence. We created predictions of the spatial distribution of malaria prevalence at each time point and compared results of varying IRS, ITN, and climate inputs to assess their relative contributions to changes in prevalence. Results Nationally, the proportion of households owning an ITN increased from 37.8 % in 2006 to 64.3 % in 2010 and 68.1 % in 2012, with substantial heterogeneity sub-nationally. The population-adjusted predicted child malaria parasite prevalence decreased from 19.6 % in 2006 to 10.4 % in 2008, but rose to 15.3 % in 2010 and 13.5 % in 2012. We estimated that the majority of this prevalence increase at the national level between 2008 and 2010 was due to climate effects on transmission, although there was substantial heterogeneity at the provincial level in the relative contribution of changing climate and ITN availability. We predict that if climate factors preceding the 2010 survey were the same as in 2008, the population-adjusted prevalence would have fallen to 9.9 % nationally. Conclusions These results suggest that a combination of climate factors and reduced intervention coverage in parts of the country contributed to both the reduction and rebound in malaria parasite prevalence. Unusual rainfall patterns, perhaps related to moderate El Niño conditions, may have contributed to this variation. Zambia has demonstrated considerable success in scaling up vector control. This analysis highlights the importance of accounting for climate variability when using cross-sectional data for evaluation of malaria control efforts. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1693-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California, 500 16th St, San Francisco, CA, 94158, USA. .,Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA.
| | - Josh Yukich
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - John M Miller
- PATH Malaria Control and Evaluation Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Joseph Keating
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - Hawela Moonga
- National Malaria Control Centre, Ministry of Health, Lusaka, Zambia
| | - Busiku Hamainza
- National Malaria Control Centre, Ministry of Health, Lusaka, Zambia
| | - Mulakwa Kamuliwo
- National Malaria Control Centre, Ministry of Health, Lusaka, Zambia
| | - Ricardo Andrade-Pacheco
- Malaria Elimination Initiative, Global Health Group, University of California, 500 16th St, San Francisco, CA, 94158, USA
| | - Penelope Vounatsou
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Richard W Steketee
- PATH Malaria Control and Evaluation Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
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Jaleta KT, Hill SR, Birgersson G, Tekie H, Ignell R. Chicken volatiles repel host-seeking malaria mosquitoes. Malar J 2016; 15:354. [PMID: 27439360 PMCID: PMC4955153 DOI: 10.1186/s12936-016-1386-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 06/14/2016] [Indexed: 12/03/2022] Open
Abstract
Background Anopheles arabiensis is a dominant vector of malaria in sub-Saharan Africa, which feeds indoors and outdoors on human and other vertebrate hosts, making it a difficult species to control with existing control methods. Novel methods that reduce human-vector interactions are, therefore, required to improve the impact of vector control programmes. Investigating the mechanisms underlying the host discrimination process in An. arabiensis could provide valuable knowledge leading to the development of novel control technologies. In this study, a host census and blood meal analysis were conducted to determine the host selection behaviour of An. arabiensis. Since mosquitoes select and discriminate among hosts primarily using olfaction, the volatile headspace of the preferred non-human host and non-host species, were collected. Using combined gas chromatography and electroantennographic detection analysis followed by combined gas chromatography and mass spectrometry, the bioactive compounds in the headspace collections were identified. The efficiency of the identified non-host compounds to repel host-seeking malaria mosquitoes was tested under field conditions. Results The host census and blood meal analyses demonstrated that An. arabiensis strongly prefers human blood when host seeking indoors, while it randomly feeds on cattle, goats and sheep when found outdoors. However, An. arabiensis avoids chickens despite their relatively high abundance, indicating that chickens are a non-host species for this vector. Eleven bioactive compounds were found in the headspace of the non-host species. Six of these were species-specific, out of which four were identified using combined gas chromatography and mass spectrometry. When tested in the field, the chicken-specific compounds, isobutyl butyrate, naphthalene, hexadecane and trans-limonene oxide, and the generic host compounds, limonene, cis-limonene oxide and β-myrcene, significantly reduced trap catches within the house compared to a negative control. A significant reduction in trap catch was also observed when suspending a caged chicken next to the trap. Conclusions Non-host volatiles repel host-seeking An. arabiensis and thus play a significant role in host discrimination. As such, this study demonstrates that non-host volatiles can provide protection to humans at risk of mosquito-vectored diseases in combination with established control programmes. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1386-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kassahun T Jaleta
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P. O. Box 102, 23053, Alnarp, Sweden.,Department of Zoological Sciences, College of Natural Science, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
| | - Sharon Rose Hill
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P. O. Box 102, 23053, Alnarp, Sweden
| | - Göran Birgersson
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P. O. Box 102, 23053, Alnarp, Sweden
| | - Habte Tekie
- Department of Zoological Sciences, College of Natural Science, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
| | - Rickard Ignell
- Unit of Chemical Ecology, Department of Plant Protection Biology, Swedish University of Agricultural Sciences, P. O. Box 102, 23053, Alnarp, Sweden.
