Presence of Coxiella burnetii DNA in the Environment of the United States, 2006 to 2008

Abstract

Coxiella burnetii is an obligate intracellular bacterium that causes the zoonotic disease Q fever. Because C. burnetii is highly infectious, can survive under a variety of environmental conditions, and has been weaponized in the past, it is classified as a select agent and is considered a potential bioweapon. The agent is known to be present in domestic livestock and in wild animal populations, but the background levels of C. burnetii in the environment have not been reported. To better understand the amount of C. burnetii present in the environment of the United States, more than 1,600 environmental samples were collected from six geographically diverse parts of the United States in the years 2006 to 2008. DNA was purified from these samples, and the presence of C. burnetii DNA was evaluated by quantitative PCR of the IS1111 repetitive element. Overall, 23.8% of the samples were positive for C. burnetii DNA. The prevalence in the different states ranged from 6 to 44%. C. burnetii DNA was detected in locations with livestock and also in locations with primarily human activity (post offices, stores, schools, etc.). This study demonstrates that C. burnetii is fairly common in the environment in the United States, and any analysis of C. burnetii after a suspected intentional release should be interpreted in light of these background levels. It also suggests that human exposure to C. burnetii may be more common than what is suggested by the number of reported cases of Q fever.

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

“…Al- though the effectiveness of the decontamination efforts was not evaluated, the high levels of organism in the goat pens and birthing areas and the persistence of high levels of C. burnetii in the home on farm 5 suggest that there was repeated introduction of C. burnetii into the home, most likely by people tracking C. burnetii back into the house after farm work. In a large environmental study published in 2010, many C. burnetii-positive samples were found at locations that were not near animals (10). A likely explanation for the introduction of C. burnetii into these locations is foot traffic from people that had recently visited areas directly contaminated by infected livestock.…”

“…In a 1989 outbreak in the United Kingdom, Q fever cases were reported up to 11 miles (ϳ18 km) away from the farm that was the source of the outbreak (9). A study that examined a large number of environmental samples across the United States detected C. burnetii DNA by PCR in 23.4% of samples tested (10). Although the bacterial DNA was more likely to be detected in locations where livestock were housed or treated, a low level of DNA was found in many samples that were distant from animal housing locations.…”

The Sensitivity of the PCR Method for Detection of Coxiella burnetii in the Milk Samples

“…This bacterium is very stable in different environments. It is also highly infectious and one to ten organisms can cause Q fever in humans [5]. Also, C. burnetii can be present in milk, urine, feces, vaginal mucus and semen.…”

Circulation of Coxiella burnetii in a Naturally Infected Flock of Dairy Sheep: Shedding Dynamics, Environmental Contamination, and Genotype Diversity

“…Consequently, knowledge of C. burnetii's sources and shedding dynamics is essential to assessing the risks of disease transmission and pathogen persistence. On livestock farms, C. burnetii DNA has been found in various environmental matrices, such as dust (11)(12)(13) and aerosols (14)(15)(16). However, studies that examine the relationship between environmental contamination levels and the clinical status and shedding dynamics of ruminant herds are lacking.…”