At least two people have been diagnosed with confirmed cases of norovirus at Yosemite National Park as of Thursday and about 170 have gotten sick with characteristic gastrointestinal symptoms, according to the National Park Service.

The people who have gotten sick include both visitors to the park and employees who spent time there. Most of those cases occurred around the first week of the month, according to the NPS, and new cases have apparently been declining over the last several days.

Yosemite National Park
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Yosemite National Park officials and medical professionals with the National Park Service Office of Public Health (OPH) are continuing to investigate the circumstances surrounding the illness and are continuing to conduct interviews with affected people,” the NPS said in a statement. “The overwhelming majority of the reported cases are consistent with norovirus.”

According to the NPS, the “park continues to undertake extensive cleaning and enhanced sanitation protocols.”

The highly contagious norovirus disease is spread from having contact with an infected person or eating or drinking contaminated food or water, according to the Centers for Disease Control and Prevention. Common symptoms include diarrhea, vomiting, nausea, and stomach pain.

Symptoms of norovirus typically present from 12 to 48 hours after a person is exposed to the disease and usually resolve within one to three days, the CDC noted. If you are sick with the disease, it is imperative to drink plenty of liquids to prevent dehydration.

While norovirus outbreaks can occur any time of the year, they are most common from November through April. The disease is also the most common cause of vomiting, diarrhea and foodborne illness.

The agency is warning visitors to wash their hands frequently with soap and water, avoid sharing food and drinks, and update a healthcare provider if they feel sick. Additionally, the NPS has asked people who do come down with these stomach symptoms in Yosemite National Park to email them to report it.