Coxiella burnetii Infection

Abstract

Coxiella burnetii is an obligate intracellular bacterium that causes a worldwide zoonosis, Q fever, and can be misused as a biological warfare agent. Infection in animals (coxiellosis) is mostly persistent. Infection in humans is often asymptomatic, but it can manifest as an acute disease (usually a self-limited flu-like illness, pneumonia, or hepatitis) or as a chronic form (mainly endocarditis, but also hepatitis and chronic fatigue syndrome). C. burnetii infection in pregnant women may result in abortions, premature deliveries, and stillbirths. Infection in nature is maintained and transmitted by ticks as the principal vector and reservoir. Cattle, sheep, and goats are the most important source of human infections. Humans contract C. burnetii infection mostly by aerosol in contact with contaminated environs, wind playing an important factor in spreading the infection. The wide distribution of C. burnetii contributes to a high resistance of its extracellular small cell variant to environmental conditions. Its intracellular large cell variant, adapted to survive under harsh conditions of phagolysosomes, enables long-term survival and persistence of C. burnetii, namely in monocytes/macrophages. Host factors such as underlying disease and cell-mediated immunity play a decisive role in the clinical expression of C. burnetii infection. Complete genome analysis of C. burnetii will certainly contribute to better understanding of the pathogenesis of C. burnetii infection and will improve Q fever diagnosis and immunoprophylaxis.

Shedding routes ofCoxiella burnetiiin dairy cows: implications for detection and control

“…Animals and humans become infected mainly through inhalation of contaminated aerosols produced from shedder animals and the contaminated environment [3,20]. The similar proportion of positive faeces and vaginal mucus samples (Tab.…”

“…However, to our knowledge, the efficiency of this vaccine to prevent Coxiella burnetii shedding and to reduce the shed bacterial burden in infected cows has never been assessed in naturally-infected dairy cows. Control measures in contaminated environments mainly deal with precautions around parturition (calving box with cleaning and disinfection after each calving, destruction of the placenta and foetus) [3,12,20], decontamination of bedding material with, for instance, calcium cyanamide 0.4% as described for goat manure [2]. In addition, spreading manure on the pasture when the wind blows should be avoided [11].…”

“…Q fever is a widespread zoonosis that is caused by an obligate intracellular bacteria, Coxiella burnetii [3,5,6,20]. This disease, described for the first time among abattoir workers in Australia [14], is now recognised as being worldwide endemic [25,27] except in New-Zealand [19].…”

“…In that context, only techniques allowing the direct identification of Coxiella shedders appear to be informative for assessing the actual risk of transmission of the infection. Bacterioscopic examination (with a Stamp-Machiavello coloration) of stained smears, which is used routinely for the detection of Coxiella burnetii in the placenta of aborted cows, has poor specificity and sensitivity [3,20]. Moreover, bacteriological isolation requires confined level-3 laboratories and cannot be performed for mass-screening.…”

Coxiella burnetiishedding by dairy cows

“…Q fever is a zoonosis which is caused by an obligatorily intracellular bacterium, Coxiella burnetii [4,17]. This disease, described for the first time among abattoir workers in Australia [12], is now recognised as being endemic worldwide [23,25] except in New-Zealand [16].…”