Tularemia is a relatively rare bacterial disease of birds, animals, and people and is found throughout the Northern Hemisphere. It is also called 'rabbit fever.'
What causes tularemia?
Tularemia is caused by Francisella tularensis. There are two strains of this bacteria. Type A generally causes a more severe disease in people. Type B has a more complex life cycle than Type A.
How is F. tularensis transmitted?
In North America, F. tularensis is spread from animal to animal by four different ticks: Dermacentor andersoni, D. variabilis, D. occidentalis, and Amblyomma americanum. Ticks become infected through feeding on infected animals or birds and can transmit the bacteria to another animal any time during the tick's life cycle (2 years). Fleas, like ticks, can transmit tularemia because of their feeding habits. Dogs and cats can also become infected by eating infected rabbits or rodents.
What are the symptoms of tularemia in pets?
Dogs appear to be fairly resistant to the disease and the only symptoms may be loss of appetite, listlessness, and a low fever. Cats are more susceptible and may develop high fevers and swollen lymph nodes. Puppies and kittens are usually more severely affected than older animals.
How is tularemia diagnosed?
A blood test which tests for the animal's antibodies (proteins produced to fight off the infection) to F. tularensis is available. The antibodies may not be detected in the early phase of the disease since it takes some time for the body to make them. As the disease progresses, the antibody level will rise.
Being able to grow F. tularensis in the laboratory from discharges or tissues from the affected animal is the sure way to diagnose the disease.
How is tularemia treated?
The best antibiotic to use to treat tularemia in dogs has not been determined. In people gentamicin and streptomycin are used. Newer antibiotics such as enrofloxacin (Baytril) and ciprofloxacin may be effective.
How is tularemia prevented?
As with other diseases transmitted by fleas or ticks, flea control and tick control are the foundations of prevention. Products which repel and kill ticks and fleas such as those containing permethrins (Bio Spot-Spot On for Dogs and K9 Advantix) are good choices for dogs. For dogs, tick collars containing the active ingredient amitraz are also used, sometimes in conjunction permethrin-containing products in those areas with high tick infestations.
Restricting dogs from killing, eating, or coming into contact with dead rodents and rabbits is also important.
What are the important points to remember about tularemia in people?
People usually develop a lesion at the site of the tick bite which is called an 'indolent ulcer.' Enlarged lymph nodes are a common sign. If the bacteria was ingested (by eating undercooked rabbit, or off of unwashed hands after handling an infected rabbit), intestinal pain, vomiting, and diarrhea can occur. The time from the exposure to the bacteria, either through ingestion or a tick bite, until symptoms occur is generally 3 days. It is important to note that F. tularensis can live in frozen rabbit meat for over 3 years.