Presence of Coxiella burnetii DNA in the environment of the United States, 2006 to 2008 - PubMed (original) (raw)

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

Gilbert J Kersh et al. Appl Environ Microbiol. 2010 Jul.

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.

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Figures

FIG. 1.

FIG. 1.

Percentage of Coxiella_-positive samples at each of the 18 sampling sites. Environmental samples were evaluated for the presence of C. burnetii DNA using an IS_1111 PCR assay. Approximately 90 samples were acquired at each of the 18 sites, and the percentages with C. burnetii DNA are shown. RM, Rocky Mountains; SC, south-central; UM, Upper Midwest; WC, West Coast; EC, East Coast; DS, Deep South.

FIG. 2.

FIG. 2.

Comparison of the percentages of _Coxiella_-positive samples to environmental factors. The percentages of samples with C. burnetii DNA at each of the 18 sampling sites were plotted against livestock density (A), human population density (B), annual mean temperature (C), and annual mean precipitation (D). Livestock density was based on the number of cows and sheep per square mile in the county of the sampling site. Cow and sheep numbers were determined from the 2002 USDA Census of Agriculture. Human population density was determined from 2000 U.S. Census data. Temperature and precipitation data were taken from the National Climatic Data Center annual climatological summary for 2007. The correlation coefficients (r) for each data set are indicated in the top right of each plot.

FIG. 3.

FIG. 3.

Percentage of Coxiella_-positive samples that were taken from locations that had livestock or taken from locations without livestock. This analysis was done on all samples (A) and on highly positive samples (B). Samples were defined as highly positive if they had a CT value in the IS_1111 PCR assay of less than 34. For statistical analysis, the data were entered into a two-by-two table, and the Pearson's chi-square values were 22.06 with a P of <0.00001 for panel A and 52.62 with a P of <0.00001 for panel B. The values above the bars indicate the number of positive samples/number of samples tested.

References

    1. Anderson, A. D., D. Kruszon-Moran, A. D. Loftis, G. McQuillan, W. L. Nicholson, R. A. Priestley, A. J. Candee, N. E. Patterson, and R. F. Massung. 2009. Seroprevalence of Q fever in the United States, 2003-2004. Am. J. Trop. Med. Hyg. 81:691-694. - PubMed
    1. Bamberg, W. M., W. J. Pape, J. L. Beebe, C. Nevin-Woods, W. Ray, H. Maguire, J. Nucci, R. F. Massung, and K. Gershman. 2007. Outbreak of Q fever associated with a horse-boarding ranch, Colorado, 2005. Vector Borne Zoonotic Dis. 7:394-402. - PubMed
    1. Beare, P. A., N. Unsworth, M. Andoh, D. E. Voth, A. Omsland, S. D. Gilk, K. P. Williams, B. W. Sobral, J. J. Kupko III, S. F. Porcella, J. E. Samuel, and R. A. Heinzen. 2009. Comparative genomics reveal extensive transposon-mediated genomic plasticity and diversity among potential effector proteins within the genus Coxiella. Infect. Immun. 77:642-656. - PMC - PubMed
    1. Coleman, S. A., E. R. Fischer, D. Howe, D. J. Mead, and R. A. Heinzen. 2004. Temporal analysis of Coxiella burnetii morphological differentiation. J. Bacteriol. 186:7344-7352. - PMC - PubMed
    1. Dupuis, G., J. Petite, O. Peter, and M. Vouilloz. 1987. An important outbreak of human Q fever in a Swiss Alpine valley. Int. J. Epidemiol. 16:282-287. - PubMed

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