Parents of summer campers are being assured that recent outbreaks of H1N1 flu are not cause for alarm, even as the number of camps reporting suspected infections rose to six.

The Simcoe Muskoka District health unit says campers at three camps are being clinically tested for H1N1, after reporting unusual levels of flu-like illnesses.

Three other camps in the region already have laboratory-confirmed cases, with 227 children showing symptoms of what is assumed to be H1N1. But all those illnesses have been mild and the number of new cases at the camps is falling.

None of the camps have been closed, though some of the sick children have been sent home.

Besides the Simcoe-Muskoka camps, one in the Haliburtons, just south of Algonquin Provincial Park, and one in the Ottawa area may have experienced cases of H1N1 flu.

"Because of this virus, H1N1, largely affecting younger populations, we will potentially expect to see more outbreaks in summer camps, like we did, during the school season in school children," said Dr. Arlene King, Ontario's chief medical officer of health.

Ontario's health minister, meanwhile, is assuring parents of campers that their kids aren't in danger because of the outbreaks.

David Caplan says he's been told that all affected camps can remain open as long as they continue to follow ministry guidelines around the necessary precautions.

Simcoe Muskoka health officials say the outbreaks are not surprising given what's happening with the H1N1 flu in the broader community.

All the cases in Ontario cottage country so far have been resolving themselves within a matter of days, says Dr. Colin Lee of the Simcoe Muskoka District Health Unit.

"A lot of them have gone home to rest up. It's more comfortable for them to be at home," Lee told said Thursday. "For those who are staying who are ill, they're being isolated from the other campers until they are feeling better."

Some of the camps are now screening all children at bus pickups, with kids who are ill being sent home.

In B.C., an army cadet training centre has also been hit by H1N1. It has cut back on activities after a cadet came down with a confirmed case of swine flu. Three other cadets fell ill just days after summer training had started, and that number has grown to 27. The centre says all the cadets are doing well.

Flu concerns have prompted at least 50 summer camps across the United States to cancel sessions or send campers home early.

The American Lung Association has advised all its affiliated camps to close, after four campers were hospitalized when they became sick at a camp in Julian, Calif.

Dr. Marla Shapiro says kids with asthma or other respiratory diseases are at greater risk from H1N1.

"Not necessarily because the flu might be worse in them - although it might - but their asthma might flare and their underlying health conditions may get worse," she explained to Canada AM.

Dr. Shapiro says she's not surprised that flu clusters are being identified at some camps.

"We talk about hand-washing, but it's hard to get kids to do that. And in the cabins, they have bunk beds that are close together -- none of that six-foot social distancing that doctors talk about for when somebody is sick."

Dr. Lee says he still thinks it's safe for parents to send kids to camp.

"When they arrive, they are screened for illness. And during their stay, the camps are being vigilant to identify campers who may be ill," he said.

Shapiro says she got a letter from the camp she sends her kids to earlier this summer that advised that they were preparing for the flu but also warning that if her children become ill with a fever, they would be sending that child home.

"In all my years that I've been sending my children to camp - and it's many, many years now - I've never seen a letter like this before", Shapiro said.

She added: "Visitors' Day is this weekend for many camps. And if you as a parent are unwell with fever or influenza-like illness, much as you might want to see your child, it's not a good idea to go and bring illness along with you."

With files from The Canadian Press