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Deer Mice Test Positive for Hantavirus


Last updated 2/15/2024 at 10:34am

Three deer mice collected near Mount Laguna during routine monitoring on November 1 have tested positive for hantavirus.

Hantavirus in wild rodents is relatively common in San Diego County. This is the 13th routine detection of hantavirus in the region this year. However, because wild rodents naturally avoid people, human exposure to the virus is rare. Still, County officials advise people to be careful around wild rodents as there is no cure or vaccine for hantavirus.

The last reported deer mouse finding close to Borrego Springs was in Warner Springs on July 25, 2019, and three deer mice and one brush mouse did test positive for the virus in Santa Ysabel that year. Borrego Springs and Julian remain clear so far.

Although the hantavirus is not uncommon in the rural and undeveloped areas of the county, people are not likely to be exposed to it so long as they keep wild rodents out of their living spaces and structures like their homes, garages, sheds, and cabins. Wild rodents, wild mice specifically, are the leading carriers of the virus.

Officials remind everyone the hantavirus is an airborne virus, is not passed from one person to another, nor caught by touching an infected rodent.

People can be exposed to the virus when wild rodents invade their living areas – such as homes, garages and sheds. People should be particularly aware when doing activities around their homes such as cleaning garages, sheds and outbuildings.

Infected rodents shed the hantavirus in their urine, feces and saliva. Once the matter dries, the hantavirus can be stirred into the air where people can inhale the virus.

If people find wild rodents, nests or other signs of rodents in their living spaces, they should always use “wet cleaning” methods – using bleach or other disinfectants, rubber gloves and bags. They should NOT sweep or vacuum, which could stir hantavirus into the air where it could be inhaled.


Symptoms of hantavirus usually develop between 1-8 weeks after exposure and include:

Severe muscle aches.

Chills, fever or fatigue.

Headache or dizziness.

Nausea, vomiting or stomach pain.

Difficulty breathing.

If you think that you may have been exposed to hantavirus, seek medical attention immediately.

Avoiding Exposure to Hantavirus

Seal up all external holes in homes, garages, and sheds larger than a dime to keep rodents from getting in.

Eliminate rodent infestations immediately.

Avoid rodent-infested areas and do not stir up dust or materials that may be contaminated with rodent poop and urine.

Clean up rodent poop and urine using the “wet cleaning” methods described below.

Wet cleaning methods

Do not sweep or vacuum infested areas.

Ventilate the affected area by opening doors and windows for at least 30 minutes before starting to clean.

Use rubber gloves. Spray a 10% bleach solution or other disinfectants onto dead rodents, rodent poop, nests, contaminated traps and surrounding areas, then let the disinfectant stand for at least 15 minutes before cleaning.

Clean with a sponge or a mop that has been soaked in disinfectant.

Place disinfected rodents and debris into two plastic bags, seal them and discard them in the trash.

Wash gloves in a bleach solution, then soap and water, and dispose of them using the same double-bag method.

Thoroughly wash your hands with soap and water.

For more information, contact the County Department of Environmental Health and Quality at (858) 694-2888 or visit the hantavirus web page.