Suspecting Coxiella burnetii Pneumonia (Q Fever)

Clinical Presentation

The Centers for Disease Control and Prevention recommends suspecting Coxiella burnetii pneumonia in patients with community-acquired pneumonia who present with fever, severe headache, and myalgia, particularly those with exposure to farm animals or residence in rural agricultural areas 1, 2
Fever typically lasts a median of 10 days in untreated patients and is a cardinal symptom, according to the CDC 2, 3
Severe, debilitating headaches may be retroorbital, associated with photophobia, or radiating to the jaw, as reported by the CDC 2, 3
Myalgia and fatigue are among the most frequently reported symptoms, with nonproductive cough present in approximately 50% of patients with Q fever pneumonia, as noted by the CDC 2, 3

The CDC suggests that exposure to farm animals, such as cattle, sheep, or goats, or residence in rural agricultural areas, increases the risk of Q fever pneumonia 4, 5
Living in a rural area or within 10 miles of a farm housing livestock also increases the risk, according to the CDC 2
Occupations with increased animal contact, such as veterinarians or farmers, are at higher risk, as reported by the CDC 2

The CDC recommends paired serum samples showing fourfold change in IgG antibody titer to C. burnetii phase II antigen by immunofluorescence assay (IFA) for diagnosis 6, 7
Single IgG titer ≥1:128 to C. burnetii phase II antigen by IFA in a patient ill for >1 week indicates probable acute infection, according to the CDC 6
PCR on whole blood or serum during acute phase (first 2 weeks of symptoms) is also recommended by the CDC 8, 9

The CDC advises that early doxycycline treatment (within first 3 days of symptoms) is most effective, and treatment should not be delayed while awaiting laboratory confirmation if Q fever is strongly suspected 9