Up to 10,000 guests at popular national park may have been exposed to rodent-borne illness for which there is no cure

A West Virginian is the third person to die so far from a rodent-borne illness linked to some tent cabins at Yosemite National Park that has affected eight people in all, health officials said.

Five people are ill from the outbreak reported last week by officials at the California park, who said up to 10,000 guests could have been exposed to hantavirus pulmonary syndrome from sleeping in the cabins since 10 June.

More infections could be reported. Alerts from the US Centers for Dsease Control and Prevention sent to public health agencies, doctors and hospitals have turned up other suspected cases that have not yet been confirmed. This week the European CDC and the World Health Organization issued global alerts for travellers to any country to avoid exposure to rodents.

Dr Rahul Gupta, director of the Kanawha-Charleston health department, declined to release details of the West Virginia victim at a news conference.

Gupta said the victim had visited the park since June but declined to be more specific, citing the family's wish to grieve in private.

The other deaths occurred in California and Pennsylvania. Those that were sickened also were from California and the National Park Service said Wednesday they were either improving or recovering.

Seven of the cases involved guests at the insulated "signature" cabins in the park's historic Curry Village section. The California department of public health said the other case involved someone who stayed in several High Sierra Camps in a different area of Yosemite in July.

Yosemite officials said the cabins have been closed and the park is reaching out to overnight guests who have stayed in the cabins.

Gupta declined to elaborate on whether anyone was travelling with the Kanawha County victim, although he said his department knew of no other cases of hantavirus.

"The time has lapsed in a way that it should not be a concern," Gupta said.

Health officials say the disease isn't spread from person to person. There is no cure for the virus, which can affect people of any age. The disease is carried in the feces, urine and saliva of deer mice and other rodents and carried on airborne particles and dust.

People can be infected by inhaling the virus or by handling infected rodents. Infected people usually have flu-like symptoms including fever, shortness of breath, chills and muscle and body aches. The illness can take six weeks to incubate before rapid acute respiratory and organ failure.

Anyone exhibiting the symptoms must be hospitalized. More than 36% of people who contract the rare illness will die from it.

Health officials said there have been 602 hantavirus cases nationally since the virus was first identified in 1993. The Yosemite cases are unique because they occurred in clusters, while previous cases have been individual exposures.

Park concessionaire Delaware North Company had sent letters and emails to nearly 3,000 people who reserved the cabins between June and August, warning them that they might have been exposed. Because the rooms can hold up to four people, up to 7,000 more visitors might have been exposed, a park spokesman has said.

Yosemite's hantavirus hotline has received thousands of calls about the outbreak. "We want to make sure that visitors have clear information about this rare virus and understand the importance of early medical care," Yosemite superintendent Don Neubacher said Wednesday. "We continue to work closely with state and national public health officials, and we urge visitors who may have been exposed to hantavirus to seek medical attention at the first sign of symptoms."

More than 60 hantavirus cases have been diagnosed in California since 1993. In West Virginia, the densest population of carrier mice are found in higher elevations. Gupta said only three cases of hantavirus have been documented in the state since 1981.