They fled from a wildfire hundreds of square kilometres in size. Now a growing number of evacuees from Fort McMurray are coping with a microscopic stomach bug.

An outbreak of suspected viral gastroenteritis has doubled to 105 cases as of Tuesday from 40 to 50 a day earlier among people evacuated from harm’s way as fires threatened Fort McMurray and other communities, said Dr. Chris Sikora, Edmonton zone senior medical officer of health for Alberta Health Services.

Sikora said the increase in case numbers isn’t alarming.

“Viral gastroenteritis usually has an incubation period of half a day to two days from time of exposure to time of developing symptoms,” Sikora said. “This isn’t unexpected.”

There are about 75 cases at the Northlands Edmonton Expo Centre, with the rest at other evacuee reception sites. Sikora did not identify the other locations for privacy reasons. As of Tuesday, there were 407 people lodged at the Expo Centre, but 11,700 people are registered to use the facility for food, clothing and other needs.

Viral gastroenteritis is an intestinal infection marked by nausea, vomiting and diarrhea.

People showing symptoms are being kept in a separate hall of the Northlands facility. Medical staff are at the site to offer assistance. Cleaning of washroom and shower facilities have been stepped up and the supply of hand sanitizer has been boosted. Evacuees are also being reminded to wash their hands with soap and warm water before and after washroom visits, before eating and after changing diapers.

Sikora said for most people the illness will be no more serious than a nuisance and replenishing lost fluids is key.

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