Potential case of rare and deadly hantavirus investigated at Bay Area prison

Officials at San Quentin Rehabilitation Center confirmed they are investigating a potential case of hantavirus after an individual exhibited symptoms associated with the deadly respiratory disease. 

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Tests are being sent to the California Department of Public Health and the U.S. Centers for Disease Control and Prevention to confirm whether the person is infected with the rare virus. 

Neither the condition of the individual nor their identity has been released yet. The facility where they are housed at the Bay Area prison has been decontaminated, according to the California Department of Corrections and Rehabilitation.

“The health and safety of the incarcerated population and staff remain CDCR’s top priority,” department spokesperson Kyle Buis said in a statement to SFGATE. 

Hantavirus is a rare and extremely dangerous virus that can cause a disease with a fatality rate of around 35% in the U.S., according to the U.S. Centers for Disease Control and Prevention. 

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, called hantavirus a “stealth infection” because early symptoms are often generic flu-like symptoms, including fever, sore throat and body aches. 

“People think it’s just a common viral infection,” Schaffner told SFGATE. “… They think they’re going to get better in a day or so, and then this goes on for maybe two, three days, and then they can crash.” 

Advanced symptoms of disease can include fluid-filled lungs and a drop in platelets, leading to bleeding. 

There’s no vaccine and no cure other than supportive care. 

In the U.S., hantavirus is transmitted via rodents like mice and rats that harbor the bacteria and can spread it via their feces and urine. Schaffner explained people can get sick if they breathe in aerosolized material from the rodents. Often, he said, people are sickened after finding the animals nesting in a home shed or garage. 

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“They’re actually cleaning it up, and that’s when the exposure often occurs,” Schaffner explained.

Recently, an outbreak of the Andes strain of the virus aboard a cruise ship in the Atlantic Ocean made international headlines after eight people were infected and three died. That rare strain is the only known hantavirus to spread person to person, but it is not native to the U.S. 

In the U.S., the disease is most common in Western states, with Arizona, Colorado and New Mexico reporting the highest number of cases. Mammoth Lakes, a mountain town in California’s Eastern Sierra, saw an unprecedented hantavirus outbreak in 2025 that killed three people. 

Dr. Monica Gandhi, an infectious disease expert at UC San Francisco, said that the cruise ship outbreak is unlikely to be involved in this potential case since all passengers returned to the U.S. were monitored for 42 days to ensure they did not develop the disease. 

If confirmed, Gandhi said, a hantavirus case at San Quentin would be unusual, since the disease is more common in desert, arid-like climates. She said physicians may consider testing for hantavirus if a seemingly healthy person develops unusual and severe symptoms such as fluid-filled lungs and unusual bleeding coupled with an exposure to rodents.

“We always have to think about different viruses,” she said. 

Editor’s note: This story was updated at 3:50 p.m., June 11, to correct information about the fatality rate associated with hantavirus.