While hiking in Grand Canyon National Park, Kristi Key came across a concerning site: four hikers resting on the side of the trail, looking a little worse for wear. After learning that two of the hikers had spent the previous night violently vomiting, Key offered to call a rescue team, but the group declined. But when she saw them sitting in the same spot on her return trip, with one of the hikers still vomiting, she knew it was time to call for help.
Eventually, a chopper showed up, flying the nausea-stricken man to safety. But the experience stuck with Key, who told The Daily Beast that she has hiked hundreds of miles in the Grand Canyon and never come across hikers whose illness was unrelated to dehydration or heat—until now. After a once-healthy member of the unlucky group fell ill later that day, Key began to suspect that a virus was to blame.