Emergency Central is a collection of disease, drug, and test information including 5-Minute Emergency Medicine Consult, Davis’s Drug, McGraw-Hill Medical’s Diagnosaurus®, Pocket Guide to Diagnostic Tests, and MEDLINE Journals created for emergency medicine professionals. Explore these free sample topics:
-- The first section of this topic is shown below --
- Tularemia is an acute febrile illness caused by the small aerobic gram-negative pleomorphic intracellular coccobacillus Francisella tularensis:
- Organism is highly infectious.
- Person-to-person transmission has not been reported.
- Humans become infected through different environmental exposures:
- Bites from infected tick, deerfly, mosquito, or other infected insect
- Direct contact with infectious animal tissue or fluid
- Contact with or ingestion of contaminated food, water, or soil
- Inhalation of infected aerosols (e.g., cutting grass with power mowers, which may aerosolize the organism)
- The 4 major strains of the bacterium have different virulence and geographic location:
- 2 subspecies cause human infection in North America: F. tularensis subspecies tularensis (type A, more virulent) and F. tularensis subspecies holartica (type B, less virulent)
- Natural hosts:
- Lagomorphs and other rodents
- Found in species of wild animals (insects, rabbits, hares, ticks, flies, muskrats, beavers, mice), domestic animals (sheep, cattle, cats), ticks, and water and soil contaminated by infected animals
- Natural vectors:
- Biting flies
- Wild rabbits
- Weaponization of tularemia was accomplished during the Cold War:
- Because of its virulence and ability to be aerosolized, it remains a potential biologic agent for mass destruction.
- Lab technicians handling culture specimens are at high risk:
- F. tularensis cultures should be manipulated only in a biosafety level 3 facility.
- Also known as “rabbit fever” or “deerfly fever”
- Individuals who spend time outdoors in endemic areas are at higher risk:
- Forest workers
- Those who handle animal carcasses are at highest risk (taxidermists and butchers).
- Two-thirds of cases occur in males.
- Although tularemia can occur worldwide, it is endemic in the northern hemisphere:
- Reported nationwide except in Hawaii
- States with the highest incidence include Missouri, Arkansas, Kansas, South Dakota, and Oklahoma.
- Few hundred cases annually in US, although probably underreported
- Peak season is June–October.
- Mortality is 5–15%. Appropriately treated patients have mortality as low as 1%.
- 25% of cases occur in children 1–14 yr of age.
- Children who spend time outdoors in endemic rural areas are at highest risk.