Abstract
Background: Changes in climate and land use can alter risk of transmission of parasites between domestic hosts and wildlife, particularly when mediated by vectors that can travel between populations. Here we focused on tsetse flies (genus Glossina), the cyclical vectors for both Human African Trypanosomiasis (HAT) and Animal African Trypanosomiasis (AAT). The aims of this study were to investigate three issues related to G. palldipes from Kenya: 1) the diversity of vertebrate hosts that flies fed on; 2) whether host feeding patterns varied in relation to type of hosts, tsetse feeding behaviour, site or tsetse age and sex; and 3) if there was a relationship between trypanosome detection and host feeding behaviours or host types. Methods: Sources of blood meals of Glossina pallidipes were identified by sequencing of the mitochondrial cytochrome b gene and analyzed in relationship with previously determined trypanosome detection in the same flies. Results: In an area dominated by wildlife but with seasonal presence of livestock (Nguruman), 98% of tsetse fed on single wild host species, whereas in an area including a mixture of resident domesticated animals, humans and wildlife (Shimba Hills), 52% of flies fed on more than one host species. Multiple Correspondence Analysis revealed strong correlations between feeding pattern, host type and site but these were resolved along a different dimension than trypanosome status, sex and age of the flies. Conclusions: Our results suggest that individual G. pallidipes in interface areas may show higher feeding success on wild hosts when available but often feed on both wild and domesticated hosts. This illustrates the importance of G. pallidipes as a vector connecting the sylvatic and domestic cycles of African trypanosomes.
Highlights
In sub-Saharan Africa, changes in land use increase encroachment of domestic livestock into areas that are primarily managed to conserve wildlife
Diversity of hosts identified from G. pallidipes blood meals From 573 G. pallidipes, 128 flies showed no evidence of a recent blood meal based on lack of amplification products following the screening with the Cb1 and Cb2 primers
Previous studies have found a similar diversity of hosts as we found based on analyses using the same cytochrome b primers[44] or other mtDNA regions[27], we are not aware of other studies that differentiated single from multiple feeding based on analysis of sequence chromatograms
Summary
In sub-Saharan Africa, changes in land use increase encroachment of domestic livestock into areas that are primarily managed to conserve wildlife This increases risks that livestock will be exposed to a wider range of parasites, with potentially important consequences for disease burden and control. Domesticated animals infected by wildlife pathogens could in turn show more severe disease, given limited opportunity for host-pathogen coevolution in novel hosts This could be true for vector-mediated transmission, where movement of the vectors could facilitate parasite sharing across interface areas, even if fences are used to reduce contact between domestic and wild hosts. There are multiple species of tsetse flies that can transmit multiple species of trypanosomes, Glossina pallidipes is the most economically important species in East Africa[3], because it is the main vector of Animal African Tryanosomiasis (AAT) and it is a vector of Human African Trypanosomiasis (HAT).
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