Yosemite NP's own web page:

Hantavirus Pulmonary Syndrome Response Continues at Yosemite National Park (August 31, 2012)

Date: August 31, 2012

NPS, CDC Urge Early Detection, Medical Attention for Individuals who Exhibit Symptoms; Health Officials Continue to Monitor New Cases, Protect Public Health

Yosemite National Park continues to scale up its public health response and outreach as a result of six confirmed cases of hantavirus pulmonary syndrome (HPS) in individuals who visited the park in June of this year..... (read more)