DISEASES : Hantavirus

It's a virus that can cause a rare but very serious lung disease called hantavirus pulmonary syndrome (HPS). The virus was first found in people in 1993 but has probably existed for many years.

The first cases were in rural areas of the southwest United States. The U.S. reports less than 35 cases each year, while Canada reports about three cases annually. No cases have been confirmed east of Saskatchewan.

Rodents may carry the virus, especially deer mice. Infected rodents shed the virus in their urine, saliva and droppings (feces).

Deer Mouse

Deer mice are pale grey, with white fur on their stomachs. They live mainly in rural and semi-rural wooded areas. They are not generally found in urban areas.

Health Canada has found the virus in a very small percentage of deer mice tested in Northern Ontario.

Your chances of getting HPS are very low. Only rarely do people exposed to the virus become infected.

People can be exposed to the virus in several ways :

• most often by breathing in infected dust from deer mice droppings or urine;
• being bitten by an infected deer mouse;
• touching any broken skin after contact with infected material.

The virus does not pass from person to person. There is no evidence that the virus is spread through food, water or insects, such as ticks, blackflies and mosquitoes. Pets and livestock do not catch the virus so these animals cannot pass it to people.

Most people in Ontario will never be exposed to hantavirus. People who are in very close contact with deer mice may increase their chances of getting the disease.

Spending time where deer mice live may increase the chance of exposure. These areas include hiking trails, vacant buildings or cottages, barns and fields.

HPS starts with fever, chills, headache and muscle pain. As the disease gets worse it becomes harder to breathe.

If you get these symptoms and shortness of breath within six weeks of exposure to deer mice, see a doctor right away. Symptoms usually start within two weeks. But they can start as early as three days or as late as six weeks after infection.

Early diagnosis helps in successful treatment of symptoms. Research for a vaccine is under way.

The easiest way is to limit your contact with deer mice and their droppings, urine or saliva. They are attracted to areas where they can find food, water and shelter. It's wise to follow these tips anywhere there are large numbers of mice.

• Always store food, water and garbage in metal or heavy plastic containers with tight-fitting lids. Do not leave pet food or water out overnight.
• Seal holes around doors, windows and roofs with steel wool or cement. To discourage digging and nesting, place gravel around the base of the building.
• Remove any abandoned vehicles, old tires or cast-off furniture from your property. Cut back thick bush and keep grass short. Keep woodpiles, hay and trash cans off the ground and away from your home.
• When hiking or camping, use a ground cover or a tent with a floor. Try to avoid areas where there are rodent burrows or droppings. It's always wise to use bottled or disinfected water.

• Set traps indoors. Douse dead mice, used traps and nests with household disinfectant or diluted bleach. Household bleach is diluted by mixing 1 tablespoon of the bleach in one litre of water (or 4 tablespoons of bleach for each gallon of water).
• Always use rubber or plastic gloves when handling dead rodents and other materials. Put them inside a plastic bag. Seal the bag, then put it in a sealed garbage can. Or bury it.
• Rinse gloves in disinfectant or diluted bleach before you remove them. Wash gloves and hands in hot soapy water.
• Always wear rubber gloves when cleaning up signs of mice. Open windows/doors for a half-hour before and after cleaning to air out the area.
• Wet floors to minimize dust. Damp-mop and wash floors with soap, water and disinfectant. Do not vacuum or sweep bare floors before mopping.
• Wear a breathing mask if the area is poorly ventilated. Wash countertops, drawers and cupboards with disinfectant. Wash any clothing or bedding contaminated with droppings. Dry them in the sun or in a hot dryer.
• After clean-up, wash hands and face well before eating, drinking or smoking.
• Don't attract mice. Always clean up spilled food, and wash dishes right away.

Contact your local public health unit for more information.