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Anyanwu JN, Williams O, Sautter CL, Kasirye P, Hume H, Opoka RO, Latham T, Ndugwa C, Ware RE, John CC. Novel Use of Hydroxyurea in an African Region With Malaria: Protocol for a Randomized Controlled Clinical Trial. JMIR Res Protoc 2016; 5:e110. [PMID: 27339303 PMCID: PMC4937184 DOI: 10.2196/resprot.5599] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/03/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Sickle cell anemia (SCA), one of most prevalent monogenic diseases worldwide, is caused by a glutamic acid to valine substitution on the beta globin protein of hemoglobin, which leads to hemolytic anemia. Hydroxyurea, the only disease-modifying therapy approved by the Food and Drug Administration for SCA, has proven to be a viable therapeutic option for SCA patients in resource-rich settings, given clinical improvements experienced while taking the medication and its once-daily oral dosing. Significant studies have demonstrated its safety and clinical efficacy among children and adults in developed countries. In Sub-Saharan Africa, however, the risk of malaria, hematologic toxicities, and safety of hydroxyurea in children with SCA living in malaria-endemic areas are unknown. OBJECTIVES Study objectives include determining the incidence of malaria in SCA patients taking hydroxyurea versus placebo; establishing the frequency of hematologic toxicities and adverse events (AEs) in children with SCA treated with hydroxyurea versus placebo; and defining the relationships between hydroxyurea treatment and fetal hemoglobin, soluble intracellular adhesion molecule-1, and nitric oxide levels, and between levels of these factors and risk of subsequent malaria. METHODS Novel use Of Hydroxyurea in an African Region with Malaria (NOHARM, NCT01976416) is a prospective, randomized, placebo-controlled, double-blinded phase III trial to compare risk of malaria with oral hydroxyurea versus placebo. Children will be recruited from the Mulago Hospital Sickle Cell Clinic in Kampala, Uganda. RESULTS Two hundred Ugandan children aged between 1.00 and 3.99 years with confirmed SCA will be randomized into treatment groups by order of entry in the study, based on a predetermined blinded randomization list. The primary outcome of the trial is malaria incidence in the 2 study groups, defined as episodes of clinical malaria occurring over the 1-year randomized study treatment period. CONCLUSION NOHARM will be the first prospective randomized, placebo-controlled clinical trial investigating the use of hydroxyurea for children with SCA in a malaria-endemic region within Africa. The results of this trial have the potential to significantly advance understanding of how to safely and effectively use hydroxyurea in children with SCA in malaria-endemic areas. TRIAL REGISTRATION Clinicaltrials.gov NCT01976416; https://clinicaltrials.gov/ct2/show/NCT01976416 (Archived by WebCite at http://www.webcitation.org/6hmoilZnp).
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Ndo C, Kopya E, Menze-Djantio B, Toto JC, Awono-Ambene P, Lycett G, Wondji CS. High susceptibility of wild Anopheles funestus to infection with natural Plasmodium falciparum gametocytes using membrane feeding assays. Parasit Vectors 2016; 9:341. [PMID: 27301693 PMCID: PMC4908716 DOI: 10.1186/s13071-016-1626-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 06/07/2016] [Indexed: 01/15/2023] Open
Abstract
Background Anopheles funestus is a major vector of malaria in sub-Saharan Africa. However, because it is difficult to colonize, research on this mosquito species has lagged behind other vectors, particularly the understanding of its susceptibility and interactions with the Plasmodium parasite. The present study reports one of the first experimental infections of progeny from wild-caught An. funestus with the P. falciparum parasite providing a realistic avenue for the characterisation of immune responses associated with this infection. Methods Wild-fed resting An. funestus females were collected using electric aspirators and kept in cages for four days until they were fully gravid and ready to oviposit. The resulting eggs were reared to adults F1 mosquitoes under insectary conditions. Three to five day-old An. funestus F1 females were fed with infected blood taken from gametocyte carriers using an artificial glass-parafilm feeding system. Feeding rate was recorded and fed mosquitoes were dissected at day 7 to count oocysts in midguts. Parallel experiments were performed with the known Plasmodium-susceptible An. coluzzii Ngousso laboratory strain, to monitor our blood handling procedures and infectivity of gametocytes. Results The results revealed that An. funestus displays high and similar level of susceptibility to Plasmodium infection compared to An. coluzzii, and suggest that our methodology produces robust feeding and infection rates in wild An. funestus progeny. The prevalence of infection in An. funestus mosquitoes was 38.52 % (range 6.25–100 %) and the median oocyst number was 12.5 (range 1–139). In parallel, the prevalence in An. coluzzii was 39.92 % (range 6.85–97.5 %), while the median oocyst number was 32.1 (range 1–351). Conclusions Overall, our observations are in line with the fact that both species are readily infected with P. falciparum, the most common and dangerous malaria parasite in sub-Saharan Africa, and since An. funestus is widespread throughout Africa, malaria vector control research and implementation needs to seriously address this vector species too. Additionally, the present work indicates that it is feasible to generate large number of wild F1 infected An. funestus mosquitoes using membrane feeding assays, which can be used for comprehensive study of interactions with the Plasmodium parasite. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1626-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cyrille Ndo
- Malaria Research Laboratory, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon. .,Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. .,Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O. Box 2701, Douala, Cameroon.
