Q fever

Background

• Described in 1937: occupational disease of abattoir workers (manage animals before and after slaughtering process) and dairy farmers
• Caused by Coxiella burnetii
  • Obligate intracellular bacteria morphologically similar to Rickettsia
  • Reservoirs include cattle, goat, sheep, and ticks (Dermacentor andersoni)
• CDC: category B biologic warfare agent due to its inhaled infectivity
• Worldwide disease

Clinical Features

• Symptoms usually develop within 2-3 weeks, although up to half of those infected may not show symptoms
  • high fevers (up to 104-105°F)
  • severe headache
  • general malaise
  • myalgias
  • chills/sweats
  • non-productive cough
  • nausea/vomiting
  • diarrhea
  • abdominal pain
  • chest pain
• Complications include pneumonia, granulomatous hepatitis (inflammation of the liver), myocarditis (inflammation of the heart tissue), and central nervous system complications.
• Endocarditis is the major form of chronic disease
• Infection in pregnancy is more likely to be asymptomatic, but often results in chronic Q fever and obstetrical complications

Differential Diagnosis

Fever in traveler

• Normal causes of acute fever!
• Malaria
• Dengue
• Leptospirosis
• Typhoid fever
• Typhus
• Viral hemorrhagic fevers
  • Ebola virus disease
  • Marburg virus disease
  • Lassa fever
  • Crimean-Congo hemorrhagic fever
• Chikungunya
• Yellow fever
• Rift valley fever
• Q fever
• Amebiasis
• Zika virus

Lower Respiratory Zoonotic Infections

• Psittacosis
• Anthrax (Bacillus anthracis)
• Brucellosis (Brucella species)
• Q fever (C. burnetti)
• Pasteurellosis (Pasteurella multocida)
• Melioidosis (Burkholderia pseudomallei)
• Rocky Mountain Spotted Fever (R. rickettsii)
• Pulmonic Plague (Yersinia pestis)
• Influenza A
• Hantavirus

Diagnosis

• CBC, Complete Metabolic Panel – Liver enzymes usually elevated 2-10 times normal
• Blood cultures
• CXR

Management

• Doxycycline
  • Adults: 100 mg BID
  • Children < 45 kg: 2.2 mg/kg BID
• Patients should be treated for at least 3 days after the fever subsides and until there is evidence of clinical improvement. Standard duration of treatment is 2-3 weeks.

Disposition

Most patients require admission for further workup

References

• http://www.cdc.gov/qfever/
• http://www.ncbi.nlm.nih.gov/pubmed/16168313