Q Fever

Key Features

• Caused by inhalation of Coxiella burnetii

• Exposure to farm animals (sheep, goats, cattle) and pets

• Unpasteurized milk from infected animals may also transmit disease

• Flu-like illness (fever, severe headache, myalgia)

• Cough; atypical pneumonia

• Hepatomegaly and hepatitis

Clinical Findings

• Abrupt onset of self-limited flu-like syndrome occurring 10–25 days after exposure

• Abdominal pain, vomiting, chest pain, and dry cough are prominent in children

• Hepatosplenomegaly is common

• Illness lasts 1–4 weeks and frequently is associated with weight loss

Diagnosis

• Leukopenia with left shift is characteristic

• Aminotransferase and γ-glutamyl transferase levels are elevated

• Diagnosis is made by finding an antibody response (fourfold rise or single high titer in ELISA; IFA, or CF antibody assay) to the phase II organism

• Chronic infection is indicated by antibody against the phase I organism

• Pneumonitis occurs in 50% of patients

• Multiple segmental infiltrates are common, but the radiographic appearance is not pathognomonic

Treatment

• Self-limited, illness typically lasts 1–2 weeks without therapy

• Doxycycline shortens course of uncomplicated illness

• Therapy is continued for several days after the patient becomes afebrile (usually 10–14 days)

• Quinolones are also effective