Popular US Hiking Trail Reports Norovirus Outbreak

The Pacific Crest Trail is 2653 miles long and runs from the Mexico-US border to the Canada-US border. States on the trail are Washington, Oregon, and California and the trail passes through 25 national forests and 7 national parks.

In 2022, there were multiple cases of acute gastroenteritis (AGE) reported along the Washington state portion of the Pacific Crest Trail. This was disclosed in a recent CDC Morbidity and Mortality Weekly Report.

The Washington State Department of Health initially received reports that Pacific Crest Trail hikers were falling sick with AGE. An investigation subsequently found 27 hikers became ill. Additional reports showed it was happening throughout the hiking season of 2022.

The MMWR reported a REDCap survey was posted on a Facebook group page for Washington Pacific Crest Trail hikers and displayed (with a quick response code) at trailhead locations where illness had been reported. The responses of the survey from 27 ill Pacific Crest Trail hikers provided symptoms, locations, and contact details. Of them, 22 hikers reported onset dates. Two hikers did test positive for norovirus by real-time reverse transcription–polymerase chain reaction (RT-PCR).

“Twenty (74%) survey respondents reported an illness of short duration (median = 2.5 days; 95% CI = 1–15.7 days); among 22 (81%) who reported signs and symptoms, those most commonly reported were fatigue (21; 95%) and vomiting and diarrhea (17; 77%),” the investigators wrote.

Ninety-five percent of the survey respondents said they became ill along a 73 mile stretch of the trail in Washington, which investigators say suggested an environmental exposure.

Subsequently, investigators gathered samples from drinking water sources and a cabin and latrines within the area they identified as the likely exposure area.

“Despite absence of detection of norovirus from environmental sampling, symptom profiles, respondent and environmental laboratory results, and epidemiologic links all supported the conclusion that the outbreak was primarily caused by norovirus, and that exposure to contaminated surfaces within the cabin and VIP latrines likely amplified transmission,” the investigators wrote in the report.

Symptoms and Prevention

Symptoms for norovirus include vomiting, diarrhea, and stomach cramps. There is no treatment for the virus, and it typically lasts 1-2 days.

Norovirus is extremely contagious, and prevention is key. The MMWR noted hikers like to use alcohol-based sanitizers and these products do not protect against norovirus. Hand-washing using soap is recommended by CDC, and if hikers are not near a public bathroom, they should use clean water and wash their hands with a bar of soap for 20 seconds, and at least 200 feet from a water source.

In addition, the Pacific Crest Trail Association asks hikers to protect water quality by not washing dishes or their bodies in water sources.