Hantavirus pulmonary syndrome has now been confirmed in eight people who visited Yosemite National Park this summer, three of whom have died, the National Park Service has announced.

Seven of the cases stayed in the park’s Signature Tent Cabins in Curry Village; the eighth lodged in multiple High Sierra Camps — a more remote area of the park. Accordingly, officials have expanded the initial hantavirus warning to a total of 22,000 Yosemite visitors who may have been exposed to the rodent-borne disease since June 10.

The National Park Service notes that the kinds of hantavirus that cause hantavirus pulmonary syndrome in the U.S. cannot be passed from person to person.

Source: National Park Service hantavirus update