Illness on Colorado River

Grand Canyon, AZ
June 13, 2002

A gastrointestinal illness has once again swept the Colorado River in Grand Canyon. Two commercial river trips that finished their trip within the last three days reported having 17 passengers experience vomiting and diarrhea for 24 to 48 hours. One more commercial river trip and one non-commercial river trip also had a large group of ill passengers, and were scheduled to take off the river today. The attack rate of illness on these two trips is estimated to be 50%.

"This is a Norwalk type virus, similar to the outbreaks noted in 1994 and 2000" noted Grand Canyon National Park Public Health Officer Jim Nothnagel. The Norwalk virus is a gastrointestinal disease that only effects humans, and is highly contagious. According to Nothnagel, of the 38 cases of illness reported on the river last year, most were brought on to the river and were probably the flu that was going around Flagstaff last summer.

The key to avoiding getting sick while floating through Grand Canyon is proper water treatment, according to Nothnagel. Drinking water should be filtered through a one micron or less filter, and then chlorinated with 2 drops per gallon of chlorine or Iodine. This treated water will then be available for drinking in 30 minutes.