Molecular characterization of Coxiella burnetii in livestock species in Isiolo County, Kenya and the associated risks factors for seropositivity

Abstract

Background: Coxiella burnetii is the causative agent of Q fever, a zoonotic infection that poses serious threats to both animal and human health, particularly in the Global South. It infects livestock such as cattle, sheep and goats including wildlife and can lead to both agricultural and economic losses. Methods: A cross-sectional study was conducted to collect blood and serum samples from aborted livestock; 18 Cattle, 22 Sheep, and 72 goats from March 2022 – August 2023.The samples were screened for antibodies against Coxiella burnetii and the nucleic acids for Coxiella respectively. Before the onset of our study, all the three livestock species; goats, cattle and sheep in Kinna ward were first sampled to determine the presence of C. burnetii. A total of 275 collected samples were screened for prior exposure of C. burnetii and its results were used as reference for this study thus referred to as baseline study. Results: A total of 387 samples were analyzed consisting of 112 from the cross-sectional study and 275 from the baseline study to determine the presence of anti C. burnetii antibodies. Our results showed that goats had higher seropositivity 49.65% (71/143, 95%CI: 41.97-57.75) followed by sheep 16.67% (15/90, 95%CI: 10.37-25.69) and cattle 3.25% (5/154, 95%CI: 1.40-7.37). Livestock species with a history of abortion had higher seropositivity of 33.89% (goats 57/62, sheep 4/62, cattle 1/62, 95%CI: 27.38-41.08) compared to non-aborting from the baseline study (goats 15/30, sheep 11/30, cattle 4/30,95%CI: 10.34-19.93). Conditional logistic regression model identified abortion as a significant risk factor, with goats being 26.71 times more likely to abort than cattle, and sheep 3.59 times more likely than cattle. Among the 112 blood samples, 54 constituting 34 goats, 12 cattle and 8 sheep tested positive by qPCR and 16 of these were subjected to Sanger sequencing. Conclusion: Phylogenetic analysis, performed using the maximum likelihood approach, provided insights into the genetic diversity and circulation of C. burnetii strains. Findings from this study will support the development of intervention strategies such as vaccination or biosecurity improvements aimed at reducing abortion rates and economic losses in small ruminant and cattle production systems.