Molecular characterization of pathogenic African trypanosomes in biting flies and camels in surra-endemic areas outside the tsetse fly belt in Kenya

Abstract

African animal trypanosomosis (nagana) is becoming prevalent beyond its traditionally defined geographical boundaries in African tsetse belts. However, knowledge of clinically important trypanosomes and infection rate in non-tsetse hematophagous flies and domestic animals are limited. This study characterized the potential mechanical vectors, their host feeding patterns, and trypanosome infection in them and domestic animals outside the tsetse belt in northern Kenya. Field-trapped flies and blood from camels, cattle, donkeys, goats, and sheep were screened for trypanosome infection by microscopy and polymerase chain reaction (PCR) of the internal transcribed spacer 1 region. Blood-fed specimens were analysed using PCR-HRM and/or sequencing of 16S rRNA gene to identify vertebrate blood-meal host sources. Hippobosca camelina, Stomoxys calcitrans, Tabanus spp., and Pangonia rueppellii were identified as potential vectors of trypanosomes outside the tsetse belt in Marsabit County. The trypanosome species, Trypanosoma vivax, T. evansi, T. brucei, and T. congolense were recovered in biting flies as well as in camels (Camelus dromedarius). The diversity of parasites in the biting flies was similar to that detected in the tsetse fly Glossina pallidipes collected from the tsetse-infested Shimba Hills, in coastal Kenya, suggesting a wide geographic distribution of the trypanosomes in Kenya. The biting flies fed on camels, cattle, goats, and sheep. Furthermore, we identified diverse clinical outcomes based on PCV (anemia), heamorrhagia) associated with infection with disparate Trypanosoma species. Thus, infection of flies and camels by diverse Trypanosoma species could contribute to the complex epidemiology of observed trypanosomosis in camels.

Biting Flies and Associated Pathogens in Camels in Amibara District of Afar Region, Ethiopia

“…The overall parasitological prevalence of Trypanosoma evansi in the current study area was 7.3%. This result was highly in agreement with the findings in [ 50 ], which reported 7.2% prevalence by using thin blood smears. The higher seroprevalence compared to the parasitological result recorded in the current study could be due to the fact that demonstration of trypanosomes in blood is quite unreliable because a large proportion of infections in the field (50 to 80%) do not develop detectable levels of parasitemia [ 57 ].…”

“…Trypanosome morphological identification in the current study showed that the amount of parasitemia varied from a few parasites per slide to over five t rypanosomes per field of view of the microscope. These findings coincide with the finding of the authors in [ 50 ]. The overall parasitological prevalence of Trypanosoma evansi in the current study area was 7.3%.…”

Spatial–Temporal Variations in Parasitological Prevalence and Host-Related Risk Factors of Camel Trypanosomiasis and Its Vectors in North Eastern Kenya: A Repeated Cross-Sectional Study

“…Limited species diversity was observed in both the rainy and the dry season, perhaps due to the hot and dry environmental conditions in the study area. Comparable fly diversity has been previously recorded in Marsabit county [44]. In contrast, a wider diversity of fly species is generally reported in forested areas [45].…”

“…Therefore, their reduced flight ability may contribute to their inability to fly into the sampling traps. The camel has been shown to provide up to 60% of H. camelina bloodmeals [44] and is thus an important potential vector for T. evansi. In the present study, two species identified, viz., Tabanus taeniola and A. agrestis, comprised the largest proportion of the biting flies captured.…”

Multi-omics analyses reveal rumen microbes and secondary metabolites that are unique to livestock species

“…For instance, camels and small ruminants, to some extent, are the most resilient to frequent drought among the analyzed livestock compared to cattle ( 7 – 10 ). This could be due to the abundant presence of unique anaerobic fungi, Oontomyces , originally identified from Indian camel, ( 46 ) and bacteria ( Prevotella ) in camels that have demonstrated high capability of diet conversion ( 23 , 24 , 39 , 47 ). Additionally, the fungus Neocallimastix, which is present in camels, sheep, and goats but absent in cattle, has been shown to be effective in the bioconversion of poor diet such as lignocellulose into useful products ( 25 , 48 ), which may have contributed to their resilience.…”