Coxiella burnetii

Coxiella burnetii

Hosts

Animal and human

Transmission/Exposure Routes

Infection of humans usually occurs by inhalation of these organisms from air that contains airborne barnyard dust contaminated by dried placental material, birth fluids, and excreta of infected animals

Case Fatality Ratio

The estimated case fatality rate is low, at < 2% of hospitalized patients. Treatment with the correct antibiotic may shorten the course of illness for acute Q fever (wikipedia)

Incubation periods

The acute symptoms usually develop within 2-3 weeks of exposure, although as many as half of humans infected do not show symptoms (CDC)

Burden of Disease

Q Fever became a reportable disease in the United States in 1999. Between 2000 and 2004, the US saw an average of 51 cases every year. In 2005, 136 cases were reported to the CDC, and 169 in 2006. Here have been reported cases in US military personnel deployed in Iraq and Afghanistan, as well as civilian contractors who work in those countries (Struble, K. 2012).
Internationally, prevelance is estimated from 5% in urban areas to 30% in rural areas. This is likely and underestimate due to asymptomatic infections. Results of serological testing of blood donors revealed a prevalence of 18% to 37% in Africa. The United Kingdom sees approximately 100 cases of Q Fever a year (Struble, K. 2012).

Microbiology

Obligate intracellular small Gram-negative bacteria

Environmental Survival

The organism is extremely hardy and resistant to heat, drying, and many common disinfectants which enable the bacteria to survive for long periods in the environment

Recommended Dose Response Model

Dose response models for Coxiella burnetii
Beta-Poisson: α is 0.36, N₅₀ is 4.93E+08

References

Struble, K. Cunha, B. (2012) "Q Fever" Medscape Reference. Retrieved on 2-1-2012 from http://emedicine.medscape.com/article/227156-overview#a0156
http://www.cdc.gov/qfever/
http://en.wikipedia.org/wiki/Coxiella_burnetii