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Toronto is dealing with the biggest mumps outbreak the city has seen in at least 25 years, while officials in Nova Scotia say the number of measles cases tied to a recent outbreak now numbers 13 individuals. A number of factors are contributing to the problem, including the fact some people continue to question vaccines, despite overwhelming evidence of their efficacy and safety. While public health messages continue to emphasize the importance of vaccinating children and adolescents, Toronto officials are preparing to target adults in their 20s, 30s and 40s who may not realize they are at risk of contracting mumps because of the way vaccination programs were set up when they were children.

Toronto's mumps outbreak

Toronto Public Health says there have been 68 confirmed cases of mumps in the city since January – a major jump compared to previous years. Typically, the number of mumps cases in a year will be four. The previous highest number was 34 cases in 1995, followed by 33 cases in 2009 and 31 cases in 2010, according to Toronto Public Health. The vast majority of the individuals affected by this year's outbreak are between 18 and 35, with a handful of cases involving staff or students of elementary and high schools. Many of the cases are linked to about two dozen bars in the west end of downtown Toronto, with individuals in that age cohort likely transmitting the infection by being in close proximity, sharing food and drinks or coughing and sneezing near one another, said Vinita Dubey, associate medical officer of health with Toronto Public Health.

Eleven per cent of cases in the current mumps outbreak are tied to individuals who were intentionally not vaccinated, Dr. Dubey said.

But among the adults, the reason why there's so much transmission is that many in the age group weren't fully vaccinated against mumps and, in some cases, measles by today's standards. When Ontario's vaccination program began in the 1970s, children received one dose protecting them against measles, mumps and rubella. In the 1990s, several measles outbreaks led officials to realize two doses were likely necessary to offer full protection, according to Sarah Wilson, a medical epidemiologist at Public Health Ontario. She said the province conducted a major catch-up campaign in 1996, providing a second measles vaccine to school-aged children and adolescents, as well as permanently changing the vaccine schedule to ensure all children get two doses. (Similar catch-up campaigns were run in other provinces for those age groups around the same time.) In 1998, measles was officially eliminated from Canada, meaning there is no longer local transmission of the illness. While measles cases and outbreaks continue to occur, they are linked to international travellers who bring the infection here and spread it to those who are unvaccinated or under-vaccinated.

But the 1996 catch-up campaign only focused on measles and did not provide those young people with a second dose of the mumps vaccine. Nor did it apply to those who were no longer in school in 1996. For this reason, public health officials have been urging people in their 20s, 30s and 40s to check their vaccination records. But this can be a difficult, onerous process, Dr. Dubey said.

"They themselves have no idea about their vaccination history. They are at risk and they're getting [mumps]," she said.

As a result, Toronto Public Health says it is now changing tactics and will actively target individuals born between 1970 and 1992, urging them to talk to their doctor about getting a second dose.

"We're changing the message to more a call to action," Dr. Dubey said.

Measles in Nova Scotia

Meanwhile, officials in Nova Scotia are monitoring an ongoing outbreak of measles that has so far affected 13 individuals. Gaynor Watson-Creed, Nova Scotia's deputy chief medical officer of health, said the source of the outbreak is linked to international travel and that the other cases are all linked to it – such as people who got measles after being in the same location as the infected individual. Several of the cases involve people who were vaccinated, she said. The vaccine is only 97 per cent effective, which helps explain why people who were vaccinated have become sick. Usually, those individuals experience a milder form of the measles, Dr. Watson-Creed said.

She added that vaccine rates are estimated to be around about 85 per cent for school-aged children in the province, which is "relatively high." But the recent outbreak illustrates the need to stay vigilant. Measles spreads incredibly easily. According to Dr. Wilson, if a person with measles is in a room and then leaves, an individual entering that room two hours later could still catch the illness.

Bottom line

Vaccination is, by far, the best way to make sure you and family are protected against preventable illnesses such as measles and mumps. Some people challenge the safety of vaccines, citing flawed studies and bogus evidence to bolster their claims. But as the recent outbreaks show, these illnesses are virulent and need to be taken seriously. In some cases, measles and mumps, not to mention whooping cough or other vaccine-preventable diseases, can lead to serious complications and even death. Ensuring your vaccinations are up-to-date is key to reducing those risks.

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