Tularemia is a disease of animals and humans caused by the bacterium Francisella tularensis. Rabbits, hares, and rodents are especially susceptible and often die in large numbers during outbreaks. Humans can become infected through several routes, including:

• Tick and deer fly bites
• Skin contact with infected animals
• Ingestion of contaminated water
• Inhalation of contaminated aerosols or agricultural dusts
• Laboratory exposure

In addition, humans could be exposed as a result of bioterrorism.

Symptoms vary depending on the route of infection. Although tularemia can be life-threatening, most infections can be treated successfully with antibiotics.

Steps to prevent tularemia include:

• Use of insect repellent
• Wearing gloves when handling sick or dead animals
• Avoiding mowing over dead animals

In the United States, naturally occurring infections have been reported from all states except Hawaii.

What is tularemia?

Tularemia is a potentially serious illness that occurs naturally in the United States. It is caused by the bacterium Francisella tularensis found in animals (especially rodents, rabbits, and hares).

What are the symptoms of tularemia?

Symptoms of tularemia may include:

• Sudden fever
• Chills
• Headaches
• Diarrhea
• Muscle aches
• Joint pain
• Dry cough
• Progressive weakness

People can also develop pneumonia with chest pain, cough, and difficulty breathing.

Other symptoms of tularemia depend on how a person was exposed to the tularemia bacteria. These symptoms can include ulcers on the skin or mouth, swollen and painful lymph glands, swollen and painful eyes, and a sore throat.

How does tularemia spread?

People can get tularemia many different ways:

• Being bitten by an infected tick, deerfly or other insect
• Handling infected animal carcasses
• Eating or drinking contaminated food or water
• Breathing in the bacteria, F. tularensis

Tularemia is not known to be spread from person to person. People who have tularemia do not need to be isolated. People who have been exposed to the tularemia bacteria should be treated as soon as possible. The disease can be fatal if it is not treated with the right antibiotics.

How soon do infected people get sick?

Symptoms usually appear 3 to 5 days after exposure to the bacteria, but can take as long as 14 days.

What should I do if I think I have tularemia?

Consult your doctor at the first sign of illness. Be sure to let the doctor know if you are pregnant or have a weakened immune system.

How is tularemia treated?

Your doctor will most likely prescribe antibiotics, which must be taken as directed by your doctor to ensure the best possible result. Let your doctor know if you have any allergy to antibiotics.

A vaccine for tularemia is under review by the Food and Drug Administration and is not currently available in the United States.

What can I do to prevent becoming infected with tularemia?

Tularemia occurs naturally in many parts of the United States. Use insect repellent containing DEET on your skin, or treat clothing with repellent containing permethrin, to prevent insect bites. Use care and wear gloves when handling sick or dead animals. Be sure to cook your food thoroughly and that your water is from a safe source. Note any change in the behavior of your pets (especially rodents, rabbits, and hares) or livestock, and consult a veterinarian if they develop unusual symptoms.

Can tularemia be used as a weapon?

Francisella tularensis is very infectious. A small number (10-50 or so organisms) can cause disease. If F. tularensis were used as a weapon, the bacteria would likely be made airborne for exposure by inhalation. People who inhale an infectious aerosol would generally experience severe respiratory illness, including life-threatening pneumonia and systemic infection, if they are not treated. The bacteria that cause tularemia occur widely in nature and could be isolated and grown in quantity in a laboratory, although manufacturing an effective aerosol weapon would require considerable sophistication.

What is CDC doing about tularemia?

CDC operates a national program for research into the epidemiology and natural ecology of tularemia as well as the development of improved diagnostic tests. CDC serves as a reference laboratory for the United States and a World Health Organization (WHO) collaborating center for tularemia. Additional things CDC is doing related to bioterrorism preparedness include stockpiling antibiotics to treat infected or exposed people and educational programs for health professionals, the public and the media.

The bacterium that causes tularemia is highly infectious and can enter the human body through the skin, eyes, mouth, or lungs. Symptoms of infection vary depending on the route of entry. Usual sources of infection are described below. Transmission of tularemia from person to person has not been reported.

Tick or deer fly bites

In the United States, ticks that transmit tularemia to humans include the dog tick (Dermacentor variabilis), the wood tick (Dermacentor andersoni), and the lone star tick (Amblyomma americanum). Deer flies (Chrysops spp.) have been shown to transmit tularemia in the western United States. Infections due to tick and deer fly bites usually take the form of ulceroglandular or glandular tularemia.

