Coxiella burnetii (Q fever) prevalence in associated populations of humans and small ruminants in The Gambia

Objectives: To simultaneously estimate the prevalence of antibodies against Coxiella burnetii (Q fever) among adults and small ruminants, and C. burnetii shedding prevalence among small ruminants in households in the Kiang West district of The Gambia, and to assess associated risk factors. Methods: Sera of 599 adults and 615 small ruminants from 125 compounds within 12 villages were tested for antibodies against C. burnetii using ELISA. Vaginal swabs and milk samples of 155 small ruminants were tested using PCR to investigate shedding of C. burnetii. Results: A total of 3.8–9.7% of adults, depending on ELISA test cut-off, and 24.9% of small ruminants in Kiang West were seropositive. Having at least one seropositive animal in one's compound was a risk factor for human seropositivity (OR: 3.35, 95% CI: 1.09–14.44). A grazing area within a village was a risk factor for seropositivity in small ruminants (OR: 2.07, 95% CI: 1.26–3.50); others were having lambed (OR: 2.75, 95% CI: 1.37–5.76) and older age of the animals (OR: 2.75, 95% CI: 1.37–5.76 for 1–3 years and OR 5.84, 95% CI: 3.10–11.64 for >3 years); 57.4% of sampled small ruminants were shedding C. burnetii. Conclusion: Coxiella burnetii infection is endemic among both humans and small ruminants in this area of The Gambia. Human and animal exposure to C. burnetii were related at compound level. Further research into the clinical relevance of C. burnetii infection in West Africa is needed.