Francisella tularensis

• Zoonontic infection of a fastidious Gram-negative coccobacillus, carried on rodents & rabbits and transmitted by biting insects
• Presentation depends on route of entry: (ulcero)glandular, oculoglandular, pharyngeal, typhoidal, or pneumonic
• Treatment is streptomycin for __ weeks

Definition

• Zoonotic infection with Francisella tularensis, a fastidious Gram-negative coccobacillus
• Also called rabbit fever

History

• Discovered in 1911 in Tulare county, California
• Deer fly fever, rabbit fever, etc...

Syndromes

1. Ulceroglandular: ulcer develops at site of innoculation with tender lymphadenopathy and systemic symptoms
2. Glandular: ulcer is undetectable or healed, only lymphadenopathy and systemic illness remains
3. Oculoglandular: entry through the conjuctiva
4. Pharyngeal: entry through the oropharynx, with exudative pharyngitis/tonsillitis
5. Typhoidal: febrile illness without lymphadenopathy or ulcer, sometimes with diarrhea; patient often has an underlying chronic disease
6. Pneumonic: direct inhalation, often from sheep shearing, landscaping, and microbiology laboratory work

Epidemiology

• Essentially worldwide Northern Hemisphere distribution, especially in the US, Japan, Russia, and Scandinavian countries
• Main animal reservoirs are rodents and rabbits
• Transmission
  • Bite of ticks, biting flies, or mosquitoes (Europe)
  • Exposure to animal products, including skinning, dressing, and eating wild game
  • Also from animal stool or bites, including cats that have killed infected rodents

Diagnosis

• Culture: Grows slowly on standard culture media, needs cystine-rich media (e.g. chocolate agar, BHI, or cystine media)
  • Looks bacillary in logarithmic growth phase (small Gram-negative rod), slow-growing only on chocolate agar
• Serology (EIA) can be used in the right context
• PCR

Presentation

• Based primarily on route of entry (see Syndromes, above)

Management

• Streptomycin IM if severe (amikacin/other AG IV here) x2wks
• Doxy or cipro if mild, x2wks