Mysterious Illness Investigation in the Grand Canyon

The National Park Service (NPS) has begun looking into a strange illness that seems to be affecting rafters who visited the Grand Canyon recently.

Last week, some individuals took to social media, raising concerns about an unknown ailment that has doctors baffled. A rafter, along with others, reported that symptoms intensified after they returned from a two-week trip starting in mid-May.

Paddling Magazine noted that park authorities are currently investigating reports of severe symptoms among rafters.

Online discussions regarding the potential causes of this illness have emerged. Some medical professionals suggest it might be linked to mosquito-borne diseases such as dengue or chikungunya.

According to a Facebook group, Four people from a group of 16 came down with similar symptoms after embarking on a rafting journey in mid-June.

In a post on July 1, Stephen King shared that members of the group exhibited various symptoms, including fever, chills, fatigue, and even pneumonia. He noted that some experienced more severe issues, like fluid in their lungs and a loss of consciousness.

“One individual passed out briefly during an exam and had to be hospitalized,” King reported.

He also mentioned another group member who developed a painful condition known as “cobblestone,” resembling cellulitis in the bruised area of the shins, which felt like a broken bone.

“X-rays showed no damage, and oddly, it seems to be deteriorating instead of healing,” he added.

Extra precautions are being taken for affected individuals since the source of this suspected illness remains undetermined.

“One person started rabies vaccinations just to be safe, despite not showing any actual symptoms,” said a group member.

King stated that they didn’t encounter ticks but did notice mosquitoes at night during their canyon stay.

In a separate incident, Matthew Wappett shared his experience after a two-week trip in mid-May, mentioning swollen knees and “bone-crushing” joint pain, along with mosquito bites during the outing.

“We were outside every night and certainly dealt with mosquitoes,” Wappett wrote in a post on July 2.

An infectious disease epidemiologist suggested that these illnesses might relate to mosquito-borne viruses like dengue or chikungunya.

“Given the symptoms and reports of mosquito bites—with no gastrointestinal issues or tick encounters—it likely appears viral. The symptoms align well with both dengue and chikungunya,” the expert stated.

Squire noted that, although dengue and chikungunya are uncommon in the U.S. compared to other regions, Arizona does have mosquitoes capable of carrying both viruses.

“If individuals who were exposed to these viruses abroad entered the canyon, they could have inadvertently transmitted the virus to local mosquitoes,” Squire suggested.

Medical professionals also indicated that if patients do not mention recent international travel, identifying the cause could be more challenging, and testing for specific viruses might take longer.

“Those reporting these symptoms without any recent international travel are less likely to undergo testing for these viruses in Arizona,” Squire emphasized.

As of now, the NPS and the Arizona Department of Health Services have not provided comments regarding the situation.