Coxiella

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Pathogen and Disease

Coxiella burnetii, the etiological agent of "Q fever," is a category B bioterrorism agent that is highly infective to both humans and livestock. In humans, the disease manifests as an acute flu-like illness, with a hallmark debilitating headache and cyclic fever.

Bacterial Classification

Although Coxiella was historically considered "Rickettsia-like," 16S rRNA gene sequence analysis and genome analysis (based on shared proteins across genomes and phylogenetic analysis of a set of 20 highly conserved proteins) indicate that it is a gamma-proteobacteria (order Legionellales) and thus is distant from the alpha-proteobacterial Rickettsia group. Coxiella is also distant from any other lineage within the gamma subgroup, its closest relationship is with Legionella pneumophila, a facultative intracellular human pathogen, and Rickettsiella grylli, an intracellular arthropod pathogen (Seshadri et al., 2003).

For references and expanded information, please refer to the C. burnetii PathInfo document.