Grand Canyon, AZ
August 3, 2002
The National Park Service is currently investigating nine cases of gastrointestinal illness reported on the Colorado River August 1, 2002. The illnesses occurred on a two boat commercial trip camped at Hells Hollow at River Mile 183 near Whitmore Wash. All of the nine cases were from one of the boats. Two of the nine individuals, a 47 year old male and a 16 year old male, were transported to the Grand Canyon Clinic on the South Rim of Grand Canyon National Park where they were treated and released. The remaining seven passengers who reported symptoms planned to complete the last two days of their eight-day trip.
Between June 1 and 14 of this year, 59 persons participating in five separate rafting trips on the Colorado River through Grand Canyon National Park developed gastrointestinal illness. Passengers reported flu-like symptoms consisting of nausea, vomiting, and diarrhea. The symptoms reported in this latest outbreak are similar to the June incident. Evidence from stool specimens taken from those affected by the illness in June indicated that a Norwalk-like virus had caused the outbreak. The Centers for Disease Control and Prevention is working to confirm the illness by genetic sequencing, and should have the results later this summer. Results from initial environmental tests taken in June and an epidemiology study comparing individuals who became sick with individuals who remained healthy are also pending.
River and backcountry users are reminded to be extra vigilant with their sanitation practices. Drinking water obtained from the Colorado River or side canyons should be filtered and treated with iodine or chlorine, then allowed to rest before consumption. An alternative method is to boil all drinking water. Frequent hand washing and careful food preparation helps to control the spread of the illness from person to person. Any river runner who develops the illness while on a trip should not participate in food preparation.