Vomiting virus is spreading across most of the U.S.

Health newsVomiting virus is spreading across most of the U.S.Hikers along the Pacific Crest Trail in Southern California have been hit with norovirus, but they’re not the only ones suffering. Wastewater data shows high levels in many states.Listen to this article with a free account00:0000:00Southbound hikers walk toward Pinchot Pass on the Pacific Crest Trail in California.David Madison / Getty Images fileShareAdd NBC News to GoogleMay 29, 2026, 5:00 AM EDTBy Shiv Sudhakar, M.D.Flu season may be mostly behind us, but a nasty, highly contagious stomach bug is rising.Subscribe to read this story ad-free Get unlimited access to ad-free articles and exclusive content.In recent weeks, hikers in Southern California have been hit with norovirus, according to the Pacific Crest Trail Association.Outdoor enthusiasts along the iconic trail aren’t the only ones suffering.Recent wastewater surveillance reveals an upward trend to “high” levels of norovirus across much of the country, with rates currently rising in the Northeast.From Aug. 1 to May 7, the Centers for Disease Control and Prevention’s NoroSTAT program recorded 1,194 outbreaks, compared with 2,534 during the same period the previous year — consistent with past averages.“At the national level, norovirus is still in the HIGH category due to high concentrations over the last 21 days,” Amanda Bidwell, the scientific program manager at WastewaterSCAN, an academic program through Stanford University in partnership with Emory University, said in an email.Norovirus is often called the “winter vomiting disease,” but it’s not unusual for outbreaks to continue through late spring, Bidwell said.The wastewater numbers also highlight an outbreak of norovirus in the San Francisco Bay Area, although the numbers nationwide are average for this time of year, said Dr. Linda Yancey, an infectious disease specialist at Memorial Hermann in the Houston area.“There really isn’t anything unusual about this one in California,” Yancey added....