At least 222 people at the Grand Canyon got sick with ‘explosive’ gastroenteritis, CDC says

GRAND CANYON, AZ (3TV/CBS 5) -- The Centers for Disease Control and Prevention released more details about a possible norovirus outbreak affecting Grand Canyon National Park visitors earlier this year.

Arizona’s Family reported that it hit dozens of river rafters, and backcountry campers had reported “explosive” gastrointestinal illnesses after a rafting group reported the first case on April 6. The CDC said 11 out of 28 rafters got sick on that trip. Initially, many who got sick reported having norovirus-like symptoms, with some samples testing positive for the virus.

However, as weeks passed, more reports came in as hiking groups, and summer vacationers visited the park. As a result, the CDC launched an investigation with researchers arriving at the park by the end of May. Three months later, the CDC released its findings, which indicate that the outbreak could have come from multiple sources.

According to CDC researchers, five people reported becoming ill before their trips, indicating a “potential for multisource introduction” of norovirus into the park. In addition, investigations into portable toilets from rafting trips revealed that while they each tested positive for norovirus, they had two distinct genotypes -- different genetic materials, meaning they came from other places. Park officials reported the last case of gastroenteritis on June 17. In all, researchers looked into the possibility of 222 people, more than 80% of them being visitors, who got sick in those three months. “We haven’t seen something like this kind of outbreak in about ten years,” Jan Balsom, a spokesperson for the park, told blog site The Daily Beast in June.

“For us to experience the several trips that did have norovirus, that was just unprecedented. We’ve never experienced anything to that level ever,” said John Dillon, the executive director of the Grand Canyon River Outfitters Association, made up of the 16 commercial rafting companies that take visitors on trips in the canyon.

Norovirus has similar symptoms to food poisoning. “Lots of nausea, vomiting, explosive diarrhea usually within 12-24 hours,” said emergency medicine doctor Frank LoVecchio.

LoVecchio said not only is the virus highly contagious, but you don’t need much of it to become infected. “It can live for a long time in a bathroom, it can stay dormant for a while,” he said.

That may have been the primary problem. According to the report, a portable toilet tested positive for norovirus. It’s a toilet multiple river rafting trips use; then the virus was taken into the river water. Dillon said that makes sense because every river trip launches from the same area.

“So, we would launch four commercial trips a day from Lee’s Ferry all summer long,” Dillon said. “We don’t want to expose the camp behind us to this outbreak either and that’s exactly what probably happened.”

If you visit the Grand Canyon, it’s important to know certain things you’d think could kill norovirus can’t. “Hand sanitizer, because those are alcohol-based, those won’t work. And filters. When you think of a Brita filter, common one, other things we used to filter water when we’re at the Grand Canyon, those won’t work,” LoVecchio said.

The report said many river outfitters were unaware that alcohol-based hand sanitizer doesn’t work. “That is news to us, but that’s not our practice. We don’t use alcohol sanitizer for hand wash; we use bleach,” said Dillon. “Certainly we learned from this experience the best we can.” Dillon said while this is an unprecedented outbreak, it’s still a relatively low number of people considering they have 700 trips a year and see about 24,000 rafters.

The CDC warns that as norovirus cases increase nationwide, the virus could resurge at the park as visitation levels return to near pre-pandemic levels. Therefore, travelers should practice extra hygiene and ensure they use and consume clean water. For example, drinking from spigots or park-provided fountains is safer than using most water bottle filters.

The CDC is still looking at all their survey responses to see if there was any overlap of food and drinks, river stop locations, other toilets, and any other factors that could have spread it.

What is norovirus?

Norovirus is a contagious virus that spreads through touching contaminated surfaces or food and drink. You can also get norovirus from someone already infected by the virus. Health experts say you’ll often start feeling sick within 12 to 48 hours. According to the CDC and the National Park Service, the virus can spread quickly on rafts or while camping. Symptoms include sudden vomiting and severe diarrhea lasting anywhere from one to three days. Fever, headache, body aches, dehydration, and chills are other commonly reported symptoms.

What can kill norovirus? Bleach, chlorine, and boiling the water.

MORE: You can read the full CDC report below

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