A visitor to Yosemite National Park has recovered after becoming the ninth person diagnosed with a deadly rodent-borne illness blamed for three deaths among those who spent time at the park this summer, officials say.

The California resident was stricken with the hantavirus after visiting Yosemite in early July, National Park Service spokesman John Quinley said Thursday.

Yosemite officials are expanding their efforts to notify visitors to a complex of tent cabins who may have been exposed to a rare but potentially deadly rodent-carried virus. Yosemite officials are expanding their efforts to notify visitors to a complex of tent cabins who may have been exposed to a rare but potentially deadly rodent-carried virus. (DNC Parks and Resorts at Yosemite/Associated Press)

The majority of the cases involved guests at the Signature cabins in Curry Village. One person stayed at multiple High Sierra camps in wilderness areas.

Park officials have sent health warnings to people who stayed at the two locations, advising there may have been a chance of increased exposure.

On Wednesday, officials sent thousands more notifications to reservation holders who booked stays at other locations in the park — locations not associated with any exposures or infections.

Officials said there was no evidence to indicate that people who stayed elsewhere in the park were at increased risk of exposure to hantavirus. The notifications were meant to provide information about the disease and raise awareness, Quinley said.

More than 230,000 overnight guests have stayed in the park since early June.

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.

Health officials said there have been more than 600 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.