Tularemia is a bacterial disease that affects a wide range of animals, including wildlife. Also known as rabbit fever, tularemia is caused by the bacterium Francisella tularensis. It can be transmitted to humans and other animals through direct contact with infected animals, contaminated water or soil, or insect bites. In this article, we will discuss the cause, significance, species affected, distribution, transmission, clinical signs, diagnosis, treatment, and management of tularemia in wildlife.
Tularemia is caused by the bacterium Francisella tularensis, which is a highly infectious, gram-negative bacterium. The bacterium can survive for long periods in water, soil, and animal tissues. It can also survive in ticks, which can transmit the disease to animals and humans. There are several subspecies of the bacterium, and some are more virulent than others.
Tularemia is a significant disease in wildlife because it can cause mortality in various animal species. Infected animals can also serve as a reservoir for the bacterium, which can then be transmitted to humans and other animals. Humans can contract tularemia through contact with infected animals, bites from infected ticks or deer flies, or ingestion of contaminated water or food.
Tularemia can affect a wide range of animal species, including rodents, rabbits, hares, squirrels, beavers, and muskrats. It can also affect domestic animals such as cats, dogs, and livestock. Many bird species are also susceptible to the disease, including wild turkeys, pheasants, and waterfowl.
Tularemia is found throughout North America, Europe, and Asia. The disease is most common in the northern hemisphere, and its distribution is influenced by the presence of tick and mosquito vectors. In the United States, tularemia is most common in the western and midwestern states, but it has also been reported in the eastern states.
Tularemia can be transmitted to animals and humans through a variety of routes. The most common routes of transmission include direct contact with infected animals or their tissues, ingestion of contaminated food or water, and bites from infected ticks or deer flies. The bacterium can also be transmitted through inhalation of contaminated dust or aerosols. It’s more common in areas where rodents and rabbits are densely populated including urban areas with significant food sources.
The clinical signs of tularemia in wildlife can vary depending on the species and the route of infection. In rodents and rabbits, tularemia typically causes sudden death without any clinical signs. In other species, clinical signs can include lethargy, loss of appetite, fever, and swollen lymph nodes. Infected animals may also develop abscesses, ulcers, or nodules at the site of infection.
The diagnosis of tularemia in wildlife can be challenging as the clinical signs can be nonspecific. Diagnostic tests include bacterial culture of blood or tissue samples, serological tests to detect antibodies to the bacterium, and PCR tests to detect the genetic material of the bacterium in animal samples. It is essential to handle suspected cases of tularemia with caution as the bacterium can be highly infectious and potentially fatal to humans.
Antibiotics such as streptomycin, gentamicin, doxycycline, or ciprofloxacin are effective in treating tularemia. Treatment should be initiated as early as possible, and the full course of antibiotics should be completed to ensure complete eradication of the bacteria. Individuals who have been in contact with infected animals or environments should seek medical attention immediately if they develop symptoms.
To prevent tularemia, individuals should take precautions when handling wild animals, especially rabbits, hares, and rodents. They should avoid handling sick or dead animals, and wear gloves when handling animals, especially during skinning and cleaning. Hunters should cook meat thoroughly, and avoid eating raw or undercooked meat. They should also wear gloves while processing animals.
Tularemia is a zoonotic disease that can be transmitted from animals to humans. The disease is caused by the bacteria Francisella tularensis, and is commonly associated with rabbits, hares, and rodents. Although tularemia is rare, it is a serious disease that can be fatal if left untreated. To prevent tularemia, individuals should take precautions when handling wild animals, and seek medical attention if they develop symptoms.
- Jellison WL. Tularemia in North America, 1930-1974. Missoula: University of Montana, 1974.
- Dennis DT, Inglesby TV, Henderson DA, et al. Tularemia as a biological weapon: medical and public health management. JAMA. 2001;285(21):2763-2773.
- Maurin M, Gyuranecz M. Tularaemia: clinical aspects in Europe. Lancet Infect Dis. 2016;16(1):113-124.
- Ellis J, Oyston PC, Green M, Titball RW. Tularemia. Clin Microbiol Rev. 2002;15(4):631-646.
- World Health Organization. Tularemia. https://www.who.int/news-room/questions-and-answers/item/tularemia. Accessed March 31, 2022.
- Keim P, Johansson A, Wagner DM. Molecular epidemiology, evolution, and ecology of Francisella. Ann N Y Acad Sci. 2007;1105:30-66.
- Petersen JM, Schriefer ME. Tularemia: emergence/re-emergence. Vet Res. 2005;36(3):455-467.
- Goethert HK, Telford SR III. Not “out of Nantucket”: emergence of tularemia in the 21st century. N Engl J Med. 2007;357(22):2253-2255.
- Tärnvik A, Chu MC. New approaches to diagnosis and therapy of tularemia. Ann N Y Acad Sci. 2007;1105:378-404.
- U.S. Centers for Disease Control and Prevention. Tularemia. https://www.cdc.gov/tularemia/index.html. Accessed March 31, 2022.