Tularemia is a reportable disease in Oklahoma. Tularemia is a disease caused by the bacteria Francisella tularensis (F. tularensis), which is found in habitats limited to the Northern hemisphere. The bacteria are commonly found in rabbits, but can also be found in other small mammals such as muskrats, beavers, voles, some domesticated animals (dogs, cats, hamsters) and exotic animals (monkeys, prairie dogs). The bacteria are most commonly spread to humans through the bite of an infected tick, and less commonly from the deer fly (Chrysops discalis). In Oklahoma, the ticks associated with tularemia include the dog tick (Dermacentor variabilis) and the lone star tick (Amblyomma americanum). Tularemia can be transmitted to humans via the skin when handling infected animal tissue. In particular, this can occur when hunting or skinning infected rabbits, muskrats, prairie dogs and other rodents. Many other animals have also been known to become ill with tularemia. Domestic cats are very susceptible to tularemia and have been known to transmit the bacteria to humans. Care should be taken when handling any sick or dead animal. Tularemia is not spread from person-to-person. Tularemia was once commonly known as “rabbit fever.”
The symptoms of tularemia usually begin 3–5 days (range of 1–14 days) after being exposed to the bacteria. Persons with tularemia often develop a sudden influenza-like illness, characterized by fever/chills, body aches, nausea, headache and fatigue. Then they can progress to develop one or more of the 7 different forms of tularemia:
Ulceroglandular – swollen lymph nodes with skin ulcer
Glandular – swollen lymph nodes without skin ulcer
Oculoglandular –swollen lymph nodes and eye infection
Oropharyngeal – swollen lymph nodes and sore throat
Intestinal – abdominal pain, vomiting or diarrhea
Pneumonic – pneumonia and other lung infections
Typhoidal – fever without other symptoms
The form of tularemia that a person develops depends on where the bacteria enter the person’s body. The most common form of tularemia is ulceroglandular, which often causes a skin ulcer at the site of the bite of an infected tick.
Ulcer on finger caused by Tularemia
The diagnosis of tularemia is based upon symptoms and laboratory testing. Blood samples can be tested for antibodies to F. tularensis, and the bacteria can also be cultured from the ulcer site, lymph node or other specimen. Laboratory workers must use extreme caution while working with F. tularensis because the bacteria can be easily spread in laboratory settings.
There are specific antibiotics that can be used for treatment that will reduce the severity of disease. If someone suspects that they were exposed to tularemia, they should see their doctor immediately. Overall, 1-2% of persons with tularemia die due to the disease even with the appropriate antibiotics. Factors associated with a worse outcome include increasing age, serious coexisting medical conditions, symptoms of a month or longer before treatment, and inappropriate antibiotic therapy. Although tularemia can be severe, preventive antibiotic therapy in non-ill persons following a tick bite is not recommended.
What can be done to prevent exposure to tularemia?
- Avoid tick bites. Personal tick bite prevention precautions include:
- Wear light colored clothing to make ticks easier to see.
- Wear long-sleeved shirts and long pants tucked into socks to deprive ticks of attachment sites.
- Wear closed-toe shoes - not sandals.
- Hikers and bikers should stay in the center of trails to avoid grass and brush.
- Check for ticks AT LEAST once per day; particularly along waistbands, in the armpits, and groin area. Don’t forget the back and the hair!
- Use a tick repellent with DEET on skin and clothing according to directions.
- Use a tick repellent with permethrin ON CLOTHING ONLY and as directed by the label.
- Rubber gloves should be worn when skinning or handling animals, especially rabbits.
- Wild rabbit and other game meat should be cooked thoroughly before eating.
External Tularemia Resources: