Date: July 16, 2019

Mainly cloudy with 60 percent chance of showers and risk of a thunderstorm. Wind southwest 20 km/h gusting to 40 becoming light near midnight. Low 21.

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Environment Canada
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Mice and Hantavirus

This page was reviewed or revised on Thursday, April 16, 2015 1:37 PM

What is Hantavirus Pulmonary Syndrome (HPS)?

Hantavirus is a virus found in rodents, especially in deer mice. It is not a new virus but it has only been detected since 1993 when it was found to be the cause of Hantavirus Pulmonary Syndrome, or HPS. HPS is very rare but a serious illness. The illness was first detected in southwestern U.S.


What is the source of Hantavirus?

Rodents, especially deer mice are the primary carriers of Hantavirus.

The deer mouse (pale grey or reddish brown with white fur on the feet and belly) can be found in all parts of North America with the exception of the tree line in the Yukon in Canada and some of the southeastern states of the U.S.

The habitat of the deer mouse is primarily rural and semi-rural wooded areas, but generally not urban centres. The deer mouse should not be confused with the more common house mouse which is not known to carry Hantavirus.


How is Hantavirus Spread?

Hantavirus is spread to people when they breath in the virus or dust particles contaminated by infected rodent droppings, urine or saliva or by a bite from an infected rodent.

Hantavirus does not cause disease in pets or livestock and is not transmitted from these animals to people.

Hantavirus is not spread by food or water.

Hantavirus is not spread by ticks, fleas, blackflies, mosquitoes and other insects.


What are the symptoms of HPS?

Early symptoms resemble a "flu-like" illness and other viral infections with symptoms of fever, muscle aches and chills.

HPS progresses from these vague symptoms to severe difficulty in breathing.


Is HPS a new disease?

No, HPS is not a new disease. There is no evidence that it is increasing or spreading and it remains an extremely rare disease. What is new is our ability to detect the virus and recognize HPS which was first described in New Mexico during 1993.

Hantavirus has likely been present in deer mice for a long time and may have caused a small number of unrecognized cases of HPS in the past.


How serious is HPS?

HPS is a serious disease. About 50% of known cases have died.


How likely am I to be exposed to Hantavirus?

Most people in Ontario will never be exposed to Hantavirus.

People whose occupation brings them into close contact with rodents, particularly deer mice, (e.g., wildlife biologists and pest control officers) have a greater chance of being exposed to Hantavirus although the chance of developing HPS is extremely remote.

Activities such as sweeping out mouse infested cottages or sheds or other outbuildings left vacant over the winter, or camping directly on uncovered ground in rodent infested areas, may increase the chances of breathing in dust particles contaminated by droppings, urine or saliva from infected rodents.


Is there any treatment of HPS?

Yes, patients with HPS are treated in hospital, often in intensive care. Early treatment of respiratory problems will improve the chances of complete recovery.


How can I protect myself?

Potential sources of the virus can be eliminated by removing rodents from the home. Use spring-loaded traps in infested areas. Rubber or plastic gloves should be worn when handling dead rodents. They should be rinsed in disinfectant (such as laundry bleach) when finished. For disposal of dead mice, place the dead animal in a plastic bag, twist tie it and place it in the regular garbage.

Poison or baits to control rodents can also be used but they are not a good idea unless other control measures have failed. Poisoned animals crawl away to die and their decomposing bodies not only smell bad but they can be hard to find. Poisons can also harm children and pets.

If you're unable to trap mice and they are still around, for help you may want to consult a pest control professional. You should:

  • use approved rodenticides in baits
  • set the bait in an area where there is no access to children or pets
  • place baits inside a covered box with an opening
  • place the covered bait station close to a "runway" (where the mouse droppings are observed)

Measures can be taken to mouse-proof buildings and surrounding area by:

  • sealing any holes on the outside of buildings that might give access to rodents
  • storing food and feed in containers with tight lids.
  • putting pet food and water away at night.

When cleaning up mouse droppings, use a wet method (i.e., wet wiping or mopping with a disinfectant like household bleach. Avoid using dry methods like dusting, sweeping or vacuuming.

If cleaning is done in an unventilated space where there are rodent droppings, a filter-mask should be worn.