August 1, 2002
For Immediate Release
CONTACT: Maureen Oltrogge 928-638-7779
National Park Service Investigating Outbreak of Gastrointestinal Illness on the Colorado River
Grand Canyon, AZ – The National Park Service is currently investigatingnine cases of gastrointestinal illness reported on the Colorado River earlythis morning. The illnesses were reported by a river guide on a commercialtrip camped at Hells Hollow at River Mile 183 near Whitmore Wash. Two ofthe nine individuals, a 47 year old male and a 16 year old male, weretransported to the Grand Canyon Clinic on the South Rim of Grand CanyonNational Park where they were treated and released. The remaining sevenpassengers who reported symptoms planned to complete the last two days oftheir eight-day trip.
Between June 1 and 14 of this year, 59 persons participating in fiveseparate rafting trips on the Colorado River through Grand Canyon NationalPark developed gastrointestinal illness. Passengers reported flu-likesymptoms consisting of nausea, vomiting, and diarrhea. The symptomsreported this morning are similar. Evidence from stool specimens takenfrom those affected by the illness in June indicated that a Norwalk-likevirus had caused the outbreak. The Centers for Disease Control andPrevention is working to confirm the illness by genetic sequencing, andshould have the results later this summer. Results from initialenvironmental tests taken in June and an epidemiology study comparingindividuals who became sick with individuals who remained healthy are alsopending.
The National Park Service continues to work with the United States PublicHealth Service, Coconino County Department of Health Service, Arizona StateEpidemiology Office, and the Centers for Disease Control and Prevention todetermine a cause and source of the illness. Specimens collected fromindividuals in this latest group who became ill will be analyzed andcompared to results from those tested in June to help determine if thereare any common point sources of the virus.
River and backcountry users are reminded to be extra vigilant with theirsanitation practices. Drinking water obtained from the Colorado River orside canyons should be filtered and treated with iodine or chlorine, thenallowed to rest before consumption. An alternative method is to boil alldrinking water. Frequent hand washing and careful food preparation helpsto control the spread of the illness from person to person. River guideswho develop the illness while on a trip should not participate in foodpreparation.