Tularemia

Epidemiology

• Highly infectious after aerosolization
• Infectious dose can be as low as 10-15 organisms
• Person-to-person transmission does not occur

Clinical

• Incubation period is 3-6 days (ranges 1-21 days)
• Aerosolization would most likely result in typhoidal tularemia, with pneumonic involvement
• Typhoidal tularemia is a nonspecific illness, with fever, headache, malaise and non-productive cough (mortality rates can be as high as 30-60%)
• Diagnosis requires high index of suspicion given nonspecific presentation

Laboratory Diagnosis

• Bacterial cultures should be handled in a Biosafety Level 3 facility; isolation of organism can otherwise put laboratory workers at risk
• Organism is difficult to culture and grows poorly on standard media; cysteine-enriched media is required
• Serology is most commonly used for diagnosis

Patient Isolation

Standard precautions. Respiratory isolation not required.

Treatment

• Streptomycin (7.5 mg/kg IM q 12 hours × 10-14 days) or gentamicin (3-5 mg/kg/day IV or IM qd in 3 divided doses × 10-14 days) are the preferred antibiotics
• Tetracyclines are alternative choices, although they are bacteriostatic and associated with higher relapse rates and must be continued for at least 14 days

Prophylaxis

• Antibiotic prophylaxis is most effective if begun within 24 hours after exposure to aerosol
• Tetracyclines are recommended for 14 days