The National Park Service (NPS) has initiated an investigation into an illness affecting rafters who participated in trips to the Grand Canyon in recent weeks. Reports from several individuals on social media indicate a cluster of unexplained illnesses that emerged after their return from two-week rafting trips starting in mid-May. Symptoms reported include fever, chills, fatigue, and pneumonia, with some individuals experiencing severe complications such as fluid in the lungs and loss of consciousness.
A Facebook group, Grand Canyon Private Boaters, noted that four people fell ill after a group of 16 completed a rafting trip in mid-June. User Steven King described various symptoms and mentioned that one individual was hospitalized after losing consciousness. Another person developed a condition described as "cobblestoning" on a bruised area of the shin.
Concerns have arisen regarding the potential causes of the illnesses, with speculation online suggesting mosquito-borne diseases like dengue fever and chikungunya. An infectious disease epidemiologist indicated that the symptoms and reports of mosquito bites might align with these viruses, although they are uncommon in the U.S. The expert noted that Arizona has mosquitoes capable of transmitting these viruses, and if someone exposed to them traveled to the canyon, they could have infected local mosquito populations.
The NPS and the Arizona Department of Health Services have not yet provided comments regarding the investigation.