| | - Edmond Kopya
- Malaria Research Laboratory, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon.,Faculty of Sciences, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Benjamin Menze-Djantio
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.,Research Unit Liverpool School of Tropical Medicine, OCEAC, P.O. Box 288, Yaoundé, Cameroon
| | - Jean Claude Toto
- Malaria Research Laboratory, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
| | - Parfait Awono-Ambene
- Malaria Research Laboratory, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
| | - Gareth Lycett
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Charles S Wondji
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.,Research Unit Liverpool School of Tropical Medicine, OCEAC, P.O. Box 288, Yaoundé, Cameroon
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Kazembe LN, Mathanga DP. Estimating risk factors of urban malaria in Blantyre, Malawi: A spatial regression analysis. Asian Pac J Trop Biomed 2016. [DOI: 10.1016/j.apjtb.2016.03.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Diboulo E, Sié A, Vounatsou P. Assessing the effects of malaria interventions on the geographical distribution of parasitaemia risk in Burkina Faso. Malar J 2016; 15:228. [PMID: 27098853 PMCID: PMC4839146 DOI: 10.1186/s12936-016-1282-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 04/12/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Burkina Faso conducted its first nationally representative household malaria survey in 2010/2011. The survey collected among others, information on malaria interventions, treatment choices and malaria parasite prevalence in children aged 6-59 months. METHODS In this study, Bayesian geostatistical models were employed to assess the effects of health interventions related to insecticide-treated bed nets (ITN), indoor residual spray (IRS), artemisinin-based combination therapy (ACT) coverage associated with childhood malaria parasite risk at national and sub-national level, after taking into account geographical disparities of climatic/environmental and socio-economic factors. Several ITN coverage measures were calculated and Bayesian variable selection was used to identify the most important ones. Parasitaemia risk depicting spatial patterns of infections were estimated. RESULTS The results show that the predicted population-adjusted parasitaemia risk ranges from 4.04 % in Kadiogo province to 82 % in Kompienga province. The effect of ITN coverage was not important at national level; however ITNs have an important protective effect in Ouagadougou as well as in three districts in the western part of the country with high parasitaemia prevalence and low to moderate coverage. There is a large variation in ACT coverage between the districts. Although at national level the ACT effects on parasitaemia risk was not important, at sub-national level 18 districts around Ouagadougou deliver effective treatment. CONCLUSION The produced maps show great variations in parasitaemia risk across the country and identify the districts where interventions are being effective. These outputs are valuable tools that can help improve malaria control in Burkina Faso.
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Affiliation(s)
- Eric Diboulo
- />Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland
- />University of Basel, Basel, Switzerland
- />Centre de Recherche en Santé de Nouna, Nouna, Burkina Faso
| | - Ali Sié
- />Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland
| | - Penelope Vounatsou
- />Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland
- />University of Basel, Basel, Switzerland
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Das S, Muleba M, Stevenson JC, Norris DE. Habitat Partitioning of Malaria Vectors in Nchelenge District, Zambia. Am J Trop Med Hyg 2016; 94:1234-44. [PMID: 27001755 DOI: 10.4269/ajtmh.15-0735] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 02/07/2016] [Indexed: 11/07/2022] Open
Abstract
Nchelenge District in Luapula Province, northern Zambia, experiences holoendemic malaria despite implementation of vector control programs. The major Anopheles vectors that contribute to Plasmodium falciparum transmission in this area had not previously been well defined. Three collections performed during the 2012 wet and dry seasons and the 2013 wet season revealed Anopheles funestus sensu stricto and Anopheles gambiae sensu stricto as the main vectors, where 80-85% of each collection was composed of An. funestus Both vectors were found to be highly anthropophilic, and An. funestus has higher sporozoite infection rates (SIRs) and entomological inoculation rates (EIRs) year-round compared with An. gambiae: SIRs of 1.8-3.0% and 0-2.5%, respectively, and EIRs of 3.7-41.5 infectious bites per 6-month period (ib/p/6mo) and 0-5.9 ib/p/6mo, respectively. Spatial and temporal changes in each vector's dynamics and bionomics were also observed. Anopheles funestus was the predominant vector in the villages near Kenani Stream in both wet and dry seasons, whereas An. gambiae was found to be the main vector in areas near Lake Mweru during the wet season. The vector data illustrate the need for broader temporal and spatial sampling in Nchelenge and present unique opportunities to further our understanding of malarial transmission and implications for malarial control in high-risk areas.
