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.
It causes inflammation of the stomach and intestines, causing stomach pain, nausea and diarrhea.
The Ahwahnee Hotel in Yosemite National Park, California where two peole reported feeling ill after visiting earlier this month.
Two of those cases have been confirmed as norovirus, park officials say.More news: Virat Kohli Wins Spirit of Cricket Honour at ICC Awards
So far about 170 people who have visited or work at the park have reported having stomach issues, diarrhea and vomiting.
Norovirus can spread quickly, including through direct contact with an infected person, by touching a contaminated surface or object, or by eating food or drinking liquids contaminated with the virus.
The origin of the outbreak is not yet clear and park officials said it would be hard to trace where it came from.
Reconnecting with nature is always a good time, but almost 200 visitors to California's Yosemite National Park may have gotten a little more than they bargained for.More news: Tussauds removes waxworks of Harry, Meghan from royal family display
The spokesman said the park was undertaking "extensive cleaning and enhanced sanitation protocols" to address the outbreak.
Last year, complaints and bad reviews stacked up from visitors who were unhappy with food and the long waits for shuttle services.
The Ahwahnee Hotel, which costs about $1,000 a night, lost its prestigious four-diamond rating by AAA, a distinction the luxury hotel held since 1991. "We've had very few new cases reported lately, so we're hopeful that we're on the downward cycle of it".
"It's highly contagious, so if an infected person touches a banister and someone else touches it, they can get it", Scott Gediman, a Yosemite park spokesperson told the San Francisco Chronicle.More news: Panama: 7 killed in weird religious ritual