Q Fever

Greatest after direct or indirect exposure to infected cattle, sheep, or goats; particularly at parturition

Less from a variety of other animals, rarely from blood products

Abattoir workers, veterinarians, and other animal workers at greatest risk

Pts with immune impairment are at a higher risk (e.g., HIV, steroids)

Mortality 2.4% overall; chronic infection ∼16%.

Decreased respiratory reserve secondary to pneumonia

Decreased myocardial reserve secondary to endocarditis

Further increase in hepatocellular injury if there is liver involvement

Secondary respiratory complications

Decreased myocardial performance and emboli with endocarditis

Hepatic or neurologic involvement

Acute infection: Asymptomatic (∼50%) to moderate severity (2% hospitalized).

Acute symptomatic disease presents as nonspecific febrile syndrome ± pneumonitis (∼50%), hepatitis (80% or more), pericarditis and/or myocarditis (<5%), neurologic disease (<5%).

Chronic disease occurs in <1% of infections, usually without fever.

Chronic disease, primarily endocarditis (particularly abn or prosthetic valves) and occasionally bone.

Coxiella burnetii , the causative organism, is a fastidious obligate intracellular bacterium.

The spore stage can withstand harsh environmental conditions for prolonged periods, facilitating indirect transmission.

Highly infectious; transmitted (1–10 organisms) primarily by inhalation, from unpasteurized milk, or by a tick bite.

Incubation period ∼20 d (range, 3–40 d).

Bacterium targets reticuloendothelial cells and develops into granuloma.