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Grand Canyon visitors infected with highly contagious norovirus

More than 150 campers and rafters reported nausea, stomach cramping, vomiting and diarrhea

The Black Bridge at the bottom of the Grand Canyon. (PeteHendleyPhotography/iStock)

More than 150 rafters and backcountry campers who visited the Grand Canyon in April and May reported symptoms of a gastrointestinal illness, the National Park Service said this week.

The symptoms — including nausea, stomach cramping and pain, vomiting, and diarrhea — are representative of norovirus, according to a release from the National Park Service Office of Public Health. Officials confirmed the virus was found on at least eight of the rafting trips in the national park so far.

Park officials said “comprehensive control measures” have been implemented in response, and since early June they’ve seen a “a marked decrease in reports of illness.”

This volume of cases is rare, said John Dillon, executive director for the Grand Canyon River Outfitters Association (GCROA), which represents rafting companies authorized to guide trips in the park.

“This is the cruise ship virus, right?” Dillon said. “So it’s very unusual for us to experience something like this in the backcountry.”

In a typical season, the companies run about 650 trips; Dillon said having one or two of them report a norovirus case could be considered normal.

The exact cause hasn’t been identified, but Dillon said GCROA is working with officials, including the CDC, to gather data on the outbreaks.

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Sometimes (incorrectly) referred to as “the stomach flu,” norovirus is a highly contagious illness that causes the stomach and intestines to become inflamed. Symptoms can appear 12 to 48 hours after being exposed and can cause reoccurring vomiting or diarrhea throughout the day, which can lead to dehydration. In most cases, it passes in one to three days.

The virus is transmitted through contaminated food or drinks; putting your hands in your mouth after touching a contaminated surface; or having direct contact with someone infected by it (such as sharing drinks or utensils with them).

“On rafts and in camps, norovirus can spread quickly,” NPS said. “The best way to prevent norovirus is to practice proper hand washing and general cleanliness and ensure the safety of your drinking water.”

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Grand Canyon visitors can safely consume water from park-provided fountains and spigots.

Park officials said it is not safe to drink water from natural sources, such as the Colorado River, side streams, waterfalls or pools — although it may have once been in the past. Any collected water should be filtered and chemically disinfected, or be boiled with a rolling boil for at least a minute in most cases (at least three minutes for elevations 6,500 feet and above).

If a traveler gets sick, Dillon said, that person should be separated from the rest of the group to prevent any spread, and then guides would follow sanitization protocols. In extreme cases, guides could use satellite phones to call in a helicopter to evacuate the traveler to a hospital.

To avoid disaster and illness, Dillon said, it is critical to use good judgment during your adventure, respect the conditions and the location, and listen to guides.

“A Grand Canyon trip in general — whether it’s to the rim or to the river — needs to be a highlight of one’s life ... not the misery of being ill or injured,” he said.