Which bacterium causes tularemia, a zoonotic disease sometimes called rabbit fever?

Francisella tularensis causes tularemia, a zoonotic disease sometimes called rabbit fever.

Tularemia is associated with wild mammals, especially rabbits and hares, but the bacterium can spread through tick bites, contact with infected animals, contaminated water, inhalation, or ingestion. Different routes of exposure can produce different clinical forms.

F. tularensis is a very small Gram-negative bacterium that can survive and multiply inside host cells. It is highly infectious, meaning relatively few organisms can cause disease. The organism was first isolated during investigations of a plague-like illness in California in the early twentieth century.

Tularemia is not the same disease as plague, although both can involve fever and swollen lymph nodes. The bacterium’s environmental persistence and multiple transmission routes have also made it important in public-health preparedness discussions.