Gastrointestinal Illness Alert
June 25, 2022 Update
The National Park Service Office of Public Health has received reports of gastrointestinal illness among >150 private and commercial river rafters and back-country campers during April and May 2022. Symptoms include nausea, stomach cramping/pain, vomiting, and diarrhea. These symptoms are consistent with norovirus, and we have confirmed norovirus from at least eight rafting trips.
Comprehensive control measures have been implemented, and since early June, there has been a marked decrease in reports of illness. We are continuing to monitor and investigate the situation in collaboration with partners at Coconino County Health and Human Services and the Centers for Disease Control and Prevention (CDC).
Norovirus is a highly contagious virus - you can get norovirus from an infected person, contaminated food and water, or by touching contaminated surfaces. Norovirus causes sudden-onset vomiting and diarrhea that lasts 1–3 days. On rafts and in camps, norovirus can spread quickly. The best way to prevent norovirus is to practice proper hand washing and general cleanliness and ensure the safety of your drinking water. More information on norovirus is available at CDC’s website >
Practices to Prevent Norovirus Transmission:
If you are ill or have been ill within the last 72 hours, do not join a group trip. If you or others in your group become sick, minimize interactions between ill and healthy individuals. Use separate camping and rafting equipment when possible.
Avoid sharing food and drinks and putting your hands into shared food sources. Pour food into individual plates/bowls and do not share food, plates, cups, or utensils. Don’t touch the nozzle of water dispensers. Individuals with any sign of illness should avoid preparing or handling food for the group.
Wash your hands regularly, particularly before and after using the toilet and before eating meals. Hand sanitizers are not as effective as washing hands with water and soap at removing norovirus particles. When handwashing is not an option, use a hand sanitizer with at least 70% alcohol.
Ensure water is not only filtered, but also chemically disinfected, as point-of-use filters will not remove norovirus from your water. Alternatively, boil your water to a rolling boil for at least one minute (or at least 3 minutes at elevations above 6,500ft). Of note, it is safe to consume water from spigots or park-provided fountains." More information from the CDC on safe drinking water is available here >
During visits to water features throughout the canyon (e.g., waterfalls, pools, streams, side canyons) do not drink from non-potable water sources. When recreating in these sources, be vigilant not to consume water.
Closely monitor yourself for signs and symptoms of gastrointestinal illness throughout the duration of your trip, including for nausea, vomiting, diarrhea, or stomach cramping. Informing your guide of symptoms as soon as they occur can help them keep you safe and contain the spread. See the illness management section for more details.
Use designated toilet areas when you need to use the bathroom. If a restroom is not available, all human body waste solids should be contained and carried out using a portable toilet or a specifically engineered bag waste containment system (capable of being sealed securely and containing enzymes and polymers to treat human solid waste). Vomit should also be contained in a sealable container and carried out of the canyon.
Norovirus can cause severe dehydration, especially in combination with the extreme heat and physical demands of the canyon. Symptoms of dehydration include dizziness, fatigue, headache, and muscle cramps. Managing hydration with both water and electrolytes (e.g., from salty foods or sports drink mixes) is essential. More information on hydration management is available here >
While traveling in the backcountry, river running, or hiking, you may need to use water from the Colorado River, side streams, pools, springs, or other sources. There may have been a time when it was safe to use such sources, but no longer. Any untreated water has the potential to cause illness if it is not properly and carefully disinfected.
Wash your hands prior to collecting the water. It does no good to treat your drinking water if you are going to recontaminate it.
Silt particles inhibit disinfection. If the water is muddy or cloudy, allow the particles to settle undisturbed for several hours. Alternatively, add a small amount of a clearing agent such as alum (aluminum sulfate). The suggested dosage for alum is 1/5 teaspoon per gallon. Mix vigorously and allow to sit for five minutes, stirring twice. Once the silt has settled, either pour the cleared water into another container or draw directly from the top.
Filter the clear water through a minimum of an absolute 1-micron filter or one labeled as meeting American National Standards Institute (ansi/nsf) International Standard #53 for "Cyst Removal."
Filtration alone is not sufficient to guarantee safe water. Disinfect the filtered water by adding two drops of household bleach or five drops of tincture of iodine per gallon of water. After addition, allow the water to sit for 30 minutes to give the chemical time to kill any organisms. Very cold water should rest even longer. Another option is to follow the manufacturer's instructions for commercially prepared products.
Bring the Cleared Water to a Roiling Boil for One Full Minute.
At elevations above 6500 feet (2000 meters), such as on the canyon rims, increase the boiling time to three minutes.
Treated water must be stored in clean and sanitized containers.
Everyone has preferences and beliefs that may affect personal decisions. If you are on a commercial river trip or hike, the guides are required to follow the correct drinking water disinfection procedures. If you are on a private river trip or hike, the National Park Service strongly encourages you to follow these same procedures. While some waterborne illnesses may be mild, individual reactions and responses to disease agents vary. All disease agents can cause severe or life threatening illness in some people.
If you have questions regarding drinking water, or if you have become ill while traveling in the Grand Canyon backcountry, please contact: Park Sanitarian (928) 638-7355 or Backcountry Information Center (928) 638-7875.
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