Genetic Analysis of Norovirus Strains that Caused Gastroenteritis Outbreaks Among River Rafters in the Grand Canyon, Arizona.

Toilet solid waste samples collected from five outbreaks among rafters in the Grand Canyon were subjected to sequencing analysis of norovirus partial capsid gene. The results revealed that a GI.3 strain was associated with one outbreak, whereas the other outbreaks were caused by GII.

Norovirus Outbreaks Among Colorado River Rafters in the Grand Canyon, Summer 2012.

Objective: To investigate the incidence and causative agent of the recurrent outbreaks of acute gastrointestinal illness (AGI) among different rafting groups on the Colorado River in the Grand Canyon National Park during the 2012 summer season.

Methods: Confidential illness reports were completed by all individuals with symptoms of AGI, and samples of fecal matter and vomitus, surface swabs of rafting equipment, and environmental swabs at stops along the hiking corridor were collected and tested for the presence of norovirus using reverse transcription-quantitative polymerase chain reaction (RT-qPCR).

Results: During the active outbreak period between May 9 and July 9, 2012, 97 rafters (1.