What is tularemia?

Tularemia is a rare and highly infectious disease caused by Francisella tularensis bacteria. It is also called rabbit fever or deer fly fever. The bacteria can infect a wide range of animals, including rabbits and hares, beavers, muskrats, squirrels, and mice, and transmit the disease to people. Cases of tularemia have occurred in household pets, such as dogs, cats, and hamsters.

How common is tularemia?

There are few reported cases of tularemia in the United States (about 100 to 200 cases reported per year), and it is considered a rare disease. However, some cases may be misdiagnosed or go unreported because the symptoms of the disease resemble those of other illnesses. A majority of the confirmed cases have occurred in rural parts of Arkansas, Kansas, Missouri, and Oklahoma. People of all ages can become infected, although males are at higher risk than females.

What causes tularemia?

Bites from ticks, flies, mosquitoes or other insects that carry the Francisella tularensis bacteria can infect humans and animals. Wild animals frequently die after being infected, but people who receive prompt treatment can recover from tularemia. A person infected with tularemia cannot pass the infection along to another person. However, F. tularensis bacteria are very infectious and can survive for long periods in the environment. The main ways that tularemia can be transmitted to humans include:

  • Being bitten by ticks, horse flies, deerflies, or mosquitoes
  • Handling live or dead animals infected with tularemia or their fluids or tissues
  • Eating food or drinking water that is contaminated
  • Inhaling a fine mist or spray (aerosol) or dust particles containing the bacteria

People who work outdoors or pursue outdoor activities such as hunting, trapping, hiking, or camping are at greater risk of contracting tularemia. Laboratory workers who handle biological samples from infected animals or humans can also be at risk unless they take proper safety measures.

What are the symptoms of tularemia?

Symptoms may vary widely, depending on the route of transmission. They can range from mild to severe. In some cases, there are no symptoms, or signs of infection are not noticed. The infection can be life threatening, if untreated. Usually, it takes from three to five days after infection before symptoms appear, but it might take up to two to three weeks.

Symptoms of tularemia may include:

The way that the bacteria enters the body may affect symptoms. They may persist for several weeks. There are several major forms of tularemia, based on the route of transmission.

  • Ulceroglandular: This is the most common type of the infection, usually transmitted by a tick or deer fly bite or by handling an infected animal. A skin ulcer or rash often appears at the area where the bacteria enter the body, and the lymph glands may become swollen or tender.
  • Glandular: This form is similar to the ulceroglandular form, except there is no skin ulcer. It also is transmitted by insect bites or infected animals.
  • Oropharyngeal: Tularemia may enter the body through the mouth if you eat contaminated or undercooked meat or drink contaminated water. You may develop symptoms such as a sore throat, mouth sores, or stomach pain. Nausea, vomiting, or diarrhea may occur.
  • Oculoglandular: Tularemia bacteria can enter the eye through contact with bacteria on the fingers or hands. Hunters who skin and dress meat from rabbits or other animals may be prone to eye infections. Inflammation of the membrane of the eye (conjunctivitis) may cause eye pain, redness, and itching. Swollen lymph glands also may occur.
  • Pneumonic: This is a very serious form of tularemia and may be life-threatening. It affects the lungs. It occurs when people inhale dust or fine droplets containing the bacteria. Symptoms may include coughing, chest pain, and breathing problems. Fluid may build up around the lung, or lung abscesses may occur.
  • Typhoidal: This type is a general form of tularemia whose symptoms include fever, joint pain, and malaise. It may be hard to find out how the infection entered the body. This type affects the bloodstream and major organs. Symptoms can include diarrhea, enlargement of the spleen and liver, and jaundice.

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