Norovirus Is Hitting A Popular CA Attraction Hard As Cases Rise Across U.S.

A norovirus outbreak has struck a popular California hiking trail, but nobody knows where it's coming from.

Dozens of hikers have reportedly experienced gastrointestinal problems while traveling along the Pacific Crest Trail near the mountain village of Wrightwood, 77 miles northeast of Los Angeles, according to a report from Discover Magazine.

In at least one case, one person was airlifted from the trail after becoming severely ill, according to SFGate, which said they were later diagnosed with norovirus.

It's unclear where the source of the virus may be coming from. Norovirus, the highly contagious stomach bug, is most commonly associated with the winter holiday season.

Health officials confirm spiking norovirus activity in California, contributing to a rise in seasonal stomach bugs. In late January, the virus spiked dramatically in the Bay Area and the Los Angeles area, analysis of wastewater at 57 surveillance sites shows.

Several treatment plants across California, including in Lompoc, Redwood City and Sacramento, are still detecting a high concentration of norovirus as of May, according to data from WastewaterSCAN.

Eleven more sites have reported a medium concentration of the virus, including multiple sites in San Francisco.

"Norovirus is like the cockroach of viruses," Noelle Harrison, a retired public health educator and hiker in Dunsmuir, told SFGATE. "It’s almost impossible to kill, and if you end up getting sick in really remote areas, some of its more severe symptoms can put you in a really bad place."

Norovirus concentration levels are also high across the country, according to recent wastewater tests.

From Aug. 1, 2025, to May 7, there were 1,194 norovirus outbreaks, according to the Centers for Disease Control and Prevention.

Despite the high levels, the number of outbreaks is still significantly less than the same period in 2025, when there were 2,534 norovirus outbreaks.

There are about 2,500 reported norovirus outbreaks a year, according to the CDC. Some health experts worry that the variant GII.17, which was responsible for last year's spike, may have mutated and become more contagious.

Symptoms of the GII.17 strain include forceful vomiting, intense diarrhea and stomach cramps that are especially hard on children under 5, adults over 85, and those with underlying health conditions, according to the CDC. Dehydration is a primary risk.

Because GII.17 is a new strain, people have less built-up immunity and may experience more severe illnesses.

"Historically, new strains emerge every seven to 10 years, and we were due for one, so this is not surprising," Lee-Ann Jaykus, a professor in the Department of Food, Bioprocessing and Nutrition Sciences at North Carolina State University, told Newsweek.

Health officials advise people to wash their hands well with soap and water. Hand sanitizer alone does not work well against norovirus. Also, do not prepare, handle food, or care for others when you are sick.

The Pacific Crest Trail spans 2,650 miles from Mexico to Canada, passing through California, Oregon and Washington.

Local editor Kristina Houck contributed to this report.