Tularemia: Background

Tularemia is an infection caused by the bacterium Francisella tularensis. It can affect people, rabbits, hares, rodents, dogs, cats, pigs, sheep and horses. Other animals may also act as unaffected reservoirs. Outbreaks in wildlife, spread occurs through direct animal-to-animal contact, ticks and biting flies.

People may be exposed to tularemia by biting flies, ticks and improper handling of animal carcasses. Some exposures have also occurred in gardeners while mowing or cutting weeds around sites where wildlife mortalities have occurred. Onset of signs and symptoms typically occur within three to five days, but can take as long as 14 days to develop.

In wildlife in Arizona, tularemia has been most commonly associated with mortalities in cottontails. Often the only sign is sudden death. Examination of the carcass may reveal small white spots on the liver and spleen.