Outbreaks of infectious diseases like mumps and measles in Canada are causing worry about the possible re-emergence of serious infections like polio, which is trying to make a comeback in other regions around the world.
Across Canada, cases of the mumps are popping up, as health officials have started warning citizens to make sure their immunizations are fully up to date. In Ontario, 19 cases of mumps have been reported in the Toronto area, well above average compared to recent years, while in Manitoba, 176 cases are now confirmed, where the province normally sees only four or five a year.
Many of the outbreaks have been tracked to environments with close contact between people, such as university dorms, hockey and football teams and even crowded bars. A highly contagious disease, mumps is spread through contact with saliva or mucus of an infected person and can be passed by coughing, sneezing or talking.
But along with mumps, cases of the measles have been emerging across the country, with an outbreak in Nova Scotia recently registering seven cases in young adults in the Halifax area. One of the problems with these infections is that people can spread the virus without knowing they’re doing so. The mumps, for example, has an incubation period of about two weeks and symptoms do not crop up (if at all — one third of those infected don’t show symptoms) for two to three days after a person is well able to infect others.
The rise in outbreaks is leaving some asking why now? Part of the problem is a lack of herd immunity for some diseases —that proportion of a society’s population which needs to be immunized to keep individual cases of the infection from becoming an outbreak. Statistics have shown that vaccination rates have dropped both in Canada and the United States, in part due to a hesitancy among some parents to getting their children immunized. The fear of vaccination has been drummed up through spurious research claims about links between vaccines and autism, with opposition to vaccination being voiced over the years by prominent celebrities.
But maintaining herd immunity and high levels of vaccination is crucial. Polio, a disease on the brink of being eradicated from the planet, is currently known to be endemic to just three countries, Pakistan, Afghanistan and Nigeria, all as a result of worldwide vaccination efforts. Yet, a loss of herd immunity could threaten other countries.
In 2014, the World Health Organization declared a global health emergency concerning polio, urging countries where the cases of the disease were arising to work harder to keep vaccination rates high. “Things are going in the wrong direction and have to get back on track before something terrible happens,” said Gregory Hartl, a WHO spokesman to the New York Times. “So we’re saying to the Pakistanis, the Syrians and the Cameroonians, ‘You’ve really got to get your acts together.’ ”
For now, the cause for the higher rates of mumps in North America is still a mystery. In the US, where mumps cases are the highest they’ve been in ten years, health authorities are chalking up the spike in outbreaks to the cyclical nature of the virus, coupled with a suspected waning of the power of the mumps vaccine itself, which is thought to become less effective over a ten to 15 year period. “The virus is always out there,” says Paul Offit, a paediatrics professor at The Children’s Hospital of Philadelphia to Scientific American. “The most likely reason for these outbreaks is that vaccine immunity is fading.”