Coxiella burnetii

Coxiella burnetii is a species of intracellular, pathogenic bacteria, and is the causative agent of Q fever. The genus Coxiella is morphologically similar to the rickettsia, but with a variety of genetic and physiological differences. C. burnetii are small Gram negative bacteria with two growth phases, as well as a spore form which lies idle in soil. It can survive standard disinfectants, and is resistant to many other environmental changes.

Pathogenesis
The ID50 (the dose needed to infect 50% of experimental subjects) is one via inhalation&mdash; i.e. inhalation of one organism will yield disease in 50% of the population. Disease occurs in two states: An acute state presents with headaches, chills, and respiratory symptoms, and an insidious chronic stage.

While most infections clear up spontaneously, treatment with tetracycline or doxycycline appears to reduce the symptomatic duration and reduce the likelihood of chronic infection. A combination of erythromycin and rifampin is highly effective in curing and prevention of disease and so is vaccination with Q-vax vaccine (CSL).