A serosurvey of Coxiella burnetii infection in children and young adults in South West Queensland

Objective: To describe the seroepidemiology of Coxiella burnetii, the causative agent of Q fever, in those under 25 years of age in South West Queensland. Methods: A convenience sample of residual sera from a diagnostic laboratory was tested for C. burnetii antibodies by immunofluorescence at 1:10 dilution. Prevalence and annual incidence were calculated from the results. Results: Twenty-nine of 447 (6.5%, 95% CI 4.5%-9.2%) samples were positive. Seropositivity increased from 2.5% in those <15 (95% CI 1.0%-5.5%) to 11.0% in those 15-24 years old (95% CI 7.4%-16.0%). The estimated annual incidence for the latter age group was 7.7 per 1,000. Conclusions: Q fever is a relatively common infection in South West Queensland, even in those aged < 15 years for whom the vaccine is not recommended. Implications: Vaccination programs, such as the federally funded National Q fever Management Program, are needed in this and similar high risk rural areas.