Officials at the B.C. Centre for Disease Control have confirmed 46 cases of swine flu so far in B.C. (CBC)

Seven more cases of swine flu were confirmed in B.C. on Tuesday, but the number of infected residents may be much higher because of an outbreak at a school in northern B.C.

The B.C. Centre for Disease Control confirmed 46 individuals in the province have so far tested positive for the H1N1 flu strain that has caused the illness in Mexico, the U.S., Canada and more than 20 other countries.

But Northern Health's chief medical health officer Dr. David Bowering said there may be dozens of unconfirmed cases among the students of Decker Lake Elementary School, west of Prince George.

On Monday, tests confirmed three students at the school had swine flu after about two dozen students called in sick Friday. Those three test results provided enough evidence to conclude more than 30 sick students likely had swine flu, Bowering confirmed Monday afternoon.

That would put B.C.'s unofficial count of suspected and confirmed cases at close to 80 cases.

Bowering said the situation in Decker Lake is a true outbreak and is different from the situation in other areas, where cases are isolated and not widespread.

"Around the world, most of the clusters have been in elementary school and younger populations. That may be something that allows it to spread more readily," he said.

School officials say two Decker Lake students had recently travelled to Mexico, but epidemiologists have yet to confirm that is how the virus was to brought to the community.

The remaining students won't be tested individually. Instead, they are being asked to stay home until they recover, and the school has been closed for the rest of the week. Health officials say anyone who is sick should stay home for at least seven days — longer if their symptoms persist.

Beairsto Elementary in Vernon, B.C., also remains closed until next week after a student tested positive for the swine flu.

So far all of the confirmed and suspected case of swine flu in B.C. have been mild and nobody has required hospital treatament.

That led health authorities in Vancouver to declare Monday that the disease is not as serious as once feared, after initial reports raised fears of a high mortality rate when the virus was detected in Mexico.