deer mouse

Hantavirus is a rare but deadly disease that humans catch from infected rodents. About 30-40% of the people who contract the virus die from it. Knowing about the virus and ways to prevent catching it can help protect you and your family. Hantavirus is an airborne disease. The infection occurs when airborne virus particles from rodent droppings are inhaled. The virus does not spread from person to person.

In the western United States, deer and harvest mice are the main carriers of hantavirus. The disease does not affect the mice themselves. In San Diego County, deer mice are most found in rural areas, the desert and mountains. Avoid contact with all wild rodents, because they may also carry other diseases.  Mice that commonly live with humans are house mice, not deer mice, and do not carry hantavirus.

The Vector Control Program routinely collect blood samples from deer and harvest mice and test it for hantavirus.  If positive results are found, the public is notified on appropriate precautions to take, so they can continue to enjoy outdoor activities without putting themselves at risk of exposure.

Hantavirus in San Diego:

Hantavirus Detection in San Diego County

News Updates:

4 Wild Mice Collected in Campo Area Test Positive for Hantavirus

Symptoms Of Hantavirus

When infection occurs, symptoms may appear 1 to 6 weeks after exposure to rodents or their droppings. Beginning symptoms include:

  • Severe muscle aches
  • Chills and fever
  • Headache or dizziness
  • Difficulty breathing or coughing
  • Respiratory problems or failure
  • Nausea, vomiting, or stomach pain
  • Low blood pressure

People experiencing these symptoms should contact their doctor immediately.


There is no treatment or vaccine for hantavirus.  Medical care can help reduce the symptoms while the infected person is recovering.  


At Risk Activities

Certain activities can put people at more risk for hantavirus:

  • Dry sweeping or using air blowers to clean structures that are not often used
  • Working in barns or out-buildings
  • Living in rodent-infested areas
  • Occupying places that have been empty for a long time
  • Using bare hands to handle grain that could be polluted with rodent droppings
  • Hiking or camping in rodent-infested areas


There are several ways of preventing hantavirus infections. Personal protection measures listed below will help lower exposure to airborne particles when cleaning up rodent droppings.

  • Do not vacuum, sweep or dust
  • Air out unused rooms or buildings that have been empty for a long period of time for 30 minutes by opening doors and windows 
  • Use wet cleaning method
  • Always wear latex or rubber gloves and protective respiratory equipment, such as a face mask
  • Spray dead rodents or droppings with disinfectants before removing
  • Place dead rodents and their nesting material in a sealed plastic bag before throwing them away
  • After cleaning, wash your gloved hands, remove the gloves and dispose of them, and then wash your bare hands as well

Protect Your Home

One of the best ways of preventing exposure to hantavirus is to stop rodents from entering homes or cabins.

  • Seal all holes large enough for mice to get in (dime-size or larger) 
  • Cover or pick up pet food dishes when they are not in use 
  • Store pet food in sealed containers
  • Cover all trash cans with rodent-proof lids
  • Use mouse traps where there is evidence of mouse activity
  • Remove woodpiles, old cars, trash and debris where rodents may live
  • Store hay or firewood at least 100 feet away from buildings
  • Cut grass, weeds and trim bushes within 100 feet of buildings


General Information          Hantavirus Activity Update
CDC Hantavirus Webpage Hantavirus Detection in San Diego County
"The Airborne Menace" Hantavirus Video  
"Mouse Trap" Hantavirus Video  
"Open House" Hantavirus Video  


For More Information On Hantavirus
Or Other Vector-Borne Diseases Contact: 
(858) 694-2888