More than 230,000 people who have stayed overnight anywhere in Yosemite National Park this summer are being notified of their possible exposure to a potentially deadly virus spread by rodents.
Park officials said this week that they were massively expanding their outreach to all of those who lodged or camped in the popular Northern California park during a widely publicized outbreak of the hantavirus, which has killed three people.
More than 3,000 visitors who stayed in historic tent cabins at Curry Village in Yosemite Valley and at the High Sierra Camps had already been notified that they may have been exposed.
The virus can be contracted when humans inhale infected urine, droppings or saliva from deer mice that bear the disease. Not all patients infected with the virus progress to the potentially fatal respiratory disease Hantavirus Pulmonary Syndrome.
Nationwide, about 12 percent of deer mice carry hantavirus, according to the park. The disease is most common in rural areas and has been contracted by 602 people nationwide since it was first discovered in 1993, most of them in the southwest.
In mid-August, the park announced that two victims of the virus had been found, and one of them had died. Since then, two more patients have died and the outbreak has led some travelers to cancel their trips to one of the country's most-visited national parks.
On Wednesday, the park said it would notify by email more than 230,000 visitors who stayed in any lodging in the park since June.
"Your recent overnight visit to Yosemite did not include a stay in lodging where the known hantavirus infections might have occurred; however, we wanted to take this opportunity to increase public awareness about hantavirus," the park's notification email reads.
Then, on Thursday, the park said a ninth person had contracted the disease and recovered. That victim was from California and was believed to have stayed in the Curry Village tent cabins, authorities said. The individual recovered after experiencing only mild symptoms, officials said.
At the recommendation of the California Department of Public Health, the national park closed those tent cabins on Aug. 28 for an indefinite time.
The eighth-announced victim was thought to have been exposed while staying in tent cabins in Yosemite's High Country – some 15 miles from Curry Village and at a higher elevation. That person also recovered, authorities said.
Hantavirus symptoms can begin between one and five weeks after exposure, and include fatigue, fever, chills, and muscle aches. About half of victims also get headaches, nausea, vomiting, dizziness and stomach pain. Symptoms then typically progress rapidly to include coughing and difficulty breathing.
Those who think they may have been exposed to hantavirus and have such symptoms are urged to seek early medical attention, which "greatly increases the chance of survival," the park said.
- Yosemite National Park hantavirus alert page
- Park FAQ on hantavirus outbreak
- Centers for Disease Control and Prevention's hantavirus page