(CBS News) YOSEMITE NATIONAL PARK, Calif. - There has been an outbreak of hantavirus, a deadly disease spread by rodents. More than 22,000 people who visited Yosemite National Park since June have now been warned they should get tested. There have been eight confirmed cases and three people have died. One of the survivors said the warnings came too late.
The majestic beauty of Yosemite National Park in California draws 4 million tourists every year. Now every visitor is being warned that along with dramatic scenery could come exposure to the potentially deadly hantavirus.
Hantavirus is contracted by breathing airborne particles from droppings and urine of infected deer mice. One to six weeks after exposure, victims suffer flu-like symptoms. Lungs can become filled with fluid; breathing can become difficult. More than one-third of victims die from the disease.
Nicole Lapeyrade fell seriously ill with hantavirus after a July trip to Yosemite with her family, including five children. She's heard nothing from the park about the disease -- not before her visit, not after she reported the results of her blood test.
"I'm disappointed about the park's lack of response," she said, "and the seemingly lack of concern for the public welfare."
Since the outbreak, the park has closed down 91 tents where most of the victims stayed. It's patching up and cleaning up the rest.
Twice in the last five years -- after researchers noticed a spike in infected mice, and after a woman fell ill -- the California Department of Public Health urged Yosemite to warn visitors about hantavirus. The park launched an aggressive information campaign just two weeks ago.
"As a park, we feel that we've taken appropriate steps to notify individuals," said Kari Cobb, a Yosemite park ranger.
"It wasn't something that we posted in our most prevalent places," she added. "In the last 100 years, we've literally only had two cases aside from this cluster of eight. It wasn't something that Public Health thought was a major problem and it wasn't something that the park thought was a major problem."
One case of hantavirus is rare; eight cases in one location is unprecedented. One theory is that tourists and all their food are feeding a population boom of infected mice.