Tsetse blood-meal sources, endosymbionts, and trypanosome infections provide insight into African trypanosomiasis transmission in the Maasai Mara National Reserve, a wildlife-human-livestock interface

Abstract

36 Background: African trypanosomiasis (AT) is a neglected disease of both humans and animals 37 caused by Trypanosoma parasites, which are transmitted by obligate hematophagous tsetse flies 38 (Glossina spp.). Understanding of AT transmission is hampered by limited knowledge on 39 interactions of tsetse flies with their vertebrate hosts and the influence of endosymbionts on 40 vector competence, especially in wildlife-human-livestock interfaces. We identified the tsetse 41 species, their blood-meal sources, and the correlation between endosymbiont and trypanosome 42 infection status in the trypanosome-endemic Maasai Mara National Reserve (MMNR) of Kenya.3 43 Methodology/Principal Findings: Among 1167 tsetse flies (1136 Glossina pallidipes, 31 44 Glossina swynnertoni) collected from 10 sampling sites, 28 (2.4%) were positive by PCR for 45 trypanosomes, majority (17/28) being Trypanosoma vivax. Blood-meal analyses based on high-46 resolution melting analysis of mitochondrial cytochrome c oxidase 1 and cytochrome b gene 47 PCR products (n = 345) identified humans as the most common vertebrate host (37%), followed 48 by hippopotamus (29.1%), African buffalo (26.3%), elephant (3.39%) , and giraffe (0.84%).49 Trypanosome-infected flies had fed on hippopotamus and buffalo. Additionally, PCR analysis 50 revealed that tsetse flies were more likely to be infected with trypanosomes if they were infected 51 with the Sodalis glossinidius endosymbiont (P = 0.0022 Fisher's exact test).52 Conclusions/Significance: Diverse species of wildlife hosts may contribute to the maintenance 53 of tsetse populations and/or persistent circulation of African trypanosomes in the MMNR.54 Although the African buffalo is known to be a key reservoir of AT, the higher proportion of 55 hippopotamus blood-meals in trypanosomes-infected flies identified here indicates that other 56 wildlife species may also be important to transmission cycles. No trypanosomes associated with 57 human disease were identified, but the high proportion of human blood-meals identified are 58 indicative of human African trypanosomiasis transmission risk. Furthermore, this work provides 59 data showing that Sodalis endosymbionts can is associated with increased trypanosome infection 60 rates in endemic ecologies. 61Author summary 62 Human and animal African trypanosomiasis are neglected tropical diseases with potential to 63 spread to new areas. Wild animals are important reservoirs for African trypanosomes and crucial 64 in the emergence and re-emergence of AT. Vertebrate host-vector-parasite interactions are 65 integral to trypanosome transmission. We investigated the vertebrate blood-meals and 4 66 trypanosomes-endosymbionts co-infections in tsetse flies, which have been associated with 67 reservoirs and vector competence, respectively, on AT transmission in Kenya's Maasai Mara 68 National Reserve. We identified tsetse fly diversity, trypanosome and endosymbiont infection 69 status, and vertebrate blood-meal hosts to infer potential transmission dynamics. We found 70...

Prevalence of Trypanosoma and Sodalis in wild populations of tsetse flies and their impact on sterile insect technique programmes for tsetse eradication

“… 30 . Furthermore, in the wildlife-livestock-human interface in the Maasai Mara National Reserve in Kenya, it was shown that G. pallidipes infected with Sodalis was associated with increased Trypanosoma infection rates 31 . However, other studies have found no strong association between trypanosome and Sodalis in some tsetse species collected in four locations in Kenya 32 .…”

Biopesticide Research and Product Development in Africa for Sustainable Agriculture and Food Security – Experiences From the International Centre of Insect Physiology and Ecology (icipe)

“…Analysis of blood meals from wildlife in Masai Mara, Kenya has revealed the prevalence of the insect symbionts Sodalis glossinidius and Coxiella sp. in tsetse flies and ticks, respectively (Makhulu et al, 2020;Oundo et al, 2020). Distinct strains of endosymbiotic Spiroplasma sp.…”

Prevalence of Trypanosoma and Sodalis in Wild Populations of Tsetse Flies: Impact on Sit Programmes for Tsetse Eradication

“…30 . Furthermore, in the wildlife-livestock-human interface in the Maasai Mara National Reserve in Kenya, it was shown that Glossina pallidipes infected with Sodalis was associated with increased Trypanosoma infection rates 31 . However, other studies have found no strong association between trypanosome and Sodalis in some tsetse species collected in four locations in Kenya 32 .…”