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Vomiting Bug Spreads Rapidly Across US
29 May
Summary
- Norovirus outbreaks are widespread across the U.S., affecting Southern California hikers.
- Wastewater surveillance indicates high nationwide levels of norovirus, especially in the Northeast.
- Symptoms appear 12-48 hours after exposure and can cause severe dehydration in vulnerable groups.
A highly contagious norovirus is currently spreading through most areas of the U.S. Recent reports indicate illness among hikers in Southern California. Wastewater surveillance data from August 1, 2025, to May 7, 2026, shows 1,194 norovirus outbreaks were reported by participating states.
Nationwide, norovirus levels are in the "HIGH" category, with the Northeast and Midwest seeing elevated concentrations. While typically a winter illness, elevated levels are expected through late spring. Monitoring wastewater is crucial as many recover at home without seeking medical attention.
Symptoms of norovirus, which include nausea, vomiting, and stomach pain, usually appear 12 to 48 hours after exposure and can last one to three days. Although most individuals recover without treatment, older adults, young children, and those with existing health conditions are at risk of severe dehydration and may require medical care.
