Mumps makes a comeback in Canada and the U.S.

The recent rise in Canadian cases of mumps and its complications have led public health officials in several provinces to remind young adults to check if they need vaccination boosters.

Mumps is a viral infection that is contagious and spread throughsaliva and respiratory droplets, and causes swelling of the salivary glands, which are in your cheeks, close to your jaw and below theears.

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Mumps "can also be associated with deafness, meningitis," said Dr. Sarah Wilson, medical epidemiologistwith Public Health Ontario. "There are significant complications but fortunately for most people, it's an unpleasant, uncomfortable experience that resolves."

A person with mumps is most infectious from seven days before to five days after they have symptoms, which can also include headache and fever, according to health officials. You can contract mumps bybreathing around the coughor sneeze dropletsof someone who is infected, or by sharingcups and other objects that have been handled by someone with the disease.

So far this year in Ontario, there have been 19 cases, Wilson said, compared with the usual annual count of five to 23.

Toronto Public Health has logged at least 17cases since January, far above the four cases annually that have been logged over the past five years.

All of the cases have been confirmed in adults aged 18 to 35.

The investigation focuseson bars on the west side of downtown. About 60 per cent of those infected either never received the mumps, measles and rubella booster or only got one of the two recommended doses, said Dr. VinitaDubey, acting medical officer