Presence and Persistence of Coxiella burnetii in the Environments of Goat Farms Associated with a Q Fever Outbreak

Abstract

ABSTRACTQ fever is a zoonotic disease caused by inhalation of the bacteriumCoxiella burnetii. Ruminant livestock are common reservoirs forC. burnetii, and bacteria present in aerosols derived from the waste of infected animals can infect humans. The significance of infection from material deposited in the environment versus transmission directly from infected animals is not known. In 2011, an outbreak of Q fever cases on farms in Washington and Montana was associated with infected goats. A study was undertaken to investigate the quantity and spatial distribution ofC. burnetiiin the environment of these goat farms. Soil, vacuum, and sponge samples collected on seven farms epidemiologically linked to the outbreak were tested for the presence ofC. burnetiiDNA by quantitative PCR. Overall, 70.1% of the samples were positive forC. burnetii. All farms had positive samples, but the quantity ofC. burnetiivaried widely between samples and between farms. High quantities ofC. burnetiiDNA were in goat housing/birthing areas, and only small quantities were found in samples collected more than 50 m from these areas. Follow-up sampling at one of the farms 1 year after the outbreak found small quantities ofC. burnetiiDNA in air samples and large quantities ofC. burnetiipersisting in soil and vacuum samples. The results suggest that the highest concentrations of environmentalC. burnetiiare found in goat birthing areas and that contamination of other areas is mostly associated with human movement.