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occupational health branch​

February 2025 Occupational Health Watch

Preventing Hantavirus Infection in the Workplace

Hantavirus infection is a concern for workers in California whose job sites or duties expose them to rodents or structures where rodents (especially mice) have infested. This includes:

  • Employees of recreational land agencies, such as national, state, or regional parks
  • Campground employees and maintenance workers
  • Staff who work in or around buildings and other closed spaces in rural areas

 In California, deer mice can be infected with Sin Nombre virus, a type of hantavirus that can cause serious illness in people. The virus is found in the urine, droppings, and saliva of infected deer mice. People can become infected when they breathe air in mice-infested areas, including areas where mice have nested and/or left droppings. Particles of hantavirus from mouse nests and droppings can be stirred up into the air when opening or cleaning buildings, cabins, sheds, vehicles, campers, or other closed spaces where deer mice have nested.

Hantavirus pulmonary syndrome (HPS) is one kind of disease that can result from hantavirus infection. HPS is a lung disease, and although it is rare, it can be deadly. Symptoms of HPS are similar to other respiratory infections, including fever, headache, muscle aches, and difficulty breathing. Symptoms of HPS usually develop weeks after breathing air contaminated by infected deer mice. There is no specific treatment or cure for HPS, and death is possible, but early medical care can increase the chances of survival. 

Because hantavirus infection can lead to serious, even deadly disease, it’s important to know how to prevent it.

The best way to prevent hantavirus infection is to keep wild rodents, especially mice, out of buildings and workplaces:

  • Seal up holes (1/4" or larger) and other openings where mice can get in – Learn how
  • Place snap traps to catch any mice (do not use glue traps or live traps) – Learn how

  • Store all food items in rodent-proof containers to keep mice away – Learn how

Working In and Around Areas that Could Be Infested​

If you are planning to enter or inspect a building, vehicle, or other space that has been closed for a period of time, first air out the space for at least 30 minutes (for a building, open windows and doors; for a vehicle, open the hood, doors, and trunk). Do not enter or further inspect the building or space during this time. 

If you are cleaning an area infested by rodents, use protective gear, including rubber or plastic gloves and protective eyewear; clean-up of heavy rodent infestations may warrant additional guidance and the use of respiratory protection. When cleaning, use a ​disinfectant and clean only using wet-cleaning methods, such as with a mop or sponge. Do not sweep or vacuum, as this can stir up hantavirus into the air. Learn more about how to clean up after rodents

Although it is rare in California, hantavirus infection can cause serious illness, and so it requires special attention by employers and staff engaging in work in rodent-infested areas. If you develop fever, difficulty breathing, and have been exposed to rodents or rodent-contaminated materials, see a healthcare provider immediately and tell them about recent work duties or exposure to rodents, especially mice. 

Training and educational resources about hantavirus are available for employees and staff – to learn more, please visit the CDPH Hantavirus Occupational Health Toolkit. ​​

Resources



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