Q Fever

Most common zoonotic disease in Australia

• Difficult to distinguish clinically from other infectious diseases
• Exposure from livestock – cattle, sheep, goats, Also in other wildlife, bird and ticks
• Risks – farming, veterinary procedures, birthing, butchering
  • But also seen along transport routes, mowing in areas with droppings, exposure to native animals
  • Direct Exposure: Inhalation of infected aerosols from birth fluids, placenta, etc.
  • Indirect Exposure: Inhaling infected dust blown by wind or handling contaminated materials.
  • Person to person spread rare

• Coxiella Burnetii
  • Gram negative intracellular
  • Reservoir: Domestic and wild animals (kangaroos, bandicoots, rodents) and their ticks.
  • Transmission: Infected animals excrete organisms in urine, feces, milk, birth fluids, placenta, etc.
  • Survival: C. burnetii can survive harsh conditions for over a year, remaining infectious. can survive in dust or aerosols -secretions from infected animals – spread by inhalation
  • Contamination: Organism can contaminate hide, fleece, and surroundings.
• Present in all countries except NZ
• Incubation Period:
  • Range: 14 to 60 days, depending on exposure intensity.
  • Shortest: Those exposed to products of conception; longer for others.

Differentials

• Ross River/ Barmah Forrest, dengue, Epstein-Barr, Legionella, psittacosis, leptospirosis, brucellosis, rickettsial infections, influenza, CMV, mycoplasma pneumonia

Clinical

• Rapid onset of fever and chills that can last several weeks
• Profuse sweating
• Severe headache
• Aching muscles and joints
• Extreme fatigue and mental confusion
• Nausea and diarrhoea
• Photophobia or blurred vision
• Pneumonia
• Weight loss
• Hepatitis (with or without jaundice)
• Rash

Investigation

• FBC
  • Lymphopenia
  • Thrombocytopenia
• LFTs – AST and ALT deranged
• CRP
  • significantly elevated during the acute phase
  • may be normal in chronic Q fever
• PCR
  • Ideally within one week
  • Bacteria rapidly eliminated so negative does not exclude
• Serology
  • phase 2 IgM antibody =positive  
  • phase 1 and phase 2 IgG and IgM C. burnetii serology
  • Can take several weeks to become positive
  • Take multiple sample – recollect after 7 days to demonstrate rising titre
• Avoid culture – if needed state concern – special biohazard precautions

Treatment

• Doxycycline 100mg twice daily for 14 days

Prevention

• Can vaccinate adults but only if prior exposure definitely excluded – history, skin prick test and serology are required
• Livestock workers, Vets, wildlife carers/hunters, maintenance workers at high risk areas, living down wind of transport routes
• Need a month before exposure for protection
• N95 mask, hand hygiene

Chronic Q fever

• Chronic Endocarditis: Life-threatening; develops post-acute phase, rare (~1%).
• granulomatous hepatitis
• osteomyelitis
• Chronic Fatigue Syndrome (QFS):
  • affects 10–15% of patients after acute Q fever
  • Symptoms: Debilitating fatigue, muscle/joint pains, headaches, sweats, altered mental state. Alcohol intolerance is a commonly reported feature.
  • Duration: May last for 5-10+ years; significant cost to healthcare systems and industry.
  • Diagnosis: Currently relies on patient-reported symptoms; no definitive laboratory test.
  • Underlying Cause: Possible chronic dysregulation of cellular immune system due to persistent organism or antigens.
  • Prevention: Vaccination could mitigate chronic sequelae and associated costs.

Q Fever Vaccine Guide