Canada took home a record 14 gold medals from its own Winter Olympics this year, but health officials say the northern nation also walked away with a less-welcome souvenir: 85 cases of measles.
International visitors were the likely sources of a British Columbia outbreak that began on March 9, nine days after the closing ceremonies of the Olympic games in Vancouver, said Dr. Monika Naus, associate director of epidemiology with the British Columbia Centre for Disease Control. The incubation period for measles is typically 7 to 18 days.
“I think it was quite a surprise to us,” said Naus, who is expected to report Friday at a meeting of the Infectious Diseases Society of America. “There had been a sense in Canada that we had achieved rates of measles elimination.”
Previous years saw four cases or less
Before the lavish games, which attracted 60,000 visitors to the opening ceremonies alone, there were fewer than four cases of measles a year reported in British Columbia since 2002. In 2007, for instance, only two cases were reported.
Don't miss these Health stories
More women opting for preventive mastectomy - but should they be?
- Larry Page's damaged vocal cords: Treatment comes with trade-offs
- Report questioning salt guidelines riles heart experts
- CDC: 2012 was deadliest year for West Nile in US
- What stresses moms most? Themselves, survey says
- More women opting for preventive mastectomy - but should they be?
But in the weeks after the games, laboratory tests confirmed that dozens of people were falling ill with two strains of the highly contagious virus. The outbreak lasted through April 28.
Many of the victims were young adults who became infected at the rowdy outdoor celebrations that sprang up in downtown Vancouver, Naus said.
“None of the cases, as far as we were aware, went to ticketed winter events,” she said.
Most of the measles cases were distributed among three groups: babies too young to be immunized, unvaccinated children and young adults who hadn’t received a second booster shot of measles vaccine as teenagers, Naus said.
Overall, about 35 percent of the measles sufferers were unvaccinated, and another 36 percent didn’t know if they’d been immunized. About 23 percent of the cases were aboriginals, native people who make up about 5 percent of the overall population and tend not to be vaccinated. Eight cases of measles occurred early in the outbreak in one large aboriginal family, Naus said.
About 60 percent of those who contracted measles sought medical care, and 20 percent wound up in the hospital. One patient was admitted to an intensive care unit.
Sports events can spread measles
This isn’t the first time that measles have cropped up at international sporting events. In the U.S., for instance, a 12-year-old Japanese baseball player turned up with measles at the 2007 Little League World Series. Seven people in four states were infected either directly by the boy or by someone he infected.
In Canada, health officials knew there was a chance of an outbreak, Naus said.
“We did discuss it in advance of this and we did stockpile extra vaccine,” she said. “I don’t think it’s an unanticipated event, it’s an unwelcome event.”
The outbreak was the largest in British Columbia since 1997, when 247 measles cases were reported, mostly in college students. That spike came a year after Canada launched an all-out effort to eradicate measles by targeting children and teens in kindergarten through high school with a single dose of vaccine. A second routine dose was added a year later.
That effort has largely wiped out measles in the country, where nearly 88 percent of children have had two doses of the MMR vaccine — measles, mumps, rubella — by the time they enter kindergarten.
But in Canada, as in the U.S., the disease has not been eradicated, mostly because not everyone gets vaccinated. Some parents refuse to vaccinate their children for fear of adverse reactions, Naus noted, and the post-Olympic outbreak is a reminder that infection remains just a plane ride away.
“It does tell us we have these gaps in immunity,” she said.
© 2013 msnbc.com Reprints