Overview
- People who rafted the Colorado River through the Grand Canyon in mid‑May to early June have reported falling ill days to weeks after returning, with symptoms that include fever, fatigue, joint pain, pneumonia and localized skin infections.
- Rafters shared accounts in a private Facebook group describing clusters of cases on the same trips, including one report that four of 16 people on a June trip became sick.
- The National Park Service confirmed an active inquiry led by its Office of Public Health and said it is coordinating interviews with public‑health partners and affected individuals.
- Clinicians have treated some patients for conditions such as cellulitis and pneumonia while lab testing for possible causes such as valley fever, dengue and hantavirus remains pending.
- Investigators note multiple plausible exposure routes—outdoor sleeping, insect bites, river water and soil contact—and cautioned that social‑media clustering can signal either a real outbreak or unrelated illnesses, so formal case definitions and lab confirmation are needed.