Tularemia

Tularaemia is a zoonosis caused by Francisella tularensis, a highly infectious intracellular Gram negative coccobacillus.

• Subspecies tularensis (type A, most virulent, North America) and holarctica (type B, Europe and Asia).
• Transmission: tick and deer fly bites, handling infected animals (rabbits, hares, rodents), ingestion of contaminated water or food, and inhalation of aerosols (laboratory workers, landscaping).
• Clinical forms: ulceroglandular (most common, 60 to 70%), glandular, oculoglandular, oropharyngeal, pneumonic, and typhoidal.
• Case fatality is under 2% treated, 5 to 15% for type A untreated, and higher for pneumonic forms.
• Category A potential bioterror agent.

• Abrupt fever, chills, headache, myalgia, and fatigue 3 to 5 days after exposure (range 1 to 14).
• Ulceroglandular: painful skin ulcer at the inoculation site with tender regional lymphadenopathy (often suppurating).
• Pneumonic: cough, pleuritic pain, hilar adenopathy, and pleural effusions.
• Oropharyngeal: exudative pharyngitis and cervical adenopathy.
• Typhoidal: fever, hepatosplenomegaly, and sepsis without localising features.

• Serology (microagglutination, ELISA; fourfold rise or single titre of 1:160 or more), PCR on swabs, aspirates, and tissue, and culture on cysteine enriched media (notify the laboratory because of high infection risk).
• Chest imaging for pneumonia.
• Exclude cat scratch disease, anthrax, plague, sporotrichosis, tuberculous lymphadenitis, brucellosis, and staphylococcal or streptococcal infection.
• Notification to public health authorities.

• Severe disease: gentamicin 5 mg/kg/day IV in once daily dosing for 10 days (monitor levels), or streptomycin 1 g IM twice daily for 7 to 14 days.
• Mild to moderate disease: doxycycline 100 mg twice daily for 14 to 21 days, or ciprofloxacin 500 mg twice daily for 10 to 14 days (400 mg IV every 12 hours initially).
• Beta lactams, macrolides, and cephalosporins are ineffective.
• Drainage of fluctuant lymph nodes; ophthalmology review for oculoglandular disease.
• Post-exposure prophylaxis (doxycycline 100 mg twice daily or ciprofloxacin 500 mg twice daily for 14 days) after high risk exposure.
• Prevention: avoid handling wild animals without gloves, tick protection, and proper cooking of game meat.