Several health facilities in Saskatchewan, including a Saskatoon hospital, are under quarantine as officials try to stop an outbreak of norovirus.

A problem was first detected Jan. 5 in a ward at St. Paul's Hospital in Saskatoon. The virus has since shown up in two other areas of the hospital.

"Effective immediately, St. Paul's Hospital is restricting public and visitor traffic from entering the hospital, unless for a scheduled appointment, emergency or for approved visitors to terminally or critically ill family members," the Saskatoon Health Region announced Wednesday in a news release about the outbreak.

The region said 18 patients and 19 staff were affected by norovirus. Officials are now awaiting test results for confirmation of other suspected cases.

The norovirus is a gastrointestinal illness that causes diarrhea, nausea, vomiting and stomach cramps. People in weakened conditions are especially vulnerable to the virus.

"We deal with infections all the time," Sanda Blevins, a vice-president for the health region, told CBC News on Wednesday. "Handwashing is the prevention."

The region said all entrances to the hospital would be secured and staff and doctors would need to show identity cards before entering.

"Norovirus is a type of bug that's prevalent all the time," Blevins said. "It's when it starts to really spike and peak that we get excited."

The last time Saskatoon experienced a similar outbreak was January 2007.

There were also reports Wednesday that the virus had turned up at a long-term care facility in Shaunovan, Sask., where four patients have symptoms.

Visits are also being limited at that facility.

As well, the Parkside long-term care facility was reporting illnesses related to norovirus. And another care home, the Stensrud lodge in Saskatoon, was dealing with it.