MOSES LAKE - Moses Lake School District officials canceled Friday classes at Longview Elementary School following an apparent outbreak of stomach flu.

District superintendent Michelle Price said Thursday about 25 to 30 percent of Longview's students were sick. Students and staff were experiencing fever, nausea, diarrhea and vomiting, Price said.

The outbreak is not connected to the recent spike in whooping cough cases, said Theresa Adkinson of the Grant County Health District.

Adkinson said health district officials were treating the outbreak like a norovirus-like illness, "a viral infection with a pretty quick onset." Symptoms usually appear within 12 to 48 hours of exposure, Adkinson said.

As a result the building is closed today so it can be cleaned and disinfected, Adkinson said. The health district recommended steam-cleaning carpets and disinfecting all surfaces, Price said.

The building is scheduled to reopen Monday, Price said. The only way to know if the outbreak has run its course is to open the building and see what happens, she said.

"It is likely that more students or staff and possibly other community members will become ill in the near future, as norovirus-like illnesses are very infectious," Adkinson wrote. She urged people who are ill to stay home and stay away from family members who aren't sick.

People who come down with the disease should stay home for a minimum of 48 hours after the vomiting stops, Adkinson said, and patients should stay home even longer if fever or other symptoms persist.

"The sickness is usually brief, lasting one to three days," Adkinson wrote. The virus is most commonly spread by touching contaminated surfaces, she said, consuming contaminated foods or liquids or by direct contact with a person showing symptoms.

The best way to prevent the spread of the disease is to wash hands with soap and warm water before handling food or ice, before eating, and after using the bathroom, she said. Hand sanitizers aren't a substitute, Adkinson said

Surfaces should be disinfected with soap and water, and then bleached with a 10 percent solution, 1-1/2 cups of bleach to 1 gallon of water, Adkinson said.