Tularemia is a rare infection caused by the bacteria Francisella tularensis. F. tularensis is a bacteria widely distributed in nature. This bacteria resides in many animal species and is transmitted by direct contact or a bite from a tick or deer fly. Amblyomma americanum and Dermacentor variabilis ticks may harbor and transmit this bacteria. Humans can also contract the illness through direct contact with an infected animal carcass, especially rabbits. Epidemics may also occur through ingestion of water contaminated with the bacteria. Rare cases have been reported in Michigan.

Clinical Manifestations:

Six classic forms of the disease have been described: ulceroglandular, glandular, oculoglandular, typhoidal, intestinal, and pneumonic. The most common manifestation of F. tularensis in the U.S. is the ulceroglandular form as a result of tick bites or contact with an infected animal. The average incubation period is approximately 3 to 5 days, but can vary from 1 to 21 days.

Symptoms:

• Ulcerative lesion at the site of inoculation

• Regional lymph node swelling

• Pneumonia

• Fever, chills

• Headache

• Muscle pain and joint stiffness

In Michigan, wildlife species that have been diagnosed with Tularemia are muskrats, beavers, cotton-tail rabbits, snowshoe hares, and a Great Horned Owl. The last 2 occurrences in Michigan were in 1981 in beavers and in 1994 in beavers and muskrats.

Infection with F. tularensis has been reported in dogs, cats, pigs, and horses, as well as over 250 other wild and domestic mammals, birds, reptiles and fish. Cattle appear to be resistant. Incubation in animals varies from 1 to 10 days. The disease is characterized by sudden onset of high fever, lethargy, lack of appetite, stiffness, and increased pulse and respiratory rates. Animals that recover from the disease are generally immune to repeat infection

Tularemia is also known
as Rabbit Fever