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Affiliation(s)
- Smita Das
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Tropical Disease Research Centre, Ndola Central Hospital, Ndola, Zambia; Macha Research Trust, Choma, Zambia
| | - Mbanga Muleba
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Tropical Disease Research Centre, Ndola Central Hospital, Ndola, Zambia; Macha Research Trust, Choma, Zambia
| | - Jennifer C Stevenson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland; Tropical Disease Research Centre, Ndola Central Hospital, Ndola, Zambia; Macha Research Trust, Choma, Zambia
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Rusk A, Highfield L, Wilkerson JM, Harrell M, Obala A, Amick B. Spatial distribution and cluster analysis of retail drug shop characteristics and antimalarial behaviors as reported by private medicine retailers in western Kenya: informing future interventions. Int J Health Geogr 2016; 15:9. [PMID: 26896165 PMCID: PMC4759713 DOI: 10.1186/s12942-016-0038-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 02/08/2016] [Indexed: 01/04/2023] Open
Abstract
Background
Efforts to improve malaria case management in sub-Saharan Africa have shifted focus to private antimalarial retailers to increase access to appropriate treatment. Demands to decrease intervention cost while increasing efficacy requires interventions tailored to geographic regions with demonstrated need. Cluster analysis presents an opportunity to meet this demand, but has not been applied to the retail sector or antimalarial retailer behaviors. This research conducted cluster analysis on medicine retailer behaviors in Kenya, to improve malaria case management and inform future interventions. Methods Ninety-seven surveys were collected from medicine retailers working in the Webuye Health and Demographic Surveillance Site. Survey items included retailer training, education, antimalarial drug knowledge, recommending behavior, sales, and shop characteristics, and were analyzed using Kulldorff’s spatial scan statistic. The Bernoulli purely spatial model for binomial data was used, comparing cases to controls. Statistical significance of found clusters was tested with a likelihood ratio test, using the null hypothesis of no clustering, and a p value based on 999 Monte Carlo simulations. The null hypothesis was rejected with p values of 0.05 or less. Results A statistically significant cluster of fewer than expected pharmacy-trained retailers was found (RR = .09, p = .001) when compared to the expected random distribution. Drug recommending behavior also yielded a statistically significant cluster, with fewer than expected retailers recommending the correct antimalarial medication to adults (RR = .018, p = .01), and fewer than expected shops selling that medication more often than outdated antimalarials when compared to random distribution (RR = 0.23, p = .007). All three of these clusters were co-located, overlapping in the northwest of the study area. Conclusion Spatial clustering was found in the data. A concerning amount of correlation was found in one specific region in the study area where multiple behaviors converged in space, highlighting a prime target for interventions. These results also demonstrate the utility of applying geospatial methods in the study of medicine retailer behaviors, making the case for expanding this approach to other regions.
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Affiliation(s)
- Andria Rusk
- The University of Texas School of Public Health, Pressler Dr, Houston, TX, USA.
| | - Linda Highfield
- The University of Texas School of Public Health, Pressler Dr, Houston, TX, USA.
| | - J Michael Wilkerson
- The University of Texas School of Public Health, Pressler Dr, Houston, TX, USA.
| | - Melissa Harrell
- The University of Texas School of Public Health, Pressler Dr, Houston, TX, USA.
| | - Andrew Obala
- Moi University School of Medicine, Nandi Rd, Eldoret, Kenya. .,Webuye Demographic Surveillance Site Scientific Steering Committee, Eldoret, Kenya.
| | - Benjamin Amick
- Department of Health Policy and Management, Florida International University, Robert Stempel College of Public Health and Social Work, Miami, FL, USA. .,Institute for Work and Health, Toronto, Canada.
