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

Magill-Collins, Anne; Gaither, Marlene; Gerba, Charles P.; Kitajima, Masaaki; Iker, Brandon C.; Stoehr, James D.

doi:10.1016/j.wem.2015.02.007

Cited by 14 publications

(13 citation statements)

References 17 publications

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“…Despite the clear role of vomiting in transmission, there is very little data on viral loads in emesis. An investigation of norovirus outbreaks among rafters in the Grand Canyon detected GI norovirus in a vomitus sample [ 20 ]. In samples collected during a GI.1 Norwalk virus human challenge trial, 56% of emesis samples had detectable virus and the median titer was 4.1x10 4 gEq/ml [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Vomiting as a Symptom and Transmission Risk in Norovirus Illness: Evidence from Human Challenge Studies

2016

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BackgroundIn the US, noroviruses are estimated to cause 21 million cases annually with economic losses reaching $2 billion. Outbreak investigations frequently implicate vomiting as a major transmission risk. However, little is known about the characteristics of vomiting as a symptom or the amount of virus present in emesis.Methodology and Principal FindingsEmesis samples and symptomology data were obtained from previous norovirus human challenge studies with GI.1 Norwalk virus, GII.2 Snow Mountain virus, and a pilot study with GII.1 Hawaii virus. Viral titers in emesis were determined using strain-specific quantitative RT-PCR. In all four studies, vomiting was common with 40–100% of infected subjects vomiting at least once. However, only 45% of subjects with vomiting also had diarrhea. Most of the emesis samples had detectable virus and the mean viral titers were 8.0 x 105 and 3.9 x 104 genomic equivalent copies (GEC)/ml for GI and GII viruses, respectively (p = 0.02). Sample pH was correlated with GII.2 Snow Mountain virus detection.Conclusions and SignificanceHalf of all subjects with symptomatic infection experienced vomiting and the average subject shed 1.7 x 108 GEC in emesis. Unlike shedding through stool, vomiting is more likely to result in significant environmental contamination, leading to transmission through fomites and airborne droplets. This quantitative data will be critical for risk assessment studies to further understand norovirus transmission and develop effective control measures. The correlation between sample pH and virus detection is consistent with a single site of virus replication in the small intestine and stomach contents becoming contaminated by intestinal reflux. Additionally, the frequency of vomiting without concurrent diarrhea suggests that epidemiology studies that enroll subjects based on the presence of diarrhea may be significantly underestimating the true burden of norovirus disease.

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Section: Introductionmentioning

confidence: 99%

Vomiting as a Symptom and Transmission Risk in Norovirus Illness: Evidence from Human Challenge Studies

2016

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“…As reported in Magill-Collins et al 2015, screening of the presence of norovirus-RNA in the toilet solid waste samples using RT-qPCR demonstrated that one sample tested positive for GI and the other samples were positive for GII (no GI/GII coinfection was observed), while GIV was not detected from any samples (Magill-Collins et al 2015). This result is consistent with other clinical studies on norovirus, which reported that GII accounts for the large majority of reported outbreaks and GI makes up the majority of the remaining cases, whereas GIV strains have rarely been detected from patients.…”

Section: Textmentioning

confidence: 51%

“…Norovirus outbreaks among the Colorado River rafters in the Grand Canyon have been reported in the last few decades (Jones et al 2009;Malek et al 2009). In summer 2012, we experienced large recurrent gastroenteritis outbreaks among the Colorado River rafters and recently reported the results of our epidemiological investigation (Magill-Collins et al 2015).…”

Section: Textmentioning

confidence: 62%

“…In brief, we collected epidemiological information through confidential illness reports from ten trips (2.9% trip infection rate; out of 347 trips in total) that experienced gastroenteritis outbreaks in summer 2012. Fecal (composite solid waste from portable toilets) samples available from five out of the ten trips tested positive for norovirus-RNA, demonstrating that norovirus was probably the cause of gastroenteritis outbreaks (Magill-Collins et al 2015). In the present study, we performed follow-up analysis of the norovirus-positive samples to characterize and relate norovirus strains associated with the multiple outbreaks among river rafters in the Grand Canyon, summer 2012.…”

Section: Textmentioning

confidence: 89%

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

et al. 2017

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“…Rafters exposed to waters which drain large amounts of mountain streams are therefore at high risk of developing infection [18]. In addition there have been several norovirus outbreaks during whitewater rafting trips, presumably as travelers are close together, lack indoor plumbing and hand hygiene [19,20]. Travelers should be advised to bring soap for washing hands and ensure adequate water filtration if going on a rafting excursion.…”

Section: Whitewater Sportsmentioning

confidence: 99%

Infections associated with adventure travel: A systematic review

Gundacker

Rolfe

Rodríguez

2017

Travel Medicine and Infectious Disease

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a b s t r a c tAim: To review infections associated with adventure travel. Methods: The PubMed, Embase and Scopus databases were searched combining the words infection with the following keywords: rafting, whitewater, surfing, (surfer* or windsurf*), (caves or caving or spelunking), (triathlon or trekking) or (hiking or adventure race), bicycling, backpacking, (mountain climb* or bouldering), horseback riding, orienteering, trekking, and skiing. Results: Adventure travel is becoming much more common among travelers and it is associated with a subset of infectious diseases including: leptospirosis, schistosomiasis, viral hemorrhagic fevers, rickettsial diseases and endemic mycosis. Caving and whitewater rafting places individuals at particular risk of leptospirosis, schistosomiasis and endemic mycosis, while adventure races also place individuals at high risk of a variety of infections including campylobacter, norovirus and leptospirosis. Conclusion: Travel practitioners need to be aware of the risks associated with adventure travel and should educate individuals about the risks associated with various activities. Doxycycline prophylaxis should be considered for travelers who are susceptible to leptospirosis due to participation in high-risk sports such as whitewater rafting, caving or adventure races.

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

Cited by 14 publications

References 17 publications

Vomiting as a Symptom and Transmission Risk in Norovirus Illness: Evidence from Human Challenge Studies

Vomiting as a Symptom and Transmission Risk in Norovirus Illness: Evidence from Human Challenge Studies

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

Infections associated with adventure travel: A systematic review

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