Small-scale land-use variability affects Anopheles spp. distribution and concomitant Plasmodium infection in humans and mosquito vectors in southeastern Madagascar

• Type of Material: Article
• Authors: Sarah Zohdy, Emory University; Kristin Derfus, Emory University; Emily G. Headrick, Emory University; Mbolatiana Tovo Andrianjafy, University of Antananarivo; Patricia C. Wright, Stony Brook University; Thomas Gillespie, Emory University
• Language: English
• Date: 2016-02-24
• Publisher: BioMed Central
• Publication Version: Final Published Version
• Copyright Statement: © 2016 Zohdy et al. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1186/s12936-016-1164-2
• Title of Journal or Parent Work: Malaria Journal
• ISSN: 1475-2875
• Volume: 15
• Issue: 1
• Grant/Funding Information: This research was supported by the Jim and Robin Herrnstein Foundation, the Emory University Global Health Institute, the Center for Disease Control and Prevention Malaria Research and Reference Reagent and Resource Center (MR4), and NIH/NIGMS IRACD Grant K12 GM000680.
• Keywords: Ifanadiana District; Plasmodiumvivax; Bed net; Disturbance ecology; Plasmodiumfalciparum
• Research Categories: Health Sciences, Public Health; Environmental Sciences; Biology, Ecology

Abstract

Background: Deforestation and land-use change have the potential to alter human exposure to malaria. A large percentage of Madagascar's original forest cover has been lost to slash-and-burn agriculture, and malaria is one of the top causes of mortality on the island. In this study, the influence of land-use on the distribution of Plasmodium vectors and concomitant Plasmodium infection in humans and mosquito vectors was examined in the southeastern rainforests of Madagascar. Methods: From June to August 2013, health assessments were conducted on individuals living in sixty randomly selected households in six villages bordering Ranomafana National Park. Humans were screened for malaria using species-specific rapid diagnostic tests (RDTs), and surveyed about insecticide-treated bed net (ITN) usage. Concurrently, mosquitoes were captured in villages and associated forest and agricultural sites. All captured female Anopheline mosquitoes were screened for Plasmodium spp. using a circumsporozoite enzyme-linked immunosorbent assay (csELISA). Results: Anopheles spp. dominated the mosquito communities of agricultural and village land-use sites, accounting for 41.4 and 31.4 % of mosquitoes captured respectively, whereas Anopheles spp. accounted for only 1.6 % of mosquitoes captured from forest sites. Interestingly, most Anopheles spp. (67.7 %) were captured in agricultural sites in close proximity to animal pens, and 90.8 % of Anopheles mosquitoes captured in agricultural sites were known vectors of malaria. Three Anopheline mosquitoes (0.7 %) were positive for malaria (Plasmodium vivax-210) and all positive mosquitoes were collected from agricultural or village land-use sites. Ten humans (3.7 %) tested were positive for P. falciparum, and 23.3 % of those surveyed reported never sleeping under ITNs. Conclusions: This study presents the first report of malaria surveillance in humans and the environment in southeastern Madagascar. These findings suggest that even during the winter, malaria species are present in both humans and mosquitoes; with P. falciparum found in humans, and evidence of P. vivax-210 in mosquito vectors. The presence of P. vivax in resident vectors, but not humans may relate to the high incidence of humans lacking the Duffy protein. The majority of mosquito vectors were found in agricultural land-use sites, in particular near livestock pens. These findings have the potential to inform and improve targeted malaria control and prevention strategies in the region.