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Coxiella burnetii (Q Fever) — Detailed Review

Zoonotic infection from livestock with acute febrile illness, pneumonia, hepatitis, and chronic endocarditis.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Internal Medicine department. Book Appointment →

What is Coxiella burnetii (Q Fever) — Detailed Review?

Q fever is a worldwide zoonotic infection caused by Coxiella burnetii, an obligate intracellular gram-negative bacterium with extreme environmental resistance. The primary reservoir is domestic and wild ruminants (sheep, goats, cattle), which shed the organism in birth products, urine, feces, and milk. Humans typically acquire infection by inhalation of contaminated aerosols, less commonly by ingestion or tick bite.

Acute Q fever follows incubation of 2-3 weeks. Most infections (50-60%) are asymptomatic. Symptomatic acute disease presents as a febrile illness, atypical pneumonia, granulomatous hepatitis, or 'doughnut granulomas' on liver biopsy. Pregnant women with acute Q fever may develop placentitis and obstetric complications.

Chronic Q fever (less than 5% of acute) presents months to years later, typically as endocarditis (especially with prosthetic or damaged valves), vascular infections (aneurysm, graft), osteomyelitis, or chronic hepatitis. Diagnosis is serologic with phase I and phase II IgG antibodies; phase I IgG over 1:1024 with phase II IgG over 1:256 indicates chronic infection. Acute disease is treated with doxycycline 100 mg BID for 14 days; chronic disease requires doxycycline plus hydroxychloroquine for at least 18-24 months.

Symptoms

Acute: high fever, severe headache (frontal)
Chills, sweats, myalgia
Atypical pneumonia (cough, dyspnea, chest pain)
Hepatitis (RUQ pain, jaundice rare, elevated transaminases)
Maculopapular rash (uncommon)
Pericarditis or myocarditis
Meningoencephalitis (rare)
Pregnancy: low birth weight, preterm labor, miscarriage
Chronic endocarditis: low-grade fever, fatigue, weight loss
Heart murmur, embolic events
Vascular infection: aneurysm rupture, graft infection
Bone or joint pain (osteomyelitis)
Hepatomegaly, splenomegaly
Anemia, thrombocytopenia (chronic)
Post-Q fever fatigue syndrome (chronic fatigue)

Risk Factors

Livestock farming (sheep, goats, cattle)
Veterinary work, abattoir or meat processing
Wool or hide industry
Dairy worker
Researcher with C. burnetii (aerosol risk)
Living near farms or during birthing season
Visit to petting zoo, farm tour
Pre-existing valve disease (chronic Q fever)
Vascular prosthesis (aortic graft)
Pregnancy
Immunosuppression
Older age (chronic Q fever)
Ingesting unpasteurized dairy (less common)
Tick bite (less efficient transmission)
Outbreaks (Netherlands 2007-2010 farm-associated)

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Fever, severe headache, atypical pneumonia in farmer
  • Pregnancy with fever and livestock exposure
  • Persistent fatigue and elevated LFTs in livestock worker
  • Heart murmur with prior Q fever
  • New aneurysm with constitutional symptoms
  • Persistent fever after recent farm exposure
  • Travel to outbreak region with febrile illness
  • Endocarditis with negative blood cultures
  • Veterinarian or abattoir worker with prolonged fever

Treatment Methods

01
Infectious diseases consultation
02
Phase I and phase II IgG, IgM antibody serology (gold standard)
03
PCR on blood, BAL, valve tissue (early disease)
04
Echocardiogram (TTE then TEE) for endocarditis suspicion
05
PET-CT for vascular and chronic infections
06
Liver biopsy for hepatitis (doughnut granuloma)
07
Acute Q fever: doxycycline 100 mg BID for 14 days
08
Pregnancy: trimethoprim-sulfamethoxazole until delivery (avoid doxycycline)
09
Pediatric: TMP-SMX or weight-based doxycycline (consider risks)
10
Chronic Q fever: doxycycline 100 mg BID plus hydroxychloroquine 200 mg TID for at least 18-24 months
11
Monitor doxycycline level (target 5 mg/L) and hydroxychloroquine level (target 0.8-1.2 mg/L)
12
Phase I IgG titer monitoring during chronic therapy (target reduction over time)
13
Surgical management of infected vascular grafts or valves when appropriate
14
Echocardiogram every 6-12 months in valve disease history after acute Q fever
15
Avoid live vaccines if immunosuppressed during therapy
16
Hydroxychloroquine: monitor retinopathy, ECG (QT prolongation)
17
Doxycycline: photoprotection, dental warnings in pregnancy/pediatric
18
Public health reporting (notifiable in many countries)
19
Outbreak investigation, vaccinate at-risk livestock workers (Australia: Q-VAX)
20
Chronic post-Q fever fatigue: graded exercise, supportive care
21
Pasteurized dairy products only
22
Multidisciplinary care: ID, cardiology, vascular surgery, ob-gyn

Which Department to Visit?

You can visit our Enfeksiyon Hastalıkları department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.