Epidemiology
Etiology
Pathogen
- Coxiella burnetii (gram-negative, intracellular)
- Morphological similarities to Rickettsia
- Can survive in harsh environments in a spore-like form
Route of transmission
- Direct infection (no vector transmission)
- Vector transmission: primary reservoir are cattle, sheep, and goats
- Inhalation of spore-containing aerosols from the amniotic fluid or secretions of infected livestock
- Ingestion of raw milk produced by infected animals
Risk groups
- Slaughterhouse workers, farmers, shepherds, veterinarians
Pathophysiology
Clinical features
- Incubation period: ~2-3 weeks.
- Acute Q Fever:
- Often asymptomatic or a mild, self-limiting febrile illness.
- Atypical pneumonia: Can range from mild cough to severe respiratory distress.
- Severe retro-orbital headache is a hallmark symptom.
- Other Sx: High fever (>40°C or 104°F), myalgias, fatigue, hepatitis (granulomatous).
- Classic triad: High fever, severe headache, and hepatitis.
- Notably, rash is rare, differentiating it from many other rickettsial diseases.
- Chronic Q Fever:
- Develops months to years after acute infection.
- Most common manifestation is culture-negative endocarditis.
- High risk in pts with pre-existing valvular heart disease, immunosuppression, or pregnancy.
Diagnostics
Treatment