A third victim has died from a rare rodent-borne virus contracted in Yosemite National Park, out of eight cases now confirmed with the disease, say authorities at the popular US tourist spot.
The park has issued warnings to some 10 000 people both within the United States and overseas who visited Yosemite between 10 June and late August, and stayed in a specific area of tent cabins.
Previously the number of confirmed cases of hantavirus pulmonary syndrome (HPS) was put at six, with two fatalities.
The park said Thursday eight cases were confirmed and three people had died, adding: "The five remaining individuals are either improving or recovering."
"We want to make sure that visitors have clear information about this rare virus and understand the importance of early medical care," said Yosemite Superintendent Don Neubacher.
"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."
Symptoms of the disease, which can develop with two to six weeks of contracting the virus, include fever, chills, myalgias, cough, headaches and gastrointestinal ailments.
But they can rapidly escalate into serious breathing difficulties and death.
The confirmed cases include six individuals from California, one from Pennsylvania, and one from West Virginia. The types of hantavirus that cause HPS in the United States cannot be transmitted from one person to another.
Some 75 000 tourists a day visit Yosemite, with the majority flocking to Yosemite Valley, which includes Curry Village - where the virus is believed to have been spread by people stayed in scenic "Signature Tent Cabins."
The French health ministry said at the weekend that 53 French tourist families who stayed in the tents were being examined for signs of the illness.
And Britain's Health Protection Agency said that about 100 British travelers may have been exposed, adding that it is working on getting in touch with them.
A 2008 study by California's Public Health Department found that the virus can be found in about one in five of the deer mice in the state's forest service facilities.
Since the disease was identified in 1993, there have been 60 cases in California and 587 nationwide.