Genetic connectivity of trypanosomes between tsetse-infested and tsetse-free areas of Kenya

Abstract

The prevalence rates of trypanosomes, including those that require cyclical transmission by tsetse flies, are widely distributed in Africa. Trypanosoma brucei and Trypanosoma congolense are actively maintained in regions where there are no tsetse flies although at low frequencies. Whether this could be due to an independent evolutionary origin or multiple introduction of trypanosomes due to continuous movement of livestock between tsetse-free and -infested areas is not known. Thus, the aim of the study was to carry out microsatellite genotyping to explore intra-specific genetic diversity between T. (Trypanozoon), T. congolense and Trypanosoma vivax from the two regions: tsetse infested and tsetse free. Microsatellite genotyping showed geographical origin-based structuring among T. (Trypanozoon) isolates. There was a clear separation between isolates from the two regions signalling the potential of microsatellite markers as diagnostic markers for T. brucei and Trypanosoma evansi isolates. Trypanosoma vivax isolates also clustered largely based on the sampling location with a significant differentiation between the two locations. However, our results revealed that T. congolense isolates from Northern Kenya are not genetically separated from those from Coastal Kenya. Therefore, these isolates are likely introduced in the region through animal movement. Our results demonstrate the occurrence of both genetic connectivity as well as independent evolutionary origin, depending on the trypanosome species between the two ecologies.

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

“…These biting flies harboured similar trypanosome species as G. pallidipes, one of the major tsetse species in sub-Saharan Africa, due to its wider geographical distribution and economic importance (Getahun et al 2014;Njiru et al 2004a, b;Saini et al 2017). The detection of diverse trypanosomes in non-tsetse infested areas shows that trypanosomes are widely spread across a broad geographic area that includes tsetse-free regions (Kimenyi et al 2021).…”

“…This finding indicates that T. evansi populations could differ in their degree of virulence in camels. This could be suggestive of the presence of different strains of T. evansi as reflected by different virulence degrees to camels that may be due to genetic variation (Kimenyi et al 2021) or host response, that need to be investigated in the future. However, virulence also depends on the immune status of the host, past and recent infection by complex pathogens, as well as the genetic makeup of individual hosts.…”

“…infecting livestock globally. Its wide geographic distribution (Hoare 1972;Auty et al 2015;Aregawi et al 2019), mode of transmission (Desquesnes et al 2013;Kamidi et al 2017), zoonotic potential (Joshi et al 2005;Shah et al 2011), pathogenicity to several domestic animals (Misra et al 1976), high genetic diversity, and variation in virulence (Kamidi et al 2017(Kamidi et al , 2018Kimenyi et al 2021) make it an important parasite. Animal trypanosomosis caused by T. evansi is called surra in camels and is the most lethal disease of camels worldwide (Njiru et al 2004a, b;Kassa et al 2011;Desquesnes et al 2013).…”

Metabolites From Trypanosome-Infected Cattle as Sensitive Biomarkers for Animal Trypanosomosis

“…Trypanosomes are transmitted mainly by tsetse flies and mechanically by other biting flies, and infect a wide range of livestock and wildlife, thereby causing economic losses by inducing mortality, abortion, and morbidity ( Auty et al, 2012 , 2015 ; Shaw et al, 2014 ). While the prevalence of Human African Trypanosomosis (HAT) has reduced in recent years ( Aksoy et al, 2017 ), animal trypanosomosis including zoonotic once, also known as (nagana) remains one of the most significant infectious disease threats to livestock sector, even beyond tsetse fly infested areas ( Jones and Dávila, 2001 ; Garcia et al, 2016 ; Getahun et al, 2020a ; Kimenyi et al, 2021 ). A better understanding of livestock–trypanosome interactions is the key to effectively control trypanosomosis.…”

Entomological assessment of tsetse-borne trypanosome risk in the Shimba Hills human-wildlife-livestock interface, Kenya

“…However, trypanosome epidemiology and transmission risk patterns are largely understudied in Shimba Hills. Although different studies in the area have assessed trypanosome diversity and rates in tsetse flies ( 9 – 11 ), none of these studies extended the entire stretch of the human-wildlife-livestock interface or evaluated infection rates in tsetse flies in relation to vector abundance and cattle bloodmeals to determine entomological inoculation rates of trypanosome infections.…”