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Tularemia (Francisella tularensis)

Tularemia is a bacterial disease that can spread to people through bites from ticks or deer flies, handling or consuming infected animals, accidentally swallowing contaminated water, or inhaling contaminated dust. Though typically a wildlife disease, tularemia has been reported in all U.S. states except Hawaii. Affected animals may have sudden onset of fever, weakness, decreased appetite, and reduced mobility. Within a few hours or days, the animal can become stiff and die.

People exposed to tularemia can have a variety of symptoms ranging from fever, chills, headache, and muscle aches to skin ulcers; swollen and painful lymph nodes; inflamed eyes; sore throat; mouth sores and diarrhea. They may also develop pneumonia.

People exposed to an infected animal should be seen by their doctor immediately because treatment works best when started early.

You can reduce your risk of tularemia by handling dead animals with gloves, cooking game meat thoroughly, wearing insect repellent, and when possible, avoiding mowing over dead animals during outside work.

Symptoms

An ulcer caused by Francisella tularensis. Credit: CDC.
An ulcer caused by Francisella tularensis. Credit: CDC.

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)

Prevention

When hiking, camping or working outdoors:

  • Use insect repellents containing 20% to 30% DEET (N,N-diethyl-meta-toluamide), picaridin or IR3535. EPA provides information on the proper use of repellents.
  • 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.

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.

From the Center for Disease Control and Prevention (CDC)

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