Tularemia

Overview

Tularemia is an uncommon infection caused by the bacterium Francisella tularensis. It is sometimes called rabbit fever because it often spreads to people through contact with infected wild animals such as rabbits, hares, and rodents. The bacteria can also be passed by the bites of ticks and deer flies, by handling or eating undercooked infected meat, by drinking contaminated water, or by breathing in bacteria from dust, soil, or aerosols, such as when mowing over an infected animal carcass.

Tularemia is highly infectious, meaning very few bacteria are needed to cause illness, and it can be serious if not treated. The form the illness takes depends on how the bacteria entered the body. Because it is rare and its symptoms can resemble other infections, tularemia is sometimes diagnosed late. With prompt antibiotic treatment, however, most people recover well.

Symptoms

Symptoms usually begin three to five days after exposure but can take up to two weeks. Most forms start suddenly with fever, and the specific symptoms depend on how the infection was acquired.

• Sudden high fever, chills, headache, and muscle aches
• A skin ulcer at the site of a bite or contact, with swollen, tender nearby glands
• Swollen, painful lymph nodes
• Red, painful eye with discharge if the bacteria entered through the eye
• Sore throat, mouth ulcers, and swollen neck glands if swallowed
• Cough, chest pain, and trouble breathing if inhaled (the most serious form)

Fatigue and a general feeling of illness are common. The breathing (pneumonic) form is the most dangerous and needs urgent care.

Causes

Tularemia is caused by the bacterium Francisella tularensis, which can reach people in several ways:

• Insect bites: Bites from infected ticks and deer flies.
• Animal contact: Handling, skinning, or being bitten or scratched by infected animals, especially rabbits and rodents.
• Contaminated food or water: Eating undercooked infected meat or drinking contaminated water.
• Inhalation: Breathing in dust or aerosols containing the bacteria, for example while mowing or doing farm or landscaping work.

Tularemia does not spread from person to person.

Risk Factors

• Hunting, trapping, or handling wild animals, especially rabbits and rodents
• Outdoor work and recreation in areas with ticks and deer flies
• Farming, landscaping, or mowing that can stir up contaminated dust
• Laboratory work with the bacteria
• Living in or visiting regions where tularemia occurs

Diagnosis

Tularemia can be hard to diagnose because it is rare and resembles other infections. Telling the doctor about animal contact, insect bites, or outdoor activities is very important.

• History and examination: Looking for an ulcer, swollen glands, and a relevant exposure.
• Blood tests: Antibody tests can show evidence of infection, though they may take time to become positive.
• Cultures and specialized tests: The bacteria can be identified from blood, an ulcer, or other samples, but laboratories must be alerted because the bacteria are hazardous to handle.

Treatment

Tularemia is treated with antibiotics, and early treatment improves recovery.

• Antibiotics: Medicines such as streptomycin, gentamicin, doxycycline, or ciprofloxacin are used depending on the severity and the person. Treatment is often given for one to several weeks.
• Hospital care: Severe cases, especially the pneumonic form, may require hospital treatment and intravenous antibiotics.
• Supportive care: Rest, fluids, and fever control assist recovery.
• Wound care: Skin ulcers and swollen glands are monitored and cared for as needed.

With appropriate antibiotics, most people recover fully, though severe or delayed cases can be life-threatening.

Prevention

• Use insect repellent and protective clothing to avoid tick and fly bites
• Wear gloves when handling wild animals and cook game meat thoroughly
• Avoid handling sick or dead animals, especially rabbits and rodents
• Do not drink untreated water from streams or ponds
• Use a dust mask and avoid mowing over animal carcasses in endemic areas
• Check for and promptly remove attached ticks after being outdoors

When to See a Doctor

See a doctor promptly if you develop a sudden high fever, a skin ulcer, or painfully swollen glands after a tick or fly bite, handling a wild animal, or other possible exposure, and be sure to mention these exposures. Seek emergency care for difficulty breathing, chest pain, severe weakness, confusion, or a high fever that is rapidly worsening, as the pneumonic form of tularemia can become life-threatening and needs urgent antibiotic treatment.

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). Tularemia.
2. Mayo Clinic. Tularemia — Symptoms and causes.
3. MedlinePlus, U.S. National Library of Medicine. Tularemia.
4. World Health Organization (WHO).