Officials at Yosemite National Park have notified 1,700 past visitors they may have been exposed to the rodent-borne disease hantavirus pulmonary syndrome.
It's blamed for the deaths of two people who stayed in cabins at the park. Four people who spent time in Signature Tent Cabins at Curry Village around the same time in June have contracted hantavirus. Two of those affected are expected to survive.
The illness is spread by rodent feces, urine and saliva. The disease can incubate for up to six weeks before flu-like symptoms develop. It's fatal in 30 percent of all cases, and there is no specific treatment.
Rangers have been handing out brochures about hantavirus to guests entering the park. The material precautions they should take.