"The recent diagnosis of hantavirus pulmonary syndrome (HPS) in six park visitors, two of whom died, has prompted Yosemite National Park to scale up public health response and outreach," park authorities said in a statement.
Up to 10,000 people who were guests in certain lodging cabins might have been exposed to the mouse-borne virus, Yosemite National Park officials said yesterday.
Four more cases of hantavirus have been reported among people who visited Yosemite National Park in California, bringing the total number of cases to six, the California Department of Public Health said Thursday. Two of the six people infected have died.
Those infected visited the park between early June and mid-July, the health department said. Most stayed at the park's popular Curry Village "tent cabins." Yosemite closed the tent cabins indefinitely on Tuesday.
The park sent letters to around 1,700 summer visitors on Monday and Tuesday, explaining that hantavirus cases had been uncovered and that visitors should see their doctors if symptoms surface, park spokesman Scott Gediman said.
Hantavirus pulmonary syndrome is a rare lung disease that kills about a third of those who get infected. Symptoms can include fever, muscle aches and fatigue, though it is not communicable from person to person.
In the United States, the carriers of hantavirus are deer mice, cotton rats, rice rats and white-footed mice.
The virus can be present in the rodents' urine, droppings and saliva, and it is spread to people when they breathe in air contaminated with the virus.
Don Neubacher, Yosemite's superintendent, said that people typically do not fall ill with hantavirus until between one and six weeks after they are exposed.
"The health of our visitors is our paramount concern, and we are making every effort to notify and inform our visitors of any potential illness," Neubacher was quoted as saying by CNN.
Before this year, Yosemite National Park saw one hantavirus case each in 2000 and 2010.
There is no specific treatment for a hantavirus infection, according to health experts, but the earlier a patient is brought to intensive care, the better.
Yosemite National Park covers nearly 1,200 square miles of mountainous terrain in the Sierra Nevada of California.
