(AP) YOSEMITE NATIONAL PARK, Calif. -- One of the most popular U.S. national parks on Tuesday warned 1,700 recent visitors they may have been exposed to a rare, rodent-borne disease after a second person died after visiting Yosemite National Park this summer.
The email alerts warned of hantavirus pulmonary syndrome, which can be carried in the urine, saliva and feces of infected deer mice.
All of the at-risk visitors had stayed in the "Signature Tent Cabins" in the park's Curry Village.
Health officials learned this weekend of the second hantavirus death, which killed a person who visited the park in June, spokesman Scott Gediman said in a statement.
Another case of the illness has been confirmed, and a fourth is being investigated. The first death was reported earlier this month.
Yosemite officials said Monday that the four visitors might have been exposed while vacationing at Curry Village. They warned those who stayed in the village's tent cabins from mid-June through the end of August to beware of any symptoms of hantavirus, which can include fever, aches, dizziness and chills.
Of the 587 documented U.S. cases since the virus was identified in 1993, about one-third proved fatal. There is no specific treatment for the virus.
Federal health officials say symptoms may develop up to five weeks after exposure to urine, droppings, or saliva of infected rodents, and Yosemite advised visitors to watch for symptoms for up to six weeks.
Officials said thousands of people visit the park every month, so it would be impossible to track everyone who had set foot in Curry Village. It was not clear how many people stayed in the cabins in the period for which park officials issued the warning.
Gediman said contractors are working on the cabins to protect park-goers.
"They're doing everything they can to eliminate areas where mice can get into the cabins," Gediman told the San Francisco Chronicle. "This was never because the cabins were dirty, it was never because we didn't take care of them. This is just because approximately 20 percent of all deer mice are infected with hantavirus. And they're here in Yosemite Valley."
This year's deaths mark the first such deaths among park visitors, although two others were stricken in a more remote area in 2000 and 2010, officials said.