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Mystery Stomach Virus Strikes 59 Colorado River Rafters

The Arizona Republic | June 20, 2002
by Judd Slivka, The Arizona Republic

They were the trips of lifetimes, days spent plowing through rapids and nights camping beneath the Grand Canyon's walls. Right up until people started getting sick.

In the first two weeks of June, 59 river rafters in the Grand Canyon came down with some kind of illness that had them sick to their stomachs for a day or two.

Officials with the National Park Service and the Centers for Disease Control and Prevention are trying to figure out what is happening on the Colorado River.

The virus is probably a member of the Norwalk family of viruses, said Chuck Higgins, the Park Service's regional medical services director. Included in that group of viruses are several that typically look like stomach flu.

The virus first showed up June 1 at River Mile 164, just above the Hualapai Reservation. By June 14, it was showing up far downriver at National Canyon near Lake Mead. There's no pattern: Cases have surfaced on four outfitters' trips and one private boat trip.

"We don't know if it was from people drinking river water, not chlorinating it enough, standing under a waterfall with their mouths open," Higgins said.

The outbreak is similar to, although more severe than, viral episodes on the river in 1994 and 2001 that resulted in new reporting procedures for illnesses on the river.

Six people from the state and the Park Service are working on the case, and the CDC is trying to determine how people contracted the virus. Airborne transmission seems to be one possibility.

"There's a pattern that suggests that one person in a group will get sick, and then several others in the groups would get sick," Higgins said.

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