Molecular Detection of Selected Haemopathogens in Domestic Animals and Their Associated Ectoparasitic Biting Keds (Genus Hippobosca) Collected from Laisamis, northern Kenya

Abstract

Production of domestic animals plays a central role to the livelihood of pastoralists inhabiting marginalized arid and semi-arid regions of northern Kenya. Pastoralists rely on their domestic animals such as goat, cattle and sheep for nutrition, through milk and meat production and income through sale of animal products. However, production of domestic animals is limited by pests and diseases. Hippoboscids (keds) and ticks are the predominant blood-feeding ectoparasites of domestic animals in northern Kenya. Therefore, the aim of this study was to identify hippoboscids infesting various domestic animals (goat, sheep, donkey, and dog) in Laisamis, Marsabit County, northern Kenya, and detect haemopathogens (Trypanosoma spp., Anaplasma spp., Ehrlichia spp., Theileria spp., Babesia spp., Clostridium perfringens, and Brucella spp.) in both the domestic animals and their associated ectoparasitic biting keds. The field study research design was cross-sectional, and domestic animals including goats, sheep, donkeys, and dogs, and their ectoparasitic hippoboscids were sampled for collection. Fresh blood (n = 389) from the animals were stored in EDTA vacutainers tubes and preserved immediately in liquid nitrogen while hippoboscids (n = 235) were preserved in absolute ethanol and transported to icipe laboratories in Kasarani for screening of pathogens. Genomic DNA was extracted from whole hippoboscids and blood samples, and PCR-HRMA (High Resolution Melt Analysis) performed for detection of pathogens by comparison of HRMA profiles of the test samples with the known positive controls. DNA sequencing of samples with unique HRM profiles then followed to confirm the specific species of the pathogens. Geneious Prime software was used in analysis of the sequences. Morphological examination, confirmed through gene sequencing, revealed two hippoboscid species: Hippobosca variegata and Hippobosca longipennis). Among the pathogens detected in goats included: Anaplasma ovis (84.5%), a novel Anaplasma sp. (11.8%), Trypanosoma vivax (7.3%), Ehrlichia canis (66.1%), and Theileria ovis (0.8%). Similarly, A. ovis (93.5%), E. canis (22.2%), and T. ovis (38.9%) were detected in sheep. Donkeys, were positive for ‘Candidatus Anaplasma camelii’ (11.1%), T. vivax (22.2%), E. canis (25%), and Theileria equi (13.9%). In addition, keds carried the following pathogens; goat/sheep keds - T. vivax (29.3%), Trypanosoma evansi (0.86%), Trypanosoma godfreyi (0.86%), and E. canis (51.7%); donkey keds - T. vivax (18.2%) and E. canis (63.6%); and; dog keds - T. vivax (15.7%), T. evansi (0.9%), Trypanosoma simiae (0.9%), E. canis (76%), Clostridium perfringens (46.3%), Bartonella schoenbuchensis (76%), and Brucella abortus (5.6%). Dog keds harboured the most pathogens, suggesting dogs as the key reservoirs of pathogens in the study area. Pathogens such as Trypanosoma vivax and Ehrlichia canis were detected in both the blood and hippoboscids collected from the domesticated animals, suggesting the potential utility of hippoboscids in xenosurveillance of pathogens in their associated hosts. The presence of zoonotic pathogens such as Brucella abortus, in domestic animals of the study area calls for an urgent need for further surveillance of pathogens circulating in Kenyan domestic animals, and establish the possible role of keds in disease transmission. Information from this study will guide the policy makers and livestock farmers in disease control and management.