Q Fever Related Community Infections, US Exposure to Coxiella burnetii

Coxiella burnetii is a significant infectious pathogen that causes Q fever. Q fever is thought to be uncommon in the US and most human cases are believed to occur in agricultural livestock workers. However, the extent of community exposure to C. burnetii isn't known with certainty. Using nationally representative US National Health and Nutrition Examination Survey serologic, demographic and occupational history data, the magnitude of US adult general population exposure to C. burnetii excluding agricultural sector workers was estimated. Exposure was defined as positive serum IgG antibodies by immunofluorescence assay (e.g. current or past infection). 3.0% (95% CI 2.0-4.4) of the US population met criteria for C. burnetii exposure, some 6.2 million persons. Overall, 86.9% (95%CI: 75.5-98.4) of seropositives had no lifetime history of work in the agricultural sector (5.5 million persons). This was consistently true across all US demographic groups: age 20-59 years 87.3%, age 60+ years 85.7%, men 86.1%, women 87.6%, Non-Hispanic Whites 82%, Non-Hispanic Blacks 95.8%, Mexican Americans 89.4%, immigrants from Mexico 83.5% and other immigrants 96.8%. As half of C. burnetii infections result in acute Q fever and chronic Q fever conveys significant mortality, community level risks to the general public may be significant.