Yosemite Confirms 2 Cases of Norovirus, Investigating 170 Reports of Illness

Yosemite National Park is investigating about 170 reports of gastrointestinal illnesses and has confirmed two cases of norovirus, officials say.

The National Park Service began investigating after visitors and employees started reporting falling ill — most of them in early January. Most of the cases are consistent with norovirus, although some might have had food poisoning or the flu, the park said.

"We've had very few (cases) the last week or so," park spokesman Scott Gediman said Thursday. "We're hoping that we're over the hump."

Norovirus is highly contagious and can be spread through direct contact with an infected person, touching a contaminated surface or eating or drinking contaminated food. It can cause vomiting and diarrhea and its symptoms are especially severe for elderly people, young children and those with health issues. Symptoms surface within 12-48 hours after exposure.

Each year, norovirus causes 19 to 21 million cases of acute gastroenteritis on average in the U.S. and is the leading cause of foodborne illness nationwide, according to the Centers for Disease Control and Prevention.

Park officials and medical staff with the National Park Service Office of Public Health are looking into the circumstances surrounding the current illnesses and are interviewing affected people, but haven't determined the origin of the outbreak or whether people who got sick contracted something inside or outside of the park.

Most of the people who fell ill had spent some time in Yosemite Valley, where park offices, visitor services, snack shops, hotels and restaurants are clustered. Park authorities haven't tested food or facilities for traces of norovirus, but Gediman said that they and concession operators have been working to clean and disinfect public buildings, including the famous Ahwahnee hotel.

The hotel's operator, Aramark Corporation, didn't respond to specific questions about the reports of illness but said in a statement that it shared the Park Service’s "confidence that all parties are taking the necessary steps to address the situation."

Aramark, which has managed Yosemite’s concessions since 2016, has been criticized for poor food quality and other problems, the San Francisco Chronicle reported.

In 2012, an outbreak of the hantavirus, which is spread through mouse droppings, killed three people who stayed at the park's Curry Village tent cabins.

The Associated Press contributed to this report.