Tularemia, acute, infectious febrile disease of a variety of animals, including rodents, foxes, coyotes, and skunks. It is transmitted to humans either by direct contact, as in skinning an infected rabbit, or by an insect vector, such as certain flies. Human-to-human transmission does not occur. Tularemia is caused by a bacterium, Francisella tularensis, an organism related to one that causes plague. In most cases the first symptoms are fever and chills, followed by a lump that soon ulcerates at the site of infection, often the hand, followed by enlarged glands at the elbow and in the armpit. While the ulcer is usually small and painless, the glands get quite large and painful, and they often burst and drain.

Fever in untreated cases may last for three to four weeks and run as high as 40° or 40.6° C (104° or 105° F). Other symptoms include general debility; often pneumonia develops, and in rare cases, involvement of the heart, abdominal cavity, bone, or meninges may occur. Treatment with antibiotics usually leads to prompt recovery from the disease.