LAS VEGAS (KLAS) — A hiking trip to the Grand Canyon is no time to come down with a serious illness, but a National Park Service (NPS) warning says that’s exactly what has happened to some over the past couple of months.

A warning about gastrointestinal illnesses among Colorado River users and backcountry campers indicates norovirus could be to blame.

“Symptoms include nausea, stomach cramping/pain, vomiting, and diarrhea. These symptoms are consistent with norovirus, and we have confirmed norovirus from at least one rafting trip,” according to a May 20 advisory on the Grand Canyon National Park website.

The warning follows a May 15 Facebook post that gives an account of a rescue in the canyon. Although a helicopter couldn’t land to bring a group of hikers out, rangers were able to get water to the group and make sure they had the assistance they needed to get to safety.

One ranger thanked a hiker named Kristi Key, who alerted authorities and helped rangers locate the group. “Can I just shake your hand and say thank you for doing this. Thank you for saving this man’s life,” one of the rescuers told Key.

The post said norovirus had been rampant in Grand Canyon Village leading up to the incident.

The NPS advises that norovirus is contagious, and has posted instructions on how to properly filter water before using it in the wild.

NPS also advises:

  • If you are ill or have been ill within the last 72 hours, do not join a group trip. If you become sick, stay away from others and keep your distance from anyone in your group who is ill.
  • Wash your hands regularly, particularly before and after using the toilet and before eating meals. Handwashing with potable or treated water and soap is preferable to using hand sanitizer. Hand sanitizer should have at least 70% alcohol. Ensure hands are appropriately dried with a clean paper towel.
  • 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.
  • 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.
  • During visits to water features throughout the canyon (e.g., waterfalls, pools, streams, side canyons) do not drink from non-potable water sources.
  • Use designated toilet areas when you need to use the bathroom.