Prevalence and transmission of selected infectious disease-causing enzootic and zoonotic pathogens by haematophagous camel keds, Hippobosca camelina, in Laisamis, Marsabit county of northern Kenya

Abstract

Hippobosca camelina, also known as camel keds or camel louse flies, are the most common blood-sucking ectoparasites infesting camels in, Laisamis Ward, northern Kenya. The ability of these obligate haematophagous biting flies to transmit infectious agents is less understood. The aims of this study were to; I) screen for protozoan, bacterial and viral pathogens in camels and their biting keds, H. camelina, sampled from Laisamis Ward, Marsabit county II) assess the potential utility of camel keds in xenosurveillance of camel haemopathogens, and III) study the capacity of camel keds to transmit haemopathogens to experimental mice. Blood samples (n = 249 camels) and camel keds (n = 117) were collected from camels in Laisamis Ward, Marsabit County, Kenya and screened for the presence of trypanosomes, Anaplasma, Ehrlichia, Brucella, Coxiella, camel pox, Theileria, and Babesia species using conventional PCR coupled with high-resolution melting (HRM) of the PCR products generating unique melt curves for each of the pathogens. Keds were also screened for these camel haemopathogens to assess their role in xenodiagnoses by PCR-HRM. The ability of camel keds to transmit infectious agents was determined by exposing naïve mice (Mus musculus) (n = 21, test = 19, control = 2) to freshly collected keds for bloodmeal acquisition through bites. PCR established presence of Trypanosoma vivax and Trypanosoma evansi species in camels at 41% and 1.2%, respectively. Additionally, “Candidatus Anaplasma camelii” (68.7%) and Ehrlichia regneryi (0.4%) were also detected in camels. Similarly, T. vivax (45.3%) and T. evansi (2.56%) also detected in camel keds. Trypanosoma melophagium was detected in one camel ked (1/117) (0.4%), but not in camels. Bacterial pathogen “Candidatus Anaplasma camelii” was detected in 16.2% of the collected camel keds, but. E. regneryi was not detected. Nine mice (9/19, 47.4 %) exposed to feeding bites of camel keds acquired “Candidatus Anaplasma camelii” demonstrating the ability of the keds to transmit Anaplasma to mice. These findings reveal the presence of enzootic (e.g. T. vivax infection) and potentially zoonotic pathogens, including some species of Anaplasma and Ehrlichia in camels from Laisamis Ward, northern Kenya. Additionally, the presence of similar pathogens in camels and in keds collected from sampled camels suggests the role of these keds in their transmission and the potential use of these flies in xenosurveillance of these haemopathogens circulating in camel herds. The findings of this study forms the basis for developing targeted disease control programs.