As of September 13, the National Park Service (NPS) has announced a total of nine confirmed cases of hantavirus infection in people who recently visited Yosemite National Park. The visitors to Yosemite are residents of: California (7), Pennsylvania (1), and West Virginia (1). Three of the confirmed cases were fatal.
NPS public health officials believe that eight of the nine people with confirmed hantavirus infection were exposed to the virus while staying at the Signature Tent Cabins in Curry Village in Yosemite National Park. The Signature Tent Cabins in Curry Village have been closed. The other park visitor with hantavirus infection was probably exposed to the virus while hiking or staying at the High Sierra Camps, located about 15 miles from Curry Village.
The park is contacting visitors who stayed in the Signature Tent Cabins from mid-June through the end of August, advising them to seek immediate medical attention if they exhibit symptoms of Hantavirus Pulmonary Syndrome (HPS). The park is also providing information about HPS risks and symptoms to visitors who stayed at the High Sierra Camps this summer. On September 12, the park sent an additional notification on HPS to all overnight visitors to the park.
HPS is a severe, sometimes fatal, respiratory disease in humans caused by infection with a hantavirus. Due to the small number of HPS cases, the incubation time is not positively known. However, on the basis of limited information, it appears that symptoms may develop between one and five weeks after exposure to fresh urine, droppings, or saliva of infected rodents. Early symptoms include fatigue, fever and muscle aches, especially in the large muscle groups—thighs, hips, back, and sometimes shoulders. These symptoms are universal. There may also be headaches, dizziness, chills, and abdominal problems, such as nausea, vomiting, diarrhea, and abdominal pain. About half of all HPS patients experience these symptoms. Four to 10 days after the initial phase of illness, the late symptoms of HPS appear. These include coughing and shortness of breath, with the sensation of, as one survivor put it, a "...tight band around my chest and a pillow over my face" as the lungs fill with fluid. HPS can be fatal. It has a mortality rate of 38%.
The CDC and the California Department of Public Health (CDPH) are working with NPS in responding to the situation. The CDPH and Yosemite National Park public health officials are conducting rodent surveys for the purpose of monitoring the numbers deer mice and hantavirus activity in the park's mouse populations.
See the CDC outbreak report