Flu-Like Outbreak Studied

Health officials at the Grand Canyon say they’re figuring out ways to prevent outbreaks of a flu-like virus that affected dozens of hikers and rafters this summer.

A report released this week reveals that water from a sewage treatment plant at Glen Canyon Dam has tested positive for the Norwalk disease. The virus was also found downstream in the Lees Ferry area.

National Park Service scientists say they will test further to determine whether there are other sources of the virus along the Colorado River.

Chuck Higgins, a regional public health specialist with the park service, says researchers are certain the virus is spreading through river water. “It’s very important because the main angles we try to use to prevent any illness are the cycles of the illness, and once we know that, we can break the cycles,” he said.

Health officials advise river runners to take extra precautions to purify water. The Bureau of Reclamation is examining how the Glen Canyon plant treats wastewater before it’s discharged into the Colorado.

Since May, more than 130 Grand Canyon hikers and rafters have come down with the disease, which causes vomiting and diarrhea and lasts a day or two.

Still, a Grand Canyon rafting spokesman said the outbreaks have never posed a threat to the local industry, which serves thousands of customers each summer. “It’s not fun to be sick, but in terms of the industry, it wasn’t that widespread,” said Mark Grisham, executive director of the Grand Canyon River Outfitters Assn. The local river-running season usually runs from April until mid-October.

Members of the industry will soon learn more about disease prevention. Higgins is set to address about 200 guides at the annual meeting of the Grand Canyon River Guides association this weekend in Flagstaff.

The close person-to-person contact of rafting trips makes it easy for the disease to spread. Water-filtration and food-handling methods can be tightened to reduce the spread of germs, Higgins said.

Higgins also discussed his findings with the Bureau of Reclamation, which operates Glen Canyon Dam. Bureau spokesman Barry Wirth says the agency wants to see more data on possible virus sources before making any major changes.

“Our commitment is to participate with the park service and everyone else involved to do the study work and take a look at how we may alter our practices in the plant to reduce ... Norwalk,” Wirth said. “Right now, our plant meets all the standards for sewage plants, but what we are hearing is that Norwalk may take more.”

Wirth said the plant at the northeastern end of the canyon uses ultraviolet light to treat sewage. The facility handles a relatively small amount of wastewater, mostly from bathrooms on the dam and its power plant, Wirth said.

Higgins said further research may reveal that Norwalk requires treatment more advanced than what is called for by current standards. And that could have national implications.

“It could be surviving standard sewage-treatment processes,” Higgins said. “If so, that would have larger implications that the [Centers for Disease Control and Prevention] and [the Environmental Protection Agency] would have interest in.”