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Cadavid Restrepo AM, Yang YR, McManus DP, Gray DJ, Giraudoux P, Barnes TS, Williams GM, Soares Magalhães RJ, Hamm NAS, Clements ACA. The landscape epidemiology of echinococcoses. Infect Dis Poverty 2016; 5:13. [PMID: 26895758 PMCID: PMC4759770 DOI: 10.1186/s40249-016-0109-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 02/15/2016] [Indexed: 12/29/2022] Open
Abstract
Echinococcoses are parasitic diseases of major public health importance globally. Human infection results in chronic disease with poor prognosis and serious medical, social and economic consequences for vulnerable populations. According to recent estimates, the geographical distribution of Echinococcus spp. infections is expanding and becoming an emerging and re-emerging problem in several regions of the world. Echinococcosis endemicity is geographically heterogeneous and over time it may be affected by global environmental change. Therefore, landscape epidemiology offers a unique opportunity to quantify and predict the ecological risk of infection at multiple spatial and temporal scales. Here, we review the most relevant environmental sources of spatial variation in human echinococcosis risk, and describe the potential applications of landscape epidemiological studies to characterise the current patterns of parasite transmission across natural and human-altered landscapes. We advocate future work promoting the use of this approach as a support tool for decision-making that facilitates the design, implementation and monitoring of spatially targeted interventions to reduce the burden of human echinococcoses in disease-endemic areas.
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Affiliation(s)
- Angela M Cadavid Restrepo
- Research School of Population Health, The Australian National University, Canberra, New South Wales, Australia.
| | - Yu Rong Yang
- Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region, P. R. China.
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
| | - Donald P McManus
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
| | - Darren J Gray
- Research School of Population Health, The Australian National University, Canberra, New South Wales, Australia.
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
| | - Patrick Giraudoux
- Chrono-environment lab, UMR6249, University of Bourgogne Franche-Comté/CNRS, Besançon, France.
- Institut Universitaire de France, Paris, France.
| | - Tamsin S Barnes
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia.
- The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, Gatton, Queensland, Australia.
| | - Gail M Williams
- School of Public Health, The University of Queensland, Brisbane, Queensland, Australia.
| | - Ricardo J Soares Magalhães
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia.
- Child Health Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
| | - Nicholas A S Hamm
- Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede, The Netherlands.
| | - Archie C A Clements
- Research School of Population Health, The Australian National University, Canberra, New South Wales, Australia.
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Homan T, Maire N, Hiscox A, Di Pasquale A, Kiche I, Onoka K, Mweresa C, Mukabana WR, Ross A, Smith TA, Takken W. Spatially variable risk factors for malaria in a geographically heterogeneous landscape, western Kenya: an explorative study. Malar J 2016; 15:1. [PMID: 26729363 PMCID: PMC4700570 DOI: 10.1186/s12936-015-1044-1] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 12/09/2015] [Indexed: 11/17/2022] Open
Abstract
Background Large reductions in malaria transmission and mortality have been achieved over the last decade, and this has mainly been attributed to the scale-up of long-lasting insecticidal bed nets and indoor residual spraying with insecticides. Despite these gains considerable residual, spatially heterogeneous, transmission remains. To reduce transmission in these foci, researchers need to consider the local demographical, environmental and social context, and design an appropriate set of interventions. Exploring spatially variable risk factors for malaria can give insight into which human and environmental characteristics play important roles in sustaining malaria transmission. Methods On Rusinga Island, western Kenya, malaria infection was tested by rapid diagnostic tests during two cross-sectional surveys conducted 3 months apart in 3632 individuals from 790 households. For all households demographic data were collected by means of questionnaires. Environmental variables were derived using Quickbird satellite images. Analyses were performed on 81 project clusters constructed by a traveling salesman algorithm, each containing 50–51 households. A standard linear regression model was fitted containing multiple variables to determine how much of the spatial variation in malaria prevalence could be explained by the demographic and environmental data. Subsequently, a geographically-weighted regression (GWR) was performed assuming non-stationarity of risk factors. Special attention was taken to investigate the effect of residual spatial autocorrelation and local multicollinearity. Results Combining the data from both surveys, overall malaria prevalence was 24 %. Scan statistics revealed two clusters which had significantly elevated numbers of malaria cases compared to the background prevalence across the rest of the study area. A multivariable linear model including environmental and household factors revealed that higher socioeconomic status, outdoor occupation and population density were associated with increased malaria risk. The local GWR model improved the model fit considerably and the relationship of malaria with risk factors was found to vary spatially over the island; in different areas of the island socio-economic status, outdoor occupation and population density were found to be positively or negatively associated with malaria prevalence. Discussion Identification of risk factors for malaria that vary geographically can provide insight into the local epidemiology of malaria. Examining spatially variable relationships can be a helpful tool in exploring which set of targeted interventions could locally be implemented. Supplementary malaria control may be directed at areas, which are identified as at risk. For instance, areas with many people that work outdoors at night may need more focus in terms of vector control. Trial registration: Trialregister.nl NTR3496—SolarMal, registered on 20 June 2012
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Affiliation(s)
- Tobias Homan
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands.
| | - Nicolas Maire
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Alexandra Hiscox
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands.
| | - Aurelio Di Pasquale
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Ibrahim Kiche
- Department of Medical Entomology, International Centre of Insect Physiology and Ecology, Nairobi, Kenya.
| | - Kelvin Onoka
- Department of Medical Entomology, International Centre of Insect Physiology and Ecology, Nairobi, Kenya.
| | - Collins Mweresa
- Department of Medical Entomology, International Centre of Insect Physiology and Ecology, Nairobi, Kenya.
| | | | - Amanda Ross
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Thomas A Smith
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research Centre, Wageningen, The Netherlands.
