Information on the following diseases can be found in the Related Disorders section of this report:

• None

The symptoms of tularemia vary greatly among affected individuals. Some individuals may have no apparent symptoms (asymptomatic); others can develop serious complications affecting various organ systems with potentially life-threatening complications if not treated. After infection the period of time it takes symptoms to appear (incubation period) is usually three to five days, but may take as long as two to three weeks.

Most cases of tularemia begin with rapid onset of nonspecific, flu-like symptoms including fever, chills, headaches, muscle pain (myalgia), joint pain (arthralgia), loss of appetite, and a general feeling of ill health (malaise).

Additional symptoms may occur depending upon how a person is infected. Infection through skin (e.g., tick bite or handling of infectious matter) may result in an ulcer or rash on the skin at the point of infection and swollen, painful lymph nodes (lymphadenopathy). These cases may be referred to as ulceroglandular tularemia. In some cases, individuals will have lymphadenopathy without any skin symptoms. These cases are referred to as glandular tularemia. Ulceroglandular and glandular tularemia account for more than 75 percent of cases.

Infection through breathing in (inhalation) the bacterium may result in a persistent cough, sore throat, and, in some cases, may affect the lungs resulting in infection of the lungs (pneumonia), a collection of fluid around the lungs (pleural effusion), and lung abscesses. These cases are referred to as pneumonic tularemia. Eating undercooked, infected animal meat may result in sore throat, nausea, vomiting, diarrhea, and abdominal pain. In rare cases, gastrointestinal bleeding may occur. These cases are referred to as oropharyngeal tularemia.

In extremely rare cases, tularemia may affect the eyes resulting in inflammation of the delicate membrane that lines the eyes (conjunctiva), a condition called conjunctivitis. Conjunctivitis can cause pain, redness, and itching of the eyes. Nearby lymph nodes may be swollen and painful. These cases are referred to oculoglandular tularemia.

Some individuals may develop the typhoidal form of tularemia in which fever, myalgias, and general ill health (malaise) develop without accompanying skin lesions or lymphadenopathy. Because of the lack of obvious symptoms, this form of tularemia is difficult to diagnose.

Tularemia has the potential to affect various organ systems of the body including the central nervous system, heart, and liver resulting in inflammation of the membranes surrounding the brain and spinal cord (meningitis), inflammation of the lining of the heart (endocarditis), and inflammation of the liver (hepatitis). Additional serious complications potentially associated with tularemia include infection of the blood (sepsis) and infection of various bones (osteomyelitis).

Tularemia is caused by the bacterium Francisella tularensis. Most cases occur from being bitten by flies or ticks carrying the disease or from exposure to animals contaminated with the disease. Insects such as ticks and flies acquire the disease from infected animals and transmit it to humans.

Tularemia may be found in a variety of small mammals including rabbits, muskrats, squirrels and beavers. Handling affected animal tissue (e.g., skinning or dressing animal carcasses) or eating insufficiently cooked meat from an infected animal may result in tularemia. Most cases in the United States are related to handling or eating infected rabbits.

Although rare, domestic pets such as dogs and cats may spread tularemia as well. Dogs and cats may come in contact with contaminated animals and, although extremely resistant to the disorder themselves, may spread the disease to human through their saliva and claws.

Tularemia may be also transmitted through the air by breathing in (inhalation) of aerosolized bacteria. Common activities including cutting brush or mowing lawns can aerosolize the bacteria from the environment and cause infection in humans.

Francisella tularensis is an extremely resilient bacterium and able to survive in the environment (e.g., mud, water, or decaying animal carcasses) for weeks and, rarely, direct contact or ingestion of contaminated materials including water or soil may cause tularemia.

No cases of human-to-human transmission have been documented in the medical literature.

Tularemia has gained more attention in recent years because of its potential for use in biological warfare.

Tularemia affects mostly males, probably because of greater exposure opportunities. The disease is rare in the United States with approximately 100-200 new cases reported each year. Some researchers believe that many cases of tularemia often go unreported or misdiagnosed, making it difficult to determine the true frequency of this disease in the general population.

Although tularemia can occur anywhere in the United States, more than half of the cases reported each year occur in rural areas of Arkansas, Missouri, Oklahoma, and Kansas. Tularemia may be found in all parts of Europe and Asia with greater frequency in Siberia and Scandinavian countries.

