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 interepidemic,
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%); 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 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
bacteria 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.
