Spatially aggregated clusters and scattered smaller loci of elevated malaria vector density and human infection prevalence in urban Dar es Salaam, Tanzania

Malaria Journal

Research

Benn K. D. Sartorius¹  Yeromin P. Mlacha²  John M. Paliga²  Alex J. Limwagu²  Zawadi D. Mageni²  Nicodem J. Govella²  Daniel F. Msellemu²  Gerry F. Killeen³  Stefan Dongus⁴  Victoria M. Mwakalinga⁵  Maureen Coetzee⁶ 

[1] Discipline of Public Health Medicine, School of Nursing and Public Health, University of KwaZulu-Natal, Durban, South Africa;Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, P.O. Box 78373, Coordination Office, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania;Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, P.O. Box 78373, Coordination Office, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania;Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK;Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, P.O. Box 78373, Coordination Office, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania;Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK;Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box, 4002, Basel, Switzerland;University of Basel, 4001, Basel, Switzerland;School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa;Department of Housing and Infrastructure Planning, School of Urban and Regional Planning, Ardhi University, P.O. Box 35176, Dar es Salaam, United Republic of Tanzania;Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, P.O. Box 78373, Coordination Office, Kiko Avenue, Mikocheni, Dar es Salaam, United Republic of Tanzania;Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa;

关键词: Hotspots;    Spatial clustering;    Mapping;    Plasmodium falciparum;    Malaria;    Anopheles gambiae;    Mosquito;   

DOI  :  10.1186/s12936-016-1186-9

 received in 2015-11-03, accepted in 2016-02-20,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundMalaria transmission, primarily mediated by Anopheles gambiae, persists in Dar es Salaam (DSM) despite high coverage with bed nets, mosquito-proofed housing and larviciding. New or improved vector control strategies are required to eliminate malaria from DSM, but these will only succeed if they are delivered to the minority of locations where residual transmission actually persists. Hotspots of spatially clustered locations with elevated malaria infection prevalence or vector densities were, therefore, mapped across the city in an attempt to provide a basis for targeting supplementary interventions.MethodsTwo phases of a city-wide population-weighted random sample of cross-sectional household surveys of malaria infections were complemented by two matching phases of geographically overlapping, high-resolution, longitudinal vector density surveys; spanning 2010–2013. Spatial autocorrelations were explored using Moran’s I and hotspots were detected using flexible spatial scan statistics.ResultsSeven hotspots of spatially clustered elevated vector density and eight of malaria infection prevalence were detected over both phases. Only a third of vectors were collected in hotspots in phase 1 (30 %) and phase 2 (33 %). Malaria prevalence hotspots accounted for only half of malaria infections detected in phase 1 (55 %) and phase 2 (47 %). Three quarters (76 % in phase 1 and 74 % in phase 2) of survey locations with detectable vector populations were outside of hotspots. Similarly, more than half of locations with higher infection prevalence (>10 %) occurred outside of hotspots (51 % in phase 1 and 54 % in phase 2). Vector proliferation hazard (exposure to An. gambiae) and malaria infection risk were only very loosely associated with each other (Odds ratio (OR) [95 % Confidence Interval (CI)] = 1.56 [0.89, 1.78], P = 0.52)).ConclusionMany small, scattered loci of local malaria transmission were haphazardly scattered across the city, so interventions targeting only currently identifiable spatially aggregated hotspots will have limited impact. Routine, spatially comprehensive, longitudinal entomological and parasitological surveillance systems, with sufficient sensitivity and spatial resolution to detect these scattered loci, are required to eliminate transmission from this typical African city. Intervention packages targeted to both loci and hotspots of transmission will need to suppress local vector proliferation, treat infected residents and provide vulnerable residents with supplementary protective measures against exposure.

【 授权许可】

CC BY   
© Mwakalinga et al. 2016