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O’Regan SM, Lillie JW, Drake JM. Leading indicators of mosquito-borne disease elimination. THEOR ECOL-NETH 2015; 9:269-286. [PMID: 27512522 PMCID: PMC4960289 DOI: 10.1007/s12080-015-0285-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 11/12/2015] [Indexed: 12/03/2022]
Abstract
Mosquito-borne diseases contribute significantly to the global disease burden. High-profile elimination campaigns are currently underway for many parasites, e.g., Plasmodium spp., the causal agent of malaria. Sustaining momentum near the end of elimination programs is often difficult to achieve and consequently quantitative tools that enable monitoring the effectiveness of elimination activities after the initial reduction of cases has occurred are needed. Documenting progress in vector-borne disease elimination is a potentially important application for the theory of critical transitions. Non-parametric approaches that are independent of model-fitting would advance infectious disease forecasting significantly. In this paper, we consider compartmental Ross-McDonald models that are slowly forced through a critical transition through gradually deployed control measures. We derive expressions for the behavior of candidate indicators, including the autocorrelation coefficient, variance, and coefficient of variation in the number of human cases during the approach to elimination. We conducted a simulation study to test the performance of each summary statistic as an early warning system of mosquito-borne disease elimination. Variance and coefficient of variation were highly predictive of elimination but autocorrelation performed poorly as an indicator in some control contexts. Our results suggest that tipping points (bifurcations) in mosquito-borne infectious disease systems may be foreshadowed by characteristic temporal patterns of disease prevalence.
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Affiliation(s)
- Suzanne M. O’Regan
- Odum School of Ecology, University of Georgia, Athens, GA 30602-2202 USA
- National Institute for Mathematical and Biological Synthesis (NIMBioS), 1122 Volunteer Boulevard, University of Tennessee, Knoxville, TN 37996-3410 USA
| | | | - John M. Drake
- Odum School of Ecology, University of Georgia, Athens, GA 30602-2202 USA
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Kastner RJ, Stone CM, Steinmann P, Tanner M, Tediosi F. What Is Needed to Eradicate Lymphatic Filariasis? A Model-Based Assessment on the Impact of Scaling Up Mass Drug Administration Programs. PLoS Negl Trop Dis 2015; 9:e0004147. [PMID: 26451729 PMCID: PMC4599939 DOI: 10.1371/journal.pntd.0004147] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 09/17/2015] [Indexed: 11/18/2022] Open
Abstract
Background Lymphatic filariasis (LF) is a neglected tropical disease for which more than a billion people in 73 countries are thought to be at-risk. At a global level, the efforts against LF are designed as an elimination program. However, current efforts appear to aim for elimination in some but not all endemic areas. With the 2020 goal of elimination looming, we set out to develop plausible scale-up scenarios to reach global elimination and eradication. We predict the duration of mass drug administration (MDA) necessary to reach local elimination for a variety of transmission archetypes using an existing model of LF transmission, estimate the number of treatments required for each scenario, and consider implications of rapid scale-up. Methodology We have defined four scenarios that differ in their geographic coverage and rate of scale-up. For each scenario, country-specific simulations and calculations were performed that took into account the pre-intervention transmission intensity, the different vector genera, drug regimen, achieved level of population coverage, previous progress toward elimination, and potential programmatic delays due to mapping, operations, and administration. Principal Findings Our results indicate that eliminating LF by 2020 is unlikely. If MDA programs are drastically scaled up and expanded, the final round of MDA for LF eradication could be delivered in 2028 after 4,159 million treatments. However, if the current rate of scale-up is maintained, the final round of MDA to eradicate LF may not occur until 2050. Conclusions/Significance Rapid scale-up of MDA will decrease the amount of time and treatments required to reach LF eradication. It may also propel the program towards success, as the risk of failure is likely to increase with extended program duration. Lymphatic filariasis (LF) is a disease caused by filarial worms transmitted by different types of mosquitos that can lead to massive disability, including elephantiasis and hydrocele. LF has no significant zoonotic reservoir and is thought to be a potentially eradicable disease through once yearly treatment distributed by mass drug administration (MDA). In this study, we set out to determine how many treatments and over how much time it might take to globally eliminate and eradicate LF under different levels of treatment intensities. We created a model that took into account country-specific and disease-specific variables, and found that if the current intensity of MDA is maintained, 3,409 million treatments distributed over the next 37 years will be required. However, if treatment is rapidly expanded to the entire at-risk population in all endemic countries, eradication could be achieved with 4,159 million treatments and in less than half the time. While our estimates suggest more time may be needed to reach LF elimination than what is currently projected, with continued commitment, eradicating LF is within reach.