In Japan, tularemia may be known as yato-byo or Ohara’s disease, after Dr. Ohara who first described a rabbit-associated febrile disease.

Symptoms of the following disorders can be similar to those of tularemia. Comparisons may be useful for a differential diagnosis:

Tularemia must be differentiated from other, more common causes of fever, chronic fatigue, weakness, and other nonspecific flu-like symptoms, and should be highly suspected in individuals in endemic regions who may have been exposed to infected animals.

Diagnosis
A diagnosis of is made by a thorough clinical evaluation, a detailed patient history, identification of characteristic symptoms, and a variety of tests that may include an attempt to isolate the bacteria from blood or body tissue. The most common way a diagnosis of tularemia is confirmed is through specialized blood tests (serologic studies). The body’s immune system creates antibodies against the bacterium. Serologic studies are performed to detect the presence of these antibodies in the blood.

Treatment
Tularemia is treated with antibiotic drugs, which are used to eradicate the bacteria. Antibiotics such as doxycycline and Ciproflaxin can be effective and can be taken by mouth (orally). In severe cases, streptomycin or gentamicin can be given by injection into a muscle or vein.

Other treatment is symptomatic and supportive.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

Research on infectious diseases such as tularemia is ongoing. For more information about these disorders, contact the World Health Organization (WHO) listed in the Resources section below.

TEXTBOOKS
Fauci AS, et al., eds. Harrison's Principles of Internal Medicine, 14th Ed. New York, NY: McGraw-Hill, Inc; 1998:71-4.

Bennett JC, Plum F., eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA: W.B. Saunders Co; 1996:1662-4.

Mandell GL, et al., eds. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 4th ed. New York, NY: Churchill Livingstone Inc; 1995:2060-7.

JOURNAL ARTICLES
Oyston PC, Sjostedt A, Titball RW. Tularemia: bioterrorism defence renews interest in Francisella tularensis. Nat Rev Microbiol. 2004;2:967-78.

Goethert HK, Shani I, Telford SR 3rd. Genotypic diversity of Francisella tularensis infecting Dermacentor variabilis ticks on Martha’s Vineyard, Massachusetts. J Clin Microbiol. 2004;42:4968-73.

Tarnvik A, Priebe HS, Grunow R. Tularaemia in Europe: an epidemiological review. Scad J Infect Dis. 2004:36:350-5.

Cronquist SD. Tularemia: the disease and the weapon. Dermatol Clin. 22:313-20.

Conlan JW. Vaccines against Francisella tularensis – past, present and future. Expert Rev Vaccines. 2004;3:307-14.

Avashia SB, et al., First reported prairie dog-to-human tularemia transmission, Texas, 2002. Emerg Infect Dis. 2004;10:483-6.

Gallagher-Smith M, Kim J, Al-Bawardy R, Josko D. Francisella tularensis: possible agent in bioterrorism. Clin Lab Sci. 2004;17:35-9.

Tarnvik A, Berglund L. Tularemia. Eur Respir J. 2003;21:361-73.

Jensen WA, Kirsch CM. Tularemia. Semin Respir Infect. 2003;18:146-58.

Hornick R. Tularemia Revisited. N Engl J Med. 2001;345:1637-9.

Feldman KA, et al., An outbreak of primary pneumonic tularemia on Martha’s Vineyard. N Engl J Med. 2001;345:1601-6.

FROM THE INTERNET
Edlow JA. Tick-Borne Disease, Tularemia. Emedicine. 2003. Available at: http://www.emedicine.com/emerg/topic591.htm. Accessed on: December 15, 2004.

Centers for Disease Control (CDC) Website. Frequently Asked Questions (FAQ) About Tularemia. Available at: http://www.bt.cdc.gov/agent/tularemia/faq.asp. Accessed on: December 15, 2003.

Center for Biosecurity. University of Pittsburgh Website. Tularemia Fact Sheet. Available at: http://www.upmc-biosecurity.org/pages/agents/tularemia.html. Accessed on: December 15, 2004.

National Institute of Allergy and Infectious Diseases Website. Tularemia. Available at: http://www.niaid.nih.gov/factsheets/tularemia.htm. Accessed on: December 15, 2003.