SAN DIEGO — Three deer mice collected during routine monitoring near Mount Laguna earlier this week have tested positive for hantavirus, according to county health officials.

Hantavirus, which is a type of virus spread mainly by rodents, is relatively common in the San Diego region. County officials say as many as 13 cases have been detected during regular testing of the area’s wild rodent population this year so far.

When passed to a human, the virus can be deadly, as there is no cure or vaccine available. However, wild rodents’ natural aversion to human interaction means that exposure to the virus remains quite rare.

According to health officials, people can be exposed when wild rodents invade their living spaces, including homes, garages or sheds.

Infected rodents can “shed” the hantavirus in their urine, feces and saliva, the county says. When this fluid dries, the virus can be spread into the air where people can inhale it.

“People should be particularly aware when doing activities around their homes such as cleaning garages, sheds and outbuildings,” the county wrote in a release.

If anyone finds a wild rodent, nest or other sign of a rodent living in their home, health officials say that a “wet cleaning” method should be used — such as using bleach or other disinfectants, rubber gloves and bags.

Brooms or vacuums should not be used, as those methods could stir the hantavirus into the air where it can be breathed in.

According to the county, signs that a person may have been infected with hantavirus develop roughly one to eight weeks after exposure. Symptoms include:

  • Severe muscle aches.
  • Chills, fever or fatigue.
  • Headache or dizziness.
  • Nausea, vomiting or stomach pain.
  • Difficulty breathing.

Medical attention should be sought immediately if someone believes they have been exposed to hantavirus or are presenting any symptoms of a possible infection.

Health officials also encourage San Diegans to take additional steps in order to avoid hantavirus exposure including:

  • 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 or urine.