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The U.S. National Park Service is investigating reports of a mysterious illness that has affected several people after rafting trips along the Colorado River through Grand Canyon National Park. While the exact cause remains unknown, federal officials are working with public health experts to determine whether the reported cases are connected.
The investigation follows multiple accounts from rafters who developed severe flu-like symptoms and other health complications after returning home from their river expeditions. The reports have raised concerns among outdoor enthusiasts, river guides, and future visitors planning rafting adventures in one of America's most popular national parks.
According to the National Park Service (NPS), officials have received reports from individuals who experienced a variety of symptoms after completing rafting trips through the Grand Canyon on the Colorado River.
The reported symptoms include:
The agency confirmed that its Office of Health and Safety is coordinating with public health authorities to review the reported illnesses and identify any possible causes.
At this stage, officials have not announced how many people have been affected or whether all cases are linked to the same medical condition. They have also not identified a specific source of the illness.
One of the individuals who publicly discussed his illness is Utah resident Matthew Wappett. After completing a rafting trip in mid May, he said he became seriously ill only a few days after returning home.
According to his account, he visited an emergency room after developing an infected knee accompanied by severe joint pain. Doctors later diagnosed him with cellulitis, a bacterial skin infection that can become serious if left untreated.
Although antibiotics helped treat the knee infection, Wappett said his health continued to decline. He later experienced symptoms similar to pneumonia and influenza that lasted for more than a month.
In a social media post, he described the illness as physically and mentally exhausting and said he had never experienced anything similar before.
He also recalled receiving several mosquito bites during the rafting trip, although it remains unclear whether insect bites played any role in his illness.
After sharing his experience in a Facebook group dedicated to Grand Canyon rafters, Wappett discovered that several other people had reported comparable symptoms following separate rafting trips.
Another rafter, Steven King, also shared details about illnesses affecting members of his travel group.
According to King, four people from a group of sixteen developed symptoms that included fever, weakness, chills, and fluid buildup in the lungs. Medical professionals reportedly conducted extensive blood testing but had not reached a definitive diagnosis.
King said one traveler was initially believed to have pneumonia, while another received a diagnosis of cellulitis.
Like Wappett, King also remembered seeing mosquitoes during portions of the river journey.
Although these personal accounts suggest similarities between cases, health officials have not confirmed that they are connected or caused by the same illness.
Both Wappett and King completed rafting trips covering the stretch of the Colorado River between Lees Ferry and Diamond Creek.
This approximately 225 mile route is one of the most popular sections for rafting and kayaking through Grand Canyon National Park. Thousands of visitors travel this section every year to experience the canyon's unique landscapes, whitewater rapids, and remote wilderness.
Because multiple reported illnesses involve travelers who completed similar routes, investigators may examine whether environmental conditions, water exposure, insects, bacteria, or other factors contributed to the reported health problems.
However, officials have not identified any environmental hazard or confirmed any specific source at this time.
Several reported cases involved cellulitis, a bacterial infection affecting the deeper layers of the skin and surrounding tissue.
Common symptoms of cellulitis include:
The condition usually develops when bacteria enter the body through cuts, scrapes, insect bites, or other breaks in the skin. Early treatment with antibiotics is generally effective, although severe infections may require hospitalization.
It is important to note that not every reported illness involved cellulitis, and investigators have not determined whether cellulitis is connected to the broader reports being reviewed.
Several potential explanations could account for the reported illnesses, but none have been confirmed.
Public health experts may consider a range of possibilities, including bacterial infections, viral illnesses, insect borne diseases, environmental exposures, or unrelated medical conditions occurring around the same time.
Until laboratory testing and epidemiological investigations are completed, it would be premature to conclude that all reported cases share the same cause.
Officials have not advised visitors to avoid rafting in Grand Canyon National Park, and there have been no announcements regarding park closures or restrictions related to the investigation.
While the investigation continues, visitors planning rafting or camping trips can reduce health risks by following general outdoor safety practices.
These include:
Anyone experiencing persistent symptoms following a rafting trip should contact a healthcare provider and inform them about recent travel and outdoor exposure.
The National Park Service continues working alongside public health agencies to better understand the reported illnesses affecting some Grand Canyon rafters.
As investigators collect additional information, they hope to determine whether the cases share a common source or represent unrelated medical events.
For now, officials emphasize that the investigation is ongoing and that no confirmed cause has been identified.
Visitors planning future rafting trips should stay informed through official National Park Service updates while following recommended outdoor safety precautions.
This article is intended for informational purposes only and should not be considered medical advice. The reported illnesses remain under investigation, and no official cause has been confirmed by health authorities. Anyone experiencing concerning symptoms should seek evaluation from a qualified healthcare professional.
NTD Television, July 8, 2026.