STEVE INSKEEP, HOST:
The long Labor Day weekend means camping trips for many people, but some hoping to visit Yosemite National Park are changing their plans because of an outbreak of hantavirus, a rodent-borne disease. State health officials now say two people have died. Another four were infected after visiting the park this summer. As KQED's Lauren Sommer reports, there are new questions about whether the park should have warned visitors about the risk.
LAUREN SOMMER, BYLINE: Anna Bonderenko and her husband were looking forward to taking their two small kids to Yosemite for the first time.
ANNA BONDERENKO: It's one of our favorite spots to go to, and my husband and I hadn't been in a long time.
SOMMER: They booked tent cabins in Yosemite Valley for this weekend with another San Francisco family. Then, they started hearing news reports about hantavirus.
BONDERENKO: It really raised a lot of questions for us since kids tend to touch everything and put their hands in their mouths.
SOMMER: Bonderenko opted for a weekend in Lake Tahoe instead. And it seems like some other potential visitors are following suit.
SCOTT GEDIMAN: There certainly are cancellations, but as people cancel, you know, people are coming without reservations and filling them.
SOMMER: Scott Gediman is a spokesman for Yosemite National Park. At least four park visitors who got hantavirus all stayed in insulated tent cabins in Curry Village. So, earlier this week, the park notified the 1,700 other visitors who also stayed in cabins this summer. State health officials are still investigating the circumstances of the remaining cases. The virus's flu-like symptoms can appear as many as six weeks after exposure. It's spread through contact with mice droppings, so Gediman says they've closed 91 tent cabins to retrofit them.
GEDIMAN: We're putting more wood around the base to eliminate any gaps that rodents may be able to get into. We're shoring up the windows. We're doing a lot of work.
SOMMER: Hantavirus is rare - only about 60 cases in California in the last two decades. It's even more unusual to see a cluster in one place. Epidemiologists are in the park now trying to figure out the reasons for this cluster. Yosemite had two hantavirus cases before this summer, one in 2000 and one in 2010. No one died, but it prompted California's Department of Public Health to get involved.
VICKI KRAMER: We have been to Yosemite on several occasions over the years to trap and test mice and determine if indeed they are carrying the virus.
SOMMER: Dr. Vicki Kramer says statewide, about 14 percent of deer mice have hantavirus. Her department issued recommendations to Yosemite officials two years ago about training staff in cleaning standards, which she says the park did. They also recommended putting up signs in the tent cabins warning visitors to avoid mouse droppings. That didn't happen, says park spokesman Scott Gediman, because the risk was thought to be so low.
GEDIMAN: The point of a national park is for people to experience nature, so we certainly want visitors to know of any potential hazards. But at the same time we don't feel that, you know, signs everywhere warning of everything is either, A, practical or, B, is going to change behavior of visitors.
SOMMER: The park is warning visitors now.
FRANK DYER: It's a Deuter, German pack. Really great pack, very good quality.
SOMMER: At a San Francisco camping store, Frank Dyer says fears about hantavirus haven't come up much as he's helped customers during the pre-Labor Day rush.
DYER: I talked to one customer about backpacking in the area. He says, I'm not worried about it.
SOMMER: At 70 years old, Dyer has been visiting Yosemite for most of his life. He says you have put danger in perspective.
DYER: If you were to climb Half Dome, OK, your chances of dying are probably three million to one over getting, you know, the virus. But you never know.
SOMMER: A good outdoorsman, he says, is always educated about risk.
For NPR News, I'm Lauren Sommer, in San Francisco. Transcript provided by NPR, Copyright NPR.
