Hantavirus pulmonary syndrome has been confirmed in three people in the U.S. — likely acquired at Yosemite National Park in June — the National Park Service announced this week. The syndrome is caused by exposure to urine, feces, or saliva from rodents, particularly deer mice, infected with hantavirus.

Two of the three confirmed cases have died, and a probable fourth case has also been identified.

The national park service is contacting 1700 people who stayed at the Curry Village “Signature Tent Cabins” since mid-June to warn them to seek medical care immediately if they experience early symptoms of hantavirus infection. Early signs include fever, headache, and muscle ache, which can appear 1 to 6 weeks after exposure. These can quickly progress to severe respiratory problems and death.

Source: National Park Service news