Q fever pneumonia

Q fever pneumonia refers to pulmonary infection with the organism Coxiella burnetii. It is sometimes classified as an atypical pneumonia. It can occur as either sporadic or outbreak cases.

Clinical presentation

The clinical picture is often dominated by fever, headaches and myalgias . A cough, if present, is often nonproductive and may even be absent despite the presence of the pneumonia.

Pathology

Coxiella burnetii is an obligate intracellular parasite (zoonosis: small gram-negative coccobacillus) that lives in the phagolysosomes of the host cells. Common animal reservoirs include goats, cattle, sheep, cats, and occasionally dogs. The organism has a worldwide prevalence.

Serology

The diagnosis can be established serologically (i.e. total antibody or IgM).

Radiographic features

Plain radiograph

The radiographic differentiation of Q fever pneumonia from other types of community-acquired pneumonias is not possible. Segmental or lobar opacification and occasional pleural effusions may be seen (all of which are non specific features on their own). Features can be slow to clear .

CT chest

CT features are again individually non specific and often confirms airspace involvement, which can be lobar, segmental, patchy or a combination. Often more than one lobe may be involved.

Treatment and prognosis

Tetracycline is traditionally considered the drug of choice . Chloramphenicol, cotrimoxazole, and rifampin may also be effective. In most cases the pneumonia results in an illness of mild-to-moderate severity although on occasion can be rapidly progressive and may result in respiratory failure .

History and etymology

It was first described by E H Derrick in 1937 .