A Norwalk-like virus, causing severe nausea and diarrhea, has caused difficulties for Grand Canyon river runners again this year. In the heat of the Canyon, river runners impacted by this illness are at risk for dehydration.
Recent reports are of a Norovirus spreading among river runners on several river trips, in one instance sickening everyone on a concessions trip except two crew members. Outbreaks of the illness were also reported in 2005 and again in 2010.
Although the exact transmission mechanism has not been identified in this incidence, river runners are reminded that simple precautions can go a long way to decrease the chances of catching this very contagious disease. It is known to spread through the air, as well as by contacting contaminated food and surfaces. An infected person can be contagious even without symptoms or before showing symptoms.
The following are precautions recommended by the Public Health Service:
Treat all drinking water not obtained from a potable source with both filtration and then chlorine since the virus is too small to be filtered out.
All hand wash water should be chlorinated. It is possible that river runners are becoming ill due to Norovirus in the Colorado River water. Hand sanitizers alone are not sufficient to kill the viral cells.
Additionally, chlorine should be added to the first as well as the last bucket in the standard four bucket dish line.
Bare hand contact with all ready-to-eat food such as nuts, cookies and other salty snack food should be avoided.
Finally, river runners are reminded to wash their hands after using the toilet and before eating, where many hands will come into contact with items such as ketchup bottles, salt and pepper shakers, and other multi-use single container items.
River Runners for Wilderness has received an advisory from the National Park Service with suggestions for what actions to take should a Norwalk-like illness impact a river trip. That information is posted here:
http://rrfw.org/RaftingGrandCanyon/Illness_on_the_Water