Molecular prevalence and risk factors associated with tick-borne pathogens in cattle in western Kenya

Tatenda Chiuya,Daniel K Masiga,Maurice K Murungi,Jandouwe Villinger,Lillian Wambua,Dickens O Ondifu,Eric M Fèvre,Armanda D S Bastos,Laura C Falzon

doi:10.1186/s12917-021-03074-7

Abstract

BackgroundTick-borne pathogens (TBPs) are of global importance, especially in sub-Saharan Africa where they represent a major constraint to livestock production. Their association with human disease is also increasingly recognized, signalling their zoonotic importance. It is therefore crucial to investigate TBPs prevalence in livestock populations and the factors associated with their presence. We set out to identify TBPs present in cattle and to determine associated risk factors in western Kenya, where smallholder livestock production is important for subsistence and market-driven income.ResultsTick-borne pathogen infections in blood samples collected from cattle at livestock markets and slaughterhouses between May 2017 and January 2019 were identified by high-resolution melting analysis and sequencing of PCR products of genus-specific primers. Of the 422 cattle sampled, 30.1% (127/422) were infected with at least one TBP, while 8.8% (37/422) had dual infections. Anaplasma spp. (19.7%) were the most prevalent, followed by Theileria (12.3%), Ehrlichia (6.6%), and Babesia (0.2%) spp. Sequence analysis of the TBPs revealed them to be Anaplasma platys-like organisms (13.5%), Theileria velifera (7.4%), Anaplasma marginale (4.9%), Theileria mutans (3.1%), Theileria parva (1.6%), and Babesia bigemina (0.2%). Ehrlichia ruminantium, Rickettsia spp., and arboviruses were not detected. Exotic breeds of cattle were more likely to be infected with A. marginale compared to local breeds (OR: 7.99, 95% CI: 3.04–22.02, p < 0.001). Presence of ticks was a significant predictor for Anaplasma spp. (OR: 2.18, 95% CI: 1.32–3.69, p = 0.003) and Ehrlichia spp. (OR: 2.79, 95% CI: 1.22–7.23, p = 0.022) infection. Cattle sampled at slaughterhouses were more likely to be positive for Anaplasma spp. (OR: 1.64, 95% CI: 1.01–2.70, p = 0.048) and A. marginale (OR: 3.84, 95% CI: 1.43–12.21, p = 0.012), compared to those sampled at livestock markets.ConclusionThis study reports TBP prevalence and associated risk factors in western Kenya, factors which are key to informing surveillance and control measures.

Highlights

Tick-borne pathogens (TBPs) are of global importance, especially in sub-Saharan Africa where they represent a major constraint to livestock production
Exotic breeds of cattle were significantly more likely to be infected with A. marginale (OR: 7.99, 95% Confidence interval (CI): 3.04–22.02, p < 0.001), and less likely to be infected with Theileria spp. (OR: 0.20, 95% CI: 0.03–0.67, p = 0.023), compared to local breeds
The natural resistance of local breeds to Tick-borne disease (TBD), the importance of tick control, and the potential for Livestock market (LM) and SHs to serve as surveillance points for TBPs are highlighted in our logistic regression analysis where exotic breeds, tick presence and sampling at SHs were associated with the occurrence of TBPs

Summary

Introduction

Tick-borne pathogens (TBPs) are of global importance, especially in sub-Saharan Africa where they represent a major constraint to livestock production. Their association with human disease is increasingly recognized, signalling their zoonotic importance. In Kenya, the Chiuya et al BMC Veterinary Research (2021) 17:363 commonly reported tick-borne diseases (TBDs) associated with livestock production constraints include East Coast fever (Theileria parva: Rhipicephalus appendiculatus), babesiosis (Babesia bigemina: Rhipicephalus decoloratus), anaplasmosis (Anaplasma marginale: Rhipicephalus decoloratus), and heartwater (Ehrlichia ruminantium: Amblyomma variegatum) [3,4,5,6]. Other benign Theileria spp., such as Theileria taurotragi, Theileria mutans, and Theileria velifera, are highly prevalent [7] Due to their endemic stability in the predominantly indigenous cattle herds in Kenya, most of these TBDs are clinically inapparent. Pregnancy or co-infection with other pathogens may compromise the natural resistance in indigenous cattle, leading to disease manifestation, including weight loss, a drop in milk production, and mortalities [9, 10]

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Conclusion