What is Tularemia and How is it Contracted?

Also known as rabbit fever and deer fly fever, this disease of the Northern hemisphere most often occurs during the summer months and mid-winter and correspond with vectors and hunting season respectively.

The majority of the cases in the United States are found in the south and south-central states.

The disease tularemia is caused by the bacterium Francisella tularensis. This bacterium is found in nature in rabbits, rodents, beavers, squirrels and several domestic and farm animals.

People commonly get infected from the bites of infected ticks (wood, dog) and deer flies.

Hunters are at risk of infection following skinning, dressing and eating infected animals.

Drinking contaminated water has been implicated in tularemia infection. People also contract it through inhaling dust and hay that have rodent feces and carcasses.

There have been cases where people got infected from a domestic cat. It is believed that cats get the organism from contaminated prey and their mouth and claws become infected.

Certain animal associated occupations are also associated with the disease; farmers, veterinarians, sheep herders and shearers.

The disease in people depends on how it’s acquired. After infection, incubation can be a couple of days to weeks, with non-specific symptoms like fever, chills, headache, sore throat and diarrhea.

The way the organism enters the body frequently dictates the disease and degree of systemic involvement. The infection tularemia can be divided into six syndromes:

• Ulceroglandular – This the most common form of tularemia which is characterized by ulcers at the site of the tick bite.

• Glandular – No skin lesions in this infection. Enlarged lymph nodes are present and may require surgical drainage.

• Oculoglandular – This is an infection of the conjunctiva usually by splashes or aerosols.

• Oropharyngeal – The lesion is found in the throat because of ingestion of contaminated water or food.

• Typhoidal – This infection is also due to ingestion of contaminated food and water. This is the only form of tularemia where diarrhea is a prominent characteristic.

• Pneumonic – With a high mortality in this syndrome, this type is most frequently seen in animal associated occupations.

Diagnosis of tularemia is based on detection of antibodies. Culture is possible with appropriate safety precautions and specialized media. Laboratory acquired infections do happen.

Tularemia is treatable with antibiotics (streptomycin and gentamicin).

There is no person to person transmission of this bacterium. F. tularensis is of concern as a possible agent of bioterrorism and biowarfare.

You can prevent tularemia by avoiding insect bites by using repellents and wearing long sleeves. You should also cook wild animals thoroughly before eating.

There is a vaccine for tularemia which is used extensively in Russia, but in the U.S. it is limited to certain high risk occupations.

After infection and recovery of tularemia, typically a long lasting immunity is achieved and reinfection is rare.