Deerfly fever

Definition

Tularemia is an infection common in wild rodents. It is caused by the organism Francisella tularensis. Tularemia is transmitted to humans by contact with infected animal tissues or by ticks, biting flies, and mosquitoes.

Alternative Names

Causes

Humans can contract tularemia in the following ways:

• Direct contact, through a break in the skin, with an infected animal or its carcass
• The bite of an infected tick, horsefly, or mosquito
• Eating infected meat (rare)

Endemic areas (areas where the disorder occurs most commonly) include North America and parts of Europe and Asia. The illness may continue for several weeks after symptoms begin.

Some people may develop an atypical pneumonia after infection. Risk factors include recent exposure to rabbits or a recent tick bite. The disease is very rare in the United States.

Francisella tularensis is considered a potential bioterrorism agent. An aerosol release would be a possible method of infection, and would result in pneumonia cases, beginning 1 - 10 days after exposure.

Symptoms

• Chills
• Enlarged lymph nodes of the groin or armpits
• Fever
• Headache
• Joint stiffness
• Muscle pains
• Possible conjunctivitis
• Red spot on the skin, enlarging to an ulcer
• Shortness of breath
• Sweating
• Weight loss

Exams and Tests

• Serology for tularemia
• PCR (polymerase chain reaction) test of a sample from an ulcer
• Blood culture for tularemia
• Chest x-ray

This disease may also alter the results of febrile/cold agglutinins.

Treatment

The goal of treatment is to cure the infection with antibiotic treatment. Streptomycin and tetracycline are commonly used to treat this infection. Once daily gentamycin treatment has been tried with excellent results as an alternative therapy to streptomycin, though only a few cases have been studied to date.

Note: oral tetracycline is usually not prescribed for children until after all their permanent teeth have erupted. It can permanently discolor teeth that are still forming.

Outlook (Prognosis)

Tularemia is fatal in about 5% of untreated cases, and in less than 1% of treated cases.

Possible Complications

• Meningitis
• Osteomyelitis
• Pericarditis
• Pneumonia

When to Contact a Medical Professional

Call your health care provider if symptoms develop after a rodent bite, tick bite, or exposure to the flesh of a wild animal.

Prevention

A vaccine is recommended for people at high risk (trappers, hunters, and laboratory workers who work with the organism).

Eliasson H, Broman T, Forsman M, Back E. Tularemia: current epidemiology and disease management. Infect Dis Clin North Am. 2006. Jun;20(2):289-311, ix.

Hassoun A, Spera R, Dunkel J. Tularemia and Once-Daily Gentamicin. Antimicrobial Agents and Chemotherapy 2006; 50(2),824.

Cronquist SD. Tularemia: the disease and the weapon. Dermatol Clin. 2004; 22(3): 313-20, vi-vii.

Long SS, Pickering LK, Prober CG. Principles and Practice of Pediatric Infectious Diseases. 2nd ed. New York, NY: Elsevier; 2003:917.

Cohen J, Powderly WG. Infectious Diseases. 2nd ed. New York, NY: Elsevier; 2004:1649-1653.

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