Up to 10,000 people who were guests in certain lodging cabins might have been exposed to a deadly mouse-borne virus, Yosemite National Park officials confirmed Friday.
Park concessionaire Delaware North Co. sent letters and emails this week to nearly 3,000 people who reserved the insulated ``Signature'' cabins between June and August, warning them that they might have been exposed.
The cabins hold up to four people, and park spokesman Scott Gediman said Friday that could mean up to 7,000 more visitors might have been exposed to the virus that so far has killed two people and sickened four others.
Meanwhile, more than 1,000 calls a day are coming into Yosemite National Park as visitors frightened about the growing outbreak hantavirus pulmonary syndrome call seeking answers.
On Thursday the California Department of Public Health confirmed that a total of six people have contracted the disease at Yosemite, up from four suspected cases earlier in the week.
Alerts sent to state and county public health agencies, as well as local doctors and hospitals, have turned up other suspected cases that have not yet been confirmed, according to the Centers for Disease Control and Prevention.
The illness that begins as flu-like symptoms can take six weeks to incubate before rapid acute respiratory and organ failure.
There is no cure, and anyone exhibiting the symptoms must be hospitalized. More than 36 percent of people who contract the rare illness will die from it.
All of the victims confirmed so far stayed in the high-end, insulated ``Signature'' tent cabins in the park's historic Curry Village section between mid-June and early July.
Park officials said the double-walled design of those particular cabins made it easy for mice to nest between the walls. The disease is carried in the feces, urine and saliva of deer mice and other rodents and carried on airborne aerosol particles and dust.
The 91 insulated, high-end canvas cabins in the century-old Curry Village are new to the park. They were constructed in 2009 to replace some that had been closed or damaged after parts of Curry Village, which sits below the 3,000-foot (915-meter) Glacier Point promontory, were determined to be in a rock-fall hazard zone.
Upon taking them apart for cleaning, park employees found evidence of mouse nests in the insulation.
In 2011, half of the 24 U.S. hantavirus cases ended in death. But since 1993, when the virus first was identified, the average death rate is 36 percent, according to the CDC. (AP)