M411 Lecture: Kevin Njabo, PhD "Vectors of Avian Malaria in Africa and their blood feeding habits"

November 1, 2012 - 12:00pm - 1:00pm

Location

Lecture Hall 43-105 CHS
United States

Malaria parasites use vertebrate hosts for asexual multiplication and Culicidae mosquitoes for sexual and asexual development, yet the literature on avian malaria remains biased towards examining the asexual stages of the life cycle in birds. To fully understand parasite evolution and mechanism of malaria transmission, knowledge of all three components of the vector-host-parasite system is essential. Little is known about avian parasite-vector associations in African rainforests where numerous species of birds are infected with avian haemosporidians of the genera Plasmodium and Haemoproteus. Secondly, mosquito blood feeding behavior is a very significant component of pathogen transmission and determinant of disease epidemiology. Yet, knowledge of foraging ecology of mosquitoes often depends on the presence of undigested blood in the mosquito midgut. Approximately 36 hours after feeding, the blood meal is sufficiently digested to make identification by molecular techniques difficult leaving a very narrow window in which these methods can be used. In our study, we apply high resolution melt qPCR-based techniques and nested PCR to examine the occurrence and diversity of mitochondrial cytochrome b gene sequences of haemosporidian parasites in wild-caught mosquitoes sampled across 12 sites in Cameroon. We also investigate the feeding habits of these mosquitoes from four genera based on the isotopic ratios of nitrogen (δ15N), carbon (δ13C) and sulphur (δ34S). In all, we screened 3134 mosquitoes representing 27 species. Four genera were infected with twenty-two parasite lineages (18 Plasmodium spp. and 4 Haemoproteus spp.). Presence of Plasmodium sporozoites in salivary glands of Coquillettidia aurites further established these mosquitoes as likely vectors. Unfed mosquitoes were also found to have a lower δ13C, δ15N and middle δ34S values than fed mosquitoes with. δ13C appearing to be the best element to differentiate between mosquito species that fed on different host species. Isotopic analyses show that the different mosquito genera may be separated based on their diets, suggesting that linking stable isotope-based assays and DNA analysis may be a powerful new tool to investigate mosquito feeding ecology and the dynamics of vector-borne pathogens.

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