Abstract
BackgroundEnvironmental disturbance, deforestation and socioeconomic factors all affect malaria incidence in tropical and subtropical endemic areas. Deforestation is the major driver of habitat loss and fragmentation, which frequently leads to shifts in the composition, abundance and spatial distribution of vector species. The goals of the present study were to: (i) identify anophelines found naturally infected with Plasmodium; (ii) measure the effects of landscape on the number of Nyssorhynchus darlingi, presence of Plasmodium-infected Anophelinae, human biting rate (HBR) and malaria cases; and (iii) determine the frequency and peak biting time of Plasmodium-infected mosquitoes and Ny. darlingi.MethodsAnopheline mosquitoes were collected in peridomestic and forest edge habitats in seven municipalities in four Amazon Brazilian states. Females were identified to species and tested for Plasmodium by real-time PCR. Negative binomial regression was used to measure any association between deforestation and number of Ny. darlingi, number of Plasmodium-infected Anophelinae, HBR and malaria. Peak biting time of Ny. darlingi and Plasmodium-infected Anophelinae were determined in the 12-h collections. Binomial logistic regression measured the association between presence of Plasmodium-infected Anophelinae and landscape metrics and malaria cases.ResultsNinety-one females of Ny. darlingi, Ny. rangeli, Ny. benarrochi B and Ny. konderi B were found to be infected with Plasmodium. Analysis showed that the number of malaria cases and the number of Plasmodium-infected Anophelinae were more prevalent in sites with higher edge density and intermediate forest cover (30–70%). The distance of the drainage network to a dwelling was inversely correlated to malaria risk. The peak biting time of Plasmodium-infected Anophelinae was 00:00–03:00 h. The presence of Plasmodium-infected mosquitoes was higher in landscapes with > 13 malaria cases.ConclusionsNyssorhynchus darlingi, Ny. rangeli, Ny. benarrochi B and Ny. konderi B can be involved in malaria transmission in rural settlements. The highest fraction of Plasmodium-infected Anophelinae was caught from midnight to 03:00 h. In some Amazonian localities, the highest exposure to infectious bites occurs when residents are sleeping, but transmission can occur throughout the night. Forest fragmentation favors increases in both malaria and the occurrence of Plasmodium-infected mosquitoes in peridomestic habitat. The use of insecticide-impregnated mosquito nets can decrease human exposure to infectious Anophelinae and malaria transmission.Graphical
Highlights
Environmental disturbance, deforestation and socioeconomic factors all affect malaria incidence in tropical and subtropical endemic areas
Malaria hotspots occurr in the Brazilian Amazon where both P. vivax and P. falciparum transmission is continuously high [8]. Such hotspots represent a challenge in terms of achieving the control and elimination of Plasmodium infection [9]. Some of these hotspots are found in the westernmost municipalities of Cruzeiro do Sul and Mâncio Lima (Acre state), where the proportion of malaria cases due to P. falciparum and P. vivax + P. falciparum can be as high as 25% of the overall estimated cases in Acre [7]
The results of the analyses showed a negative association between the distance of the household to the nearest water drainage network (DW) and the presence and number of Plasmodiuminfected anophelines in the peridomestic habitat, including Ny. darlingi
Summary
Environmental disturbance, deforestation and socioeconomic factors all affect malaria incidence in tropical and subtropical endemic areas. Malaria hotspots occurr in the Brazilian Amazon where both P. vivax and P. falciparum transmission is continuously high [8]. Such hotspots represent a challenge in terms of achieving the control and elimination of Plasmodium infection [9]. Some of these hotspots are found in the westernmost municipalities of Cruzeiro do Sul and Mâncio Lima (Acre state), where the proportion of malaria cases due to P. falciparum and P. vivax + P. falciparum can be as high as 25% of the overall estimated cases in Acre [7]
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