Hantavirus
Local, state, national, and global public health partners are currently working together to assess and care for people who were aboard the MV Hondius, a cruise ship that experienced an outbreak of Andes hantavirus. This is a different virus that is native to southern South America. It is the only hantavirus that is spread by close person-to-person contact in addition to being spread by rodents.
Page originally published 5/21/2026.
Hantaviruses are a group of viruses that can cause serious illness and death. In the southwestern United States including California, the virus causing most human disease is called Sin Nombre hantavirus.
- It is spread through the urine, droppings (poop), or saliva of wild rodents, especially deer mice, which live in many parts of California.
- Though human cases of hantavirus in San Diego County are rare, there have been four cases from 2000 through 2025, three of those were exposed to infected rodents outside of San Diego County.
The best way to prevent hantavirus infection is to keep wild
rodents, especially mice, out of the home, workplace, cabin,
shed, car, camper, or other enclosed spaces:
Seal all entry
holes large enough for mice (dime-size or larger).
- Cover or put away pet food dishes when not in use and store pet food in rodent-proof containers.
- Cover all trash cans with rodent-proof lids.
- Use snap traps or poison where there is evidence of mouse activity. Do not use glue traps as it can cause a mouse to urinate when caught.
- Remove woodpiles, old
cars, trash, and debris from property.
If signs of mice or other rodents are found in the home, it’s important to clean up after them safely to reduce chances of getting sick.
- Before cleaning:
- Air out the space that will be cleaned for 30 minutes.
- Use rubber or plastic gloves and a disinfectant or bleach solution made from a mixture of household bleach and water.
- Spray the area with disinfectant or a bleach solution until
very wet and let it soak for at least 5 minutes.
- Use paper towels, a sponge, or mop to clean up the contaminated area.
People can become infected with hantavirus when they breathe in air with the virus.
- Most cases happen when someone spends time in cabins or cleans small indoor areas where infected mice have been long enough to leave droppings
- Hantavirus gets into the air when dried mouse urine, saliva, or droppings (poop) are stirred up. The chances of this happening increase when opening or cleaning buildings in rural areas that have been closed for the winter where deer mice have entered, or for people working, playing, or living in closed spaces where mice are present.
- Andes Virus is the only hantavirus known to spread from person-to-person and that only happens after spending a long time in closeness to someone who is sick with the virus.
In San Diego County, deer mice are the main rodent that carry hantavirus. They usually live in the countryside, desert, and mountain areas. House mice, which often live around people, do not carry hantavirus.
Symptoms may appear 1 to 8 weeks after exposure to rodents or their droppings.
- Early symptoms include chills and fever, fatigue, and muscle aches.
- About half of patients also report headaches or dizziness, nausea, vomiting, or stomach pain, and diarrhea.
- 4-10 days after the initial phase of illness, more serious
symptoms may appear.
- These include coughing, shortness of breath, and tightness in the chest.
- These symptoms are caused if the illness progresses to the more severe form, called Hantavirus Pulmonary Syndrome (HPS). HPS is caused by fluid in the lungs that interferes with breathing. HPS can be very serious, even deadly.
- Hemorrhagic Fever with Renal Syndrome (HFRS) can also occur, which disrupts kidney function.
- If you have a fever, difficulty breathing, and have been exposed to rodents or rodent-contaminated materials, see a doctor right away and tell them about your recent exposure to rodents.
Diagnosing hantavirus in a person who has been infected less than 72 hours is difficult. If the initial test is done before the virus can be found, repeat testing is often done 72 hours after symptoms start.
- There is no treatment for hantavirus infection. People infected with the virus should receive supportive care, including rest, hydration, and treatment of symptoms.
- HPS can cause breathing difficulties and patients may need breathing support, such as intubation (a medical procedure where a tube is placed in the lungs from the mouth to help the patient get oxygen).
- Patients with HFRS may need dialysis to remove toxins from the blood and maintain the right balance of fluids in the body when the kidneys aren't working well.
County of San Diego
- First Hantavirus Detection of 2026 (County News Center – January 16, 2026)
- Hantavirus (Vector Control Program)
- Educational Materials (Schools)
California Department of Public Health
Centers for Disease Control and Prevention
Call the Epidemiology Unit at (619) 692-8499, or send an e-mail, for more information.
Local, state, national, and global public health partners are currently working together to assess and care for people who were aboard the MV Hondius, a cruise ship that experienced an outbreak of Andes hantavirus. This is a different virus that is native to southern South America. It is the only hantavirus that is spread by close person-to-person contact in addition to being spread by rodents.
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