II. Pathophysiology
- Coxiella Burnetii
- Gram Negative, small coccobacilli
- Obligate Intracellular Bacteria
- Similar to Rickettsiae, but has been reclassified to the family Coxiellaceae
- C. Burnetii uses host ATP within host cell to grow and divide
- Spore forming (Endospore)
- C. Burnetii can form an endospore (similar to Clostridium species)
- Endospore form is resistant to heat and dry air
- Endospore form allows organism to survive outside host cells for extended periods
- Organism lies dormant in endospore form (must be intracellular to grow and divide)
- Transmission
- Exposure to farm animals (esp. cattle, goats, sheep)
- Typically transmitted via aerosolized C. Burnetii spores
- Animal feces
- Dried cow placenta
- Dried tick feces on hides
- Contaminated soil
- May also be transmitted by the ingestion of unpasteurized milk
- To be destroyed, Coxiella Burnetii endospores must be heated to at least 60 C
- Tick Borne Illness transmission occurs, but is rare
- Incubation
- Three weeks (ranges from 9-40 days)
III. Symptoms
- Flu-like symptoms
- Fever
- Malaise
- Headache
- Myalgias
- Arthralgias
- Respiratory symptoms (mild, Atypical Pneumonia similar to Mycoplasma pneumonia)
- Dry cough
- Pleuritic Chest Pain
- Gastrointestinal symptoms
IV. Labs
- Blood Cultures are typically negative
- Coxiella Burnetii PCR
- Serology (IFA)
V. Management: Acute Infections
- Precautions
- See other references for chronic infections, endocarditis or comorbid endocarditis risk
- Non-Pregnant Adults and Children age >8 years
- Doxycycline 2.2 mg/kg up to 100 mg orally twice daily for 2 weeks
- Pregnancy
- Trimethoprim-Sulfamethoxazole DS 1 orally twice daily
- Continued until later third trimester to prevent Preterm Labor
- Discontinued prior to delivery to prevent Kernicterus
- Trimethoprim-Sulfamethoxazole DS 1 orally twice daily
- Children age <8 years
- Trimethoprim-Sulfamethoxazole for 14 days (see link for dosing)
VI. Complications
- Atypical Pneumonia
- Acute Respiratory Distress Syndrome (ARDS)
- Granulomatous Hepatitis
- Vascular Infections
-
Bacterial Endocarditis (2% of cases)
- Often culture negative
- Melenotte (2019) Clin Infect Dis 69(11):1987-1995 +PMID: 30785186 [PubMed]
- Chronic Infection (<5% of cases)
VII. Prognosis
- Most cases are mild and resolve spontaneously within 2 weeks
- However, Bacterial Endocarditis and chronic infections may complicate infection
VIII. Resources
- Q Fever (Wikipedia)
IX. References
- (2025) Sanford Guide, accessed on IOS 2/14/2025
- Black, Martin, DeVos (2018) Crit Dec Emerg Med 32(8): 3-12
- Nordurft-Froman and DeVos (2022) Crit Dec Emerg Med 36(4): 4-15
