Dozens of hikers fell ill during visits to waterfalls near the Grand Canyon

Dozens of hikers say they have fallen ill during trips to a popular Arizona tourist destination that features towering blue-green waterfalls at the bottom of a nearby gorge in Grand Canyon National Park.

Madelyn Melchiors, a 32-year-old veterinarian from Kingman, Ariz., said she was vomiting severely Monday night and had a fever that persisted for days after camping on the Havasupai reservation.

She eventually made it back to her car in a weakened state from sweltering heat and was grateful that her bag could be carried down a winding trail for several miles on the back of a mule, she said.

“I said, 'If someone can just pack my 30-pound pack, I think I can just limp,'” said Melchiors, an experienced and regular backpacker. Then, “I slept for 16 hours and drank a lot of electrolytes. I'm still not normal, but I'll be okay. I am grateful for that.

The federal Indian Health Service said Thursday that a clinic it oversees on the reservation was providing timely medical care to people who became ill. Environmental health workers from the IHS regional office were sent to Havasupai to investigate the source of the outbreak and implement measures to prevent it from spreading, the agency said.

“Our priority is the health and well-being of Havasupai residents and visitors, and we are working closely with local health authorities and other partners to effectively manage this situation,” the agency said in a statement .

While camping, Melchiors said she drank from a spring tested and listed as safe to drink, as well as other sources that use a gravity-fed filter that removes bacteria and protozoa — but not viruses.

“I did a really good job of using hand sanitizer” after going to the bathroom, she said. “It’s not like you can use soap or water easily.”

Coconino County health officials said Tuesday they received a report of a group of people who had hiked to the waterfalls suffering from “gastrointestinal illnesses” but did not know how many people had been affected. The tribe's lands are outside of county jurisdiction.

Still, county health spokeswoman Trish Lees said hikers should take extra precautions to prevent the spread of disease, including filtering water.

“Watch for early symptoms of norovirus, such as stomach pain and nausea, before traveling. Norovirus spreads easily during camping trips, especially when supplies of drinking water may be limited and hand-washing facilities may be nonexistent. Isolate sick people from other campers,” the county said.

Thousands of tourists travel to the Havasupai Preserve each year to camp near a series of picturesque waterfalls. The reservation is isolated and accessible only by foot, helicopter, or by horse or mule.

The hike takes tourists 13 kilometers on a winding trail through a desert landscape before reaching the first waterfall. Next comes the village of Supai, where 600 members of the tribe live year-round. An additional 2 miles down the trail are campsites with waterfalls at both ends.

Tourism is the main source of income for the Havasupai tribe. The campground crossed by a stream has limited infrastructure. The hundreds of campers who stay overnight each day can use composting toilets on site and are asked to pick up their trash. Recent accounts from hikers on social media indicate that the trails are littered with trash, including toilet paper, plastic bottles and gasoline cans.

The Havasupai Tribe Tourism Office said it tested water from a local spring that visitors rely on for drinking last week and found it was safe for human consumption.

FOX-10 TV in Phoenix first reported on the illnesses Wednesday, saying some groups chose to exit the canyon by helicopter because they were too sick to get out.

Dozens of other people have posted on social media in recent days describing their gastrointestinal problems.

“I definitely have a literally bitter taste in my mouth right now,” Melchiors said. “I think I would approach things a little differently.”

___ Sonner reported from Reno, Nevada. Lee reported from Santa Fe, New Mexico.