Alameda County Public Health Department is actively monitoring and evaluating the occurrence of Andes hantavirus among passengers of the MV Hondius cruise ship. At present, there is no known risk of the Andes hantavirus among Alameda County residents. For providers, this Health Advisory was distributed on May 11, 2026. Additional information can be found here: Hantavirus Infection
Hantaviruses are a family of zoonotic viruses that are shed in the droppings, urine, and saliva of infected rodents. Humans can become infected when they inhale the virus, which can get into the air when rodent droppings, urine, or nesting materials are agitated. The Sin Nombre hantavirus, found in the United States, is spread by infected deer mice and can cause hantavirus pulmonary syndrome (HPS). Andes hantavirus, found in South America, is spread by a long-tailed pygmy rat that is not found in California and is the only type of hantavirus that has demonstrated limited person-to-person spread only with close and prolonged contact to a person who is actively sick.
About Hantavirus Pulmonary Syndrome (HPS)
Hantavirus Pulmonary Syndrome (HPS) is an uncommon respiratory disease caused by hantaviruses. Though rare, HPS can be fatal. Symptoms of HPS usually develop 1-6 weeks after breathing in air contaminated by infected rodents and can include fever, headache, muscle aches and difficulty breathing. There is no specific treatment, but early supportive medical care can increase the chance of survival.
Hantavirus overview (CDPH) Hantavirus overview
Where is Hantavirus found?
Sin Nombre hantavirus is found in all regions of the United States. Deer mice are the primary carriers, along with cotton rats and rice rats in the southeastern states and the white-footed mouse in the Northeast. Potential sites where people may be exposed include areas that offer a habitat for rodents: rural areas, forests, fields, farms, barns, outbuildings, and sheds.
According to CDC, there are several other ways rodents may spread hantavirus to people:
- If a rodent with the virus bites someone, the virus may be spread to that person, but this type of transmission is rare.
- Researchers believe that people may be able to get the virus if they touch something that has been contaminated with rodent urine, droppings, or saliva and then touch their nose or mouth.
- Researchers also suspect people can become sick if they eat food contaminated by urine, droppings, or saliva from an infected rodent.
What is Alameda County doing to control the spread of Hantavirus?
According to Alameda County Vector Control Services District (ACVCSD), deer mice, the reservoir animals of the Sin Nombre, are abundant and widely distributed in Alameda County, especially in rural communities and in housing developments that are built adjacent to wild, open areas. ACVCSD staff has conducted hantavirus surveillance in Anthony Chabot, Del Valle, Redwood, Sunol, and Tilden Regional Parks, as well as in different locations in Oakland, Dublin, Fremont, Pleasanton, and Livermore. Positive antibodies of the Sin Nombre virus have been identified in deer mice. Any person exposed to rodent urine, droppings or nesting material when cleaning an abandoned outhouse, dilapidated barn, horse stable, cabin, or storage shed should take precautions and follow these guidelines: How to Clean Up After Rodents | Healthy Pets, Healthy People | CDC.