Mumps could make cross-country jumps, doctors warn

Young adults who may have been exposed to the mumps virus during recent outbreaks should change their behaviour to avoid spreading infection, health officials in several provinces say.

Nova Scotia has seen more than 200 cases of mumps since last February, most of them among students at Dalhousie University in Halifax. As students head to their home provinces for the summer, public health officials say the mumps virusmight behitching a ride in vulnerable hosts and warn it could spread across the country.

"It's probably in that third or fourth wave of cases where students would have scattered after the end of their exams," said Dr. Monica Naus of the B.C. Centre for Disease Control. "So I would expect importation to other parts of the country."

It could be weeks before health officials know how serious the exported outbreaks are.

In the meantime, they advise people who may have been exposed to the virus, including 300 patrons of a bar in Toronto last week, to avoid exchanging saliva: no sharing drinks, food or cigarettes, and kissing is considered especially risky.

Coughing and sneezing also spread the droplets, particularly in crowded dorms and bars, said virologist Dr. Todd Hatchette of Dalhousie.

National numbers tracked by the Public Health Agency of Canada won't be updated until next week. So far, provincial data shows:

• 222 cases in Nova Scotia.
• 44 cases in New Brunswick.
• Onecase in Prince Edward Island.
• Ninecases in Ontario.
• Twocases in Alberta.
• Onecase in British Columbia.

The outbreak of this strain ofthe virusdates back to the fall of 2005 when dozens of Dalhousie students came down with mumps.

When doctors looked at their vaccination history, they determined most had received only one dose of the measles, mumps, rubella or MMR vaccine in childhood. A single shot was common at the time, and two doses did not become standard until the mid-1990s.

Waning immunity

People born between 1970 and 1992represent a lost group of people who have only partial protection against mumps and are most at risk.

"We're finding that with time there is waning immunity," said Hatchette. "Meaning the body loses its ability to neutralize infection if somebody was exposed to the virus."

Nova Scotia is now vaccinating health-care workers to ensure they do not get sick with mumps. It is too late to vaccinate Dalhousie students, and too soon to launch a national booster campaign, Naus said.

"If we do start seeing sustained transmission in adjacent or other jurisdictions, then it will be time to revisit that policy."

Mumps causes swollen and tender glands and other flu-like symptoms, but can also lead to sterility, deafness and viral meningitis. People can be contagious for about seven days before symptoms appear, and up to nine days after.