Sero-epidemiology of Coxiella burnetii in livestock and humans in Isiolo county Kenya

Mutisya, W.M., Akoko, J.M., Mwatondo, A., Muturi, M., Nthiwa, D., Abkallo, H.M., Nyamota, R., Wachira, T., Gathura, P. and Bett, B. 2025. Sero-epidemiology of Coxiella burnetii in livestock and humans in Isiolo county Kenya. PLOS Neglected Tropical Diseases 19(10): e0013557.

Background: Coxiella burnetii, the causative agent of Q fever, is a globally distributed pathogen with significant zoonotic and economic impacts, particularly in regions where humans and livestock interact closely. Although endemic in many countries, including Kenya, comprehensive epidemiological data on the pathogen are limited. To address this gap, we conducted a linked human and livestock populations study in Garbatulla, Isiolo County to assess seroprevalence and identify potential predictors of C. burnetii exposure.

Methods: We used a cross-sectional design with multistage sampling. Blood and serum samples were collected from 2,157 livestock and 683 humans that were recruited from 242 households. Additional data on herd/household and subject characteristics were collected using a structured questionnaire. Indirect enzyme-linked immunosorbent assay (ELISA) was used to test the serum samples for antibodies against C. burnetii. Univariable and multivariable analyses identified potential predictors of exposure in both livestock and humans.

Results: The overall seroprevalence of C. burnetii was 47.9% (95% CI: 45.7%-50.1%) in livestock and 44.7% (95% CI: 40.9%-48.5%) in humans. In livestock, significant variation in seroprevalence was found by species (p < 0.001). Goats were found to have significantly higher odds of being exposed to C. burnetii compared to cattle, sheep and camels. Both weaners and young animals had significantly lower odds of exposure compared to adults. In humans, the odds of C. burnetii exposure were lower among females compared to males. Herds seropositivity was also an important predictor of humans’ exposure to C. burnetii.

Conclusions: This study provides evidence of high seroprevalence of C. burnetii in both livestock and humans, highlighting the need for active surveillance programs targeting both populations. These programs should focus on identifying active shedding and implementing targeted control measures to mitigate the public health risks associated with C. burnetii.