Fresno (California): Thousands of people could be at risk from a deadly mouse-borne virus at Yosemite National Park in California, officials said on Friday.
The virus has already claimed two lives, and four other cases of Hantavirus, a rare lung disease, have come to notice.
Park concessionaire Delaware North Co sent letters and e-mails 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 on Friday that means 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`s new hantavirus hotline as visitors frightened about the growing outbreak of 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 Centres 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 hospitalised. 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 worked quickly to disinfect all 400 of the Curry Village cabins when the outbreak first was detected earlier this month. When the outbreak was narrowed to the 91 double-walled insulated cabins, the California Department of Public Health ordered them shut down on Tuesday.
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 faeces, urine and saliva of deer mice and other rodents and carried on airborne aerosol particles and dust.
The hantavirus outbreak occurred despite park officials` efforts to step up protections.
A 2010 report from the state health department warned park officials that rodent inspection efforts should be increased after a visitor to the Tuolumne Meadows area of the park fell ill.
The report revealed 18 percent of mice trapped for testing at various locations around the park were positive for hantavirus.
The park`s new hantavirus policy, enacted on April 25, was designed to provide a safe place, "free from recognised hazards that may cause serious physical harm or death”.
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 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 US 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.
(With Agency inputs)