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What is tularemia?

Tularemia is a disease caused by the bacteria Francisella tularensis, which infects both animals and humans. Although many wild (hares, rabbits, squirrels, muskrats, beavers, deer) and domestic (sheep, cats) animals have been infected, the rabbit is most often involved with disease outbreaks. The bacteria can also be found in ticks and deerflies.

How is it spread?

The bacteria can be spread to humans through several routes the most common routes being:

• exposure of the skin or mucous membranes with blood or tissue while handling, skinning or dressing infected animals
• the bite of an infected tick
• contact with fluids from infected deer flies or ticks
• handling or eating insufficiently cooked rabbit meat

Less common means of spread are drinking contaminated water, inhaling dust from contaminated soil, or handling contaminated pelts or paws of animals. Tularemia is not spread from person to person. The bacteria are capable of surviving for weeks at low temperatures in water, moist soil, hay, straw, or decaying animal carcasses. It takes exposure to very few organisms to cause disease. It is considered to be a dangerous potential biological weapon because it is so infective and can be spread in different ways.

Tularemia in humans is relatively rare in Ontario. Human cases that have been identified in Grey Bruce have all been associated with trappers or rabbit breeders.

What are the symptoms?

Symptoms vary depending on how the person was exposed. Symptoms generally appear between 1 and 14 days but usually 3 to 5 days after exposure. In cases where a person becomes infected from handling an animal carcass, symptoms can include a slow-growing ulcer at the site where the bacteria entered the skin (usually on the hand) and swollen lymph nodes. If the bacteria is ingested the patient may develop a sore throat, abdominal pain, diarrhea, and vomiting. Breathing in the bacteria may produce fever and a pneumonia-like illness.

How can I treat and prevent it?

Diagnosis is confirmed through isolation of F. tularenis in a blood or tissue sample. A clinical diagnosis is supported by evidence or history of a tick or deerfly bite, exposure to tissues of a known animal host, or exposure to potentially contaminated water. Tularemia can be successfully treated with several types of antibiotics. Long-term immunity will follow recovery of a tularemia infection but re-infection is possible.

Precautions can be taken to protect individuals from tularemia.

• Rubber gloves should be worn when skinning or handling animals, especially rabbits.
• Meat from wild game, especially rabbit and rodent meat, should be cooked thoroughly before eating.
• Wear protective clothing and use insect repellent to avoid bites of flies and ticks.
• Avoid drinking, bathing, swimming, or working in untreated water where infection may be common.

Control of Communicable Diseases in Man Manual (2005)

The Johns Hopkins University, Center for Civilian Biodefense Studies

CDC