California health officials have reported in hantavirus pulmonary syndrome (HPS) in a Northern California man, prompting reminders of the importance of taking precautions.

Peromyscus maniculatus (deer mouse) Image/CDC
Peromyscus maniculatus (deer mouse)

The most recent case occurred in a patient who was exposed to the virus in Mono County. Most HPS cases have been exposed in the Sierra Nevada or Southern California mountain areas.

“Hantavirus pulmonary syndrome is a rare, but often fatal disease spread by rodents,” said CDPH Director and State Public Health Officer Dr. Karen Smith. “The chances of getting the virus are greatest when entering or cleaning buildings, or other closed spaces, where wild rodents are present.”

HPS is caused by a virus that individuals contract through contact with the urine, droppings or saliva of wild rodents, primarily deer mice. Breathing small particles of mouse urine or droppings that have been stirred up into the air is the most common means of infection. The illness begins with fever, headache, and muscle aches and progresses rapidly to severe difficulty breathing and, in some cases, death.

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To prevent HPS, CDPH recommends the following precautions:
  • Avoid contact with all wild rodents, their droppings, and nesting materials.
  • Before entering an enclosed area that may be infested with rodents, allow it to air out for at least 30 minutes.
  • Do not dry sweep or vacuum areas that rodents have potentially contaminated.
  • Surfaces that rodents may have contaminated with urine or droppings should be made wet with a 10% bleach solution or a commercial disinfectant following label directions before mopping up.
  • Promptly dispose of all cleaning materials when done, and thoroughly wash hands and clothes.
  • Examine the outside of all buildings and seal any holes or other areas that would let rodents get inside.
  • Store all food items securely in rodent-proof containers.

Since HPS was first identified in 1993, there have been 73 hantavirus infections in California and 659 cases nationally. About 30 percent of HPS cases identified in California have been fatal.