Handling infected animals

F. tularensis bacteria can be transmitted to humans via the skin when handling infected animal tissue. In particular, this can occur when hunting or skinning infected rabbits, muskrats, prairie dogs and other rodents. Many other animals have also been known to become ill with tularemia. Domestic cats are very susceptible to tularemia and have been known to transmit the bacteria to humans. Care should be taken when handling any sick or dead animal. Outbreaks of tularemia have occurred among hamsters purchased from pet stores. At least one child in the U.S. has developed tularemia after being bitten by a pet hamster. Infection due to handling animals can result in glandular, ulceroglandular and oculoglandular tularemia. Oropharyngeal tularemia can result from eating under-cooked meat of infected animals.

Other exposures

Humans can acquire tularemia by inhaling dust or aerosols contaminated with F. tularensis bacteria. This can occur during farming or landscaping activities, especially when machinery (e.g. tractors or mowers) runs over infected animals or carcasses. Although rare, this type of exposure can result in pneumonic tularemia, one of the most severe forms of the disease. Water can also become contaminated with the bacteria through contact with infected animals. Humans who drink contaminated water that has not been treated may contract oropharyngeal tularemia. This mode of transmission appears to be much more common in Europe than the U.S.

The signs and symptoms of tularemia vary depending on how the bacteria enter the body. Illness ranges from mild to life-threatening. All forms are accompanied by fever, which can be as high as 104 °F. Main forms of this disease are listed below:

• Ulceroglandular This is the most common form of tularemia and usually occurs following a tick or deer fly bite or after handing of an infected animal. A skin ulcer appears at the site where the bacteria entered the body. The ulcer is accompanied by swelling of regional lymph glands, usually in the armpit or groin.

• Glandular Similar to ulceroglandular tularemia but without an ulcer. Also generally acquired through the bite of an infected tick or deer fly or from handling sick or dead animals.
• Oculoglandular This form occurs when the bacteria enter through the eye. This can occur when a person is butchering an infected animal and touches his or her eyes. Symptoms include irritation and inflammation of the eye and swelling of lymph glands in front of the ear.
• Oropharyngeal This form results from eating or drinking contaminated food or water. Patients with orophyangeal tularemia may have sore throat, mouth ulcers, tonsillitis, and swelling of lymph glands in the neck.
• Pneumonic This is the most serious form of tularemia. Symptoms include cough, chest pain, and difficulty breathing. This form results from breathing dusts or aerosols containing the organism. It can also occur when other forms of tularemia (e.g. ulceroglandular) are left untreated and the bacteria spread through the bloodstream to the lungs.
• Typhoidal This form is characterized by any combination of the general symptoms (without the localizing symptoms of other syndromes)

Tularemia can be difficult to diagnose. It is a rare disease, and the symptoms can be mistaken for other, more common, illnesses. For this reason, it is important to share with your health care provider any likely exposures, such as tick and deer fly bites, or contact with sick or dead animals.

Blood tests and cultures can help confirm the diagnosis. Antibiotics used to treat tularemia include streptomycin, gentamicin, doxycycline, and ciprofloxacin. Treatment usually lasts 10 to 21 days depending on the stage of illness and the medication used. Although symptoms may last for several weeks, most patients completely recover.

Antibiotics used to treat tularemia include streptomycin, gentamicin, doxycycline, and ciprofloxacin. Treatment usually lasts 10 to 21 days. Although symptoms may last for several weeks, most treated patients make a full recovery. Untreated tularemia infections are fatal in 5-15% of cases.

When hiking, camping or working outdoors:

• Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone.
• Wear long pants, long sleeves, and long socks to keep ticks and deer flies off your skin.
• Remove attached ticks promptly with fine-tipped tweezers.
• Don’t drink untreated surface water.

When mowing or landscaping:

• Don’t mow over sick or dead animals. When possible, check the area for carcasses prior to mowing.
• Use of masks during mowing and other landscaping activities may reduce your risk of inhaling the bacteria, but this has not been studied.

If you hunt, trap or skin animals:

• Use gloves when handling animals, especially rabbits, muskrats, prairie dogs, and other rodents.
• Cook game meat thoroughly before eating.

Until recently, a vaccine has been available to protect laboratorians routinely working with Francisella tularensis. This vaccine is currently under review by the US Food and Drug Administration (FDA) and is not generally available in the United States.

When treated promptly, tularemia seldom has long-term effects. If it is untreated or if treatment is delayed, the infection may affect any part of the body, causing:

• Lung problems, such as pneumonia
• Damage to the cornea of the eye
• Enlargement of the heart
• Infection of the spinal fluid or fluid surrounding the brain, such as meningitis
• Bone infection (osteomyelitis)

If untreated, severe forms of tularemia can be fatal.