The Fraser Health Authority issued this map of mumps cases documented in the region in 2008 - up to Aug. 18. (Fraser Health)

An outbreak of the mumps in the Fraser Valley has prompted health officials to warn people to make sure they are immunized against the disease.

As thousands of children prepare to head back to school, the outbreak, which began in a religious community, has already spread westward into Metro Vancouver — as far as Burnaby.

There have been 116 confirmed cases of mumps and another 74 suspected cases since February, according to the Fraser Health Authority. On average, the region has only 10 cases a year.

Two people from Alberta carried the mumps to a religious community near Agassiz that has a low rate of vaccinations, said Dr. Elizabeth Brodkin of the Fraser Health Authority.

"My understanding is their interpretation of scripture is that to immunize would be to show a lack of faith in God's ability to protect them, and therefore they choose not to do that," said Brodkin.

Brodkin wouldn't identify the closely knit faith-based community but said the mumps outbreak since spread well beyond that group.

"The virus is kind of travelling underground and popping up every time it encounters somebody who is able to develop clinical mumps that we recognize," said Brodkin.

Meanwhile, experts from the Fraser Health Authority were meeting to decide whether additional efforts are needed to control the spread of the preventable disease, provincial health officer Dr. Perry Kendall told CBC News Tuesday morning.

As a precaution, Kendall said, people should ensure their immunizations are up to date and avoid sharing drinking gear, straws or cigarettes, because the disease can be transmitted through saliva exchange.