Tick-borne pathogens, including Crimean-Congo haemorrhagic fever virus,
at livestock markets and slaughterhouses in western Kenya
Abstract
Vectors of emerging infectious diseases have expanded their
distributional ranges in recent decades due to increased global travel,
trade connectivity, and climate change. Transboundary range shifts,
arising from the continuous movement of humans and livestock across
borders, are of particular disease control concern. Several tick-borne
diseases are known to circulate between eastern Uganda and the western
counties of Kenya, with one fatal case of Crimean-Congo haemorrhagic
fever (CCHF) reported in 2000 in Western Kenya. Recent reports of CCHF
in Uganda have highlighted the risk of cross-border disease translocation
and the importance of establishing inter-epidemic, early warning systems
to detect possible outbreaks. We therefore carried out surveillance of
tick-borne zoonotic pathogens at livestock markets and slaughterhouses
in three counties of western Kenya that neighbour Uganda. Ticks and
other ectoparasites were collected from livestock and identified using
morphological keys. The two most frequently sampled tick species were
Rhipicephalus decoloratus (35%) and Amblyomma variegatum (30%), and
Ctenocephalides felis fleas and Haematopinus suis lice were also present. In total
486 ticks, lice, and fleas were screened for pathogen presence using
established molecular workflows incorporating high-resolution melting
analysis and identified through PCR-sequencing of PCR products. We
detected CCHF virus in Rh. decoloratus and Rhipicephalus sp. cattle
ticks and 82 of 96 pools of Am. variegatum were positive for Rickettsia
africae. Apicomplexan protozoa and bcteria of veterinary importance,
such as Theileria parva, Babesia bigemina, and Anaplasma marginale, were
primarily detected in rhipicephaline ticks. Our findings show the
presence of several pathogens of public health and veterinary importance
in ticks from livestock at livestock markets and slaughterhouses in western Kenya. Confirmation of CCHF virus, a Nairovirus that causes
haemorrhagic fever with a high case fatality rate in humans, highlights
the risk of under-diagnosed zoonotic diseases and calls for continuous surveillance and the development of preventative measures.