All four visitors stayed in Curry Village signature tent cabins. The germs that induce Hanta are transmitted in droppings, urine and saliva of mice and rodents. Park officials suspect that the tent cabins were not sterile enough.
"Hantavirus is a very serious thing and we want to convey the importance of that and the precautions people can take," says Scott Gediman, spokesman for Yosemite National Park. "But we don't want people to think they can't come to Yosemite. Even with the hantavirus we expect to be full. Labor Day is traditionally very busy.
Last summer, climbers in the well known limestone crag of Rifle Colorado contracted Hantavirus.
State health officials have warned anyone experiencing symptoms to see their doctor and tell them that they were camping in Yosemite.
Centers for Disease Control and Prevention's site on hantavirus:http://www.cdc.gov/hantavirus/