Cluster of mystery illnesses among Grand Canyon rafters prompts investigationMultiple people who paddled the Colorado River have described symptoms including fever, chills, fatigue and fluid in their lungs.Matt Wappett, along with his wife and daughter, got sick after paddling the Grand Canyon.Courtesy Matt WappettJuly 8, 2026, 8:17 PM EDTMystery illnesses have struck several groups of Grand Canyon rafters who paddled the Colorado River, prompting the National Park Service to investigate whether something in or along the river is making people sick.Just a moment.We are getting your experience ready.