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Affiliation(s)
- Randee J. Kastner
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Christopher M. Stone
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Peter Steinmann
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Marcel Tanner
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Fabrizio Tediosi
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- * E-mail:
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Bhatt S, Weiss D, Cameron E, Bisanzio D, Mappin B, Dalrymple U, Battle K, Moyes C, Henry A, Eckhoff P, Wenger E, Briët O, Penny M, Smith T, Bennett A, Yukich J, Eisele T, Griffin J, Fergus C, Lynch M, Lindgren F, Cohen J, Murray C, Smith D, Hay S, Cibulskis R, Gething P. The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015. Nature 2015; 526:207-211. [PMID: 26375008 PMCID: PMC4820050 DOI: 10.1038/nature15535] [Citation(s) in RCA: 1726] [Impact Index Per Article: 191.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 09/01/2015] [Indexed: 12/15/2022]
Abstract
Since the year 2000, a concerted campaign against malaria has led to unprecedented levels of intervention coverage across sub-Saharan Africa. Understanding the effect of this control effort is vital to inform future control planning. However, the effect of malaria interventions across the varied epidemiological settings of Africa remains poorly understood owing to the absence of reliable surveillance data and the simplistic approaches underlying current disease estimates. Here we link a large database of malaria field surveys with detailed reconstructions of changing intervention coverage to directly evaluate trends from 2000 to 2015, and quantify the attributable effect of malaria disease control efforts. We found that Plasmodium falciparum infection prevalence in endemic Africa halved and the incidence of clinical disease fell by 40% between 2000 and 2015. We estimate that interventions have averted 663 (542-753 credible interval) million clinical cases since 2000. Insecticide-treated nets, the most widespread intervention, were by far the largest contributor (68% of cases averted). Although still below target levels, current malaria interventions have substantially reduced malaria disease incidence across the continent. Increasing access to these interventions, and maintaining their effectiveness in the face of insecticide and drug resistance, should form a cornerstone of post-2015 control strategies.
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Affiliation(s)
- S. Bhatt
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - D.J. Weiss
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - E. Cameron
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - D. Bisanzio
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - B. Mappin
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - U. Dalrymple
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - K. Battle
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - C.L. Moyes
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - A. Henry
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - P.A. Eckhoff
- Institute for Disease Modeling, Intellectual Ventures, 1555 132nd Ave NE, Bellevue, WA 98005, USA
| | - E.A. Wenger
- Institute for Disease Modeling, Intellectual Ventures, 1555 132nd Ave NE, Bellevue, WA 98005, USA
| | - O. Briët
- Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. BOX 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, P.O. BOX 4001, Basel, Switzerland
| | - M.A. Penny
- Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. BOX 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, P.O. BOX 4001, Basel, Switzerland
| | - T.A. Smith
- Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. BOX 4002, Basel, Switzerland
- University of Basel, Petersplatz 1, P.O. BOX 4001, Basel, Switzerland
| | - A. Bennett
- Malaria Elimination Initiative, University of California San Francisco, 500 Parnassus Ave, San Francisco, CA 94143, San Francisco, USA
| | - J. Yukich
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, 1440 Canal Street, Suite 2200 New Orleans, LA 70112, USA
| | - T.P. Eisele
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, 1440 Canal Street, Suite 2200 New Orleans, LA 70112, USA
| | - J.T. Griffin
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK
| | - C.A. Fergus
- Global Malaria Programme, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland
| | - M. Lynch
- Global Malaria Programme, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland
| | - F. Lindgren
- Department of Mathematical Sciences, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - J.M. Cohen
- Clinton Health Access Initiative, Boston, MA, USA
| | - C.L.J. Murray
- Institute for Health Metrics and Evaluation, 2301 Fifth Ave., Suite 600, Seattle, WA 98121, USA
| | - D.L. Smith
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
- Institute for Health Metrics and Evaluation, 2301 Fifth Ave., Suite 600, Seattle, WA 98121, USA
- Sanaria Institute for Global Health and Tropical Medicine, Rockville, MD 20850, USA
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland 20892-2220, USA
| | - S.I. Hay
- Institute for Health Metrics and Evaluation, 2301 Fifth Ave., Suite 600, Seattle, WA 98121, USA
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland 20892-2220, USA
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - R.E. Cibulskis
- Global Malaria Programme, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland
| | - P.W. Gething
- Spatial Ecology and Epidemiology Group, Tinbergen Building, Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
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Abílio AP, Marrune P, de Deus N, Mbofana F, Muianga P, Kampango A. Bio-efficacy of new long-lasting insecticide-treated bed nets against Anopheles funestus and Anopheles gambiae from central and northern Mozambique. Malar J 2015; 14:352. [PMID: 26377825 PMCID: PMC4574012 DOI: 10.1186/s12936-015-0885-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 09/03/2015] [Indexed: 11/10/2022] Open
Abstract
Background Long-lasting insecticide-treated nets (LLINs) are one of the main methods used for controlling malaria transmission in Mozambique. The proliferation of several types of LLINs and the re-emergence of insecticide resistance in the local vector populations poses challenges to the local malaria control programme on selecting suitable insecticide-based vector control products. Therefore, this study evaluated the insecticide susceptibility and bio-efficacy of selected new LLINs against wild populations of Anopheles funestus sensu lato and A. gambiae s.l. from Northern and Central Mozambique. The study also investigated whether the insecticide contents on the LINNs fabrics were within the WHOPES recommended target range. Methods The susceptibility of 2–5 day old wild female A. funestus and A. gambiae sensu stricto against the major classes of insecticides used for vector control, viz: deltamethrin (0.05 %), permethrin (0.75 %), propoxur (0.1 %), bendiocarb (0.1 %) and DDT (4 %), was determined using WHO cylinder susceptibility tests. WHO cone bioassays were conducted to determine the bio-efficacy of both pyrethroid–only LLINs (Olyset®, Permanet 2.0®, NetProtect® and Interceptor®) and, Permanet 3.0® a combination LLIN against A. funestus s.s, from Balama, Mocuba and Milange districts, respectively. The bio-efficacy of LLINs against the insectary-susceptible A. arabiensis (Durban strain) was assessed, as well. Untreated bed net swatches were used as negative controls. Chemical analyses, by high performance liquid chromatography, were undertaken to assess whether the insecticide contents on the LLINs fabrics fell within recommended target dose ranges. The frequency of kdr gene mutations was determined from a random sample of A. gambiaes.s. from both WHO susceptibility and cone bioassay experiments. Results Anopheles funestus from Balama district showed resistance to deltamethrin and possible resistance to permethrin, propoxur and bendiocarb, whilst A. gambiae from Mocuba district was susceptible to deltamethrin, bendiocarb and propoxur. There were no kdr mutants found in the sample of 256 A. gambiae tested. Overall, 186 LLIN swatches were tested. Mosquitoes exposed to Olyset® had the lowest knockdown (±standard error) and mortality rate (±standard error) in all studied sites regardless of vectors species tested. Permanet 3.0 showed the highest bio-efficacy independent of vector species tested and level of insecticide resistance detected. All types of LLINs effectively killed susceptible A. arabiensis Durban strain. The insecticide content of Olyset® and Permanet 2.0® was higher than the target dose but NetProtect® had a lower insecticide content than the target dose. Conclusion The study shows evidence of considerable heterogeneity in both insecticide susceptibility and the level of bio-efficacy of commonly available types of LLINs against wild A. funestus and A. gambiae from Balama, Mocuba and Milange districts, located in north and centre of Mozambique. The findings suggest that vector control approaches combining different types of insecticides might help to tackle the apparent problem of pyrethroid resistance in the vector populations from these three sites. Results from bioassays on laboratory-susceptible A. arabiensis strongly suggest that LLINs can offer some protection against susceptible malaria vectors. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0885-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ana Paula Abílio
- Laboratório de Entomologia, Instituto Nacional de Saúde (INS), Av. Eduardo Mondlane/Salvador Allende, no 1008, C.P. 246, Maputo, Mozambique.
| | - Pelágio Marrune
- Programa Nacional de Controlo da Malária (PNCM), Direcção Provincial de Saúde de Cabo Delgado, Cabo Delgado Province, Mozambique.
| | - Nilsa de Deus
- Departamento de Pesquisa, Instituto Nacional de Saúde (INS), Av. Eduardo Mondlane/Salvador Allende, no 1008, C.P. 246, Maputo, Mozambique.
| | - Francisco Mbofana
- Direcção Nacional de Saúde Pública (DNSP), Av. Eduardo Mondlane/Salvador Allende, no 1008, C.P. 246, Maputo, Mozambique.
| | - Pedro Muianga
- Abt Associates Inc/AIRS, Zambezia Province, Mozambique.
| | - Ayubo Kampango
- Laboratório de Entomologia, Instituto Nacional de Saúde (INS), Av. Eduardo Mondlane/Salvador Allende, no 1008, C.P. 246, Maputo, Mozambique.
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Noor AM. Measurement of the subnational effect of vector control interventions on malaria infection. LANCET GLOBAL HEALTH 2014; 2:e559-60. [PMID: 25304625 DOI: 10.1016/s2214-109x(14)70205-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Abdisalan M Noor
- Spatial Health Metrics Group, Department of Public Health Research, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
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