Pneumonia is one manifestation of acute Q fever following infection with Coxiella burnetii. Fever, headache, and myalgia dominate the clinical picture of Q fever pneumonia. Cough is nonproductive and may be absent despite the presence of pneumonia. While in most instances pneumonia results in an illness of mild-to-moderate severity, on occasion it is rapidly progressive and results in respiratory failure. Infection occurs as a result of inhalation of contaminated aerosols. Infected cattle, sheep, and goats are the usual reservoirs for this zoonosis. In some areas, infected parturient cats serve as the reservoir, and in such instances, rounded opacities are seen on the chest radiograph. The diagnosis of C. burnetii pneumonia is usually confirmed by demonstration of a fourfold or greater rise in antibody titer. Treatment is usually with a tetracycline or rifampin for 7 to 10 days.