Molecular characterisation of tick-borne pathogens in cattle in Kenya : insights from blood, ticks, and skin swab analyses

Abstract

BACKGROUND : Ticks pose a major threat to livestock and human health in sub-Saharan Africa, with climate change and pastoral movements fueling their spread. Few studies have integrated multiple sample types to characterize tick-borne pathogens (TBPs) in cattle in Kenya. This knowledge gap hinders the development of effective surveillance and control strategies, leaving vulnerable populations and their livestock susceptible to these persistent threats. METHODS : We screened 280 bovine blood samples, 589 tick pools, and 284 non-invasive skin swabs from cattle in northern (Marsabit) and southern (Kajiado) Kenya by high-resolution melting analysis and Sanger sequencing of PCR products. RESULTS : Rhipicephalus spp. (47.1%), Hyalomma spp. (30.8%), and Amblyomma spp. (22.1%) were prevalent, with Rhipicephalus evertsi only found in Kajiado and Rhipicephalus camicasi in Marsabit. In blood, Anaplasma spp. (62.9%; A. marginale, A. platys, A. ovis) and Theileria spp. (34.6%; T. velifera, T. mutans) were dominant. Tick pools harbored Coxiella burnetii, Rickettsia africae, Rickettsia aeschlimannii, Anaplasma marginale, Theileria velifera, T. ovis, and Babesia occultans, and for the first time two co-circulating Ehrlichia ruminantium strains (Welgevonden and Kumm2). Notably, C. burnetii and T. ovis were detected only in Marsabit, and T. mutans only in Kajiado. Skin swabs from tick predilection sites (ears, anal region) yielded R. africae, R. aeschlimannii, and T. velifera at low positivity, while nose swabs were negative. CONCLUSIONS : Detection of zoonotic pathogens such as C. burnetii and R. africae underscores critical public health risks, and co-infections in cattle reinforce the need for robust, integrated surveillance. Although skin swabs demonstrated limited diagnostic yield, they remain a promising non-invasive sampling approach. These findings highlight the value of targeted acarological research and coordinated control programs under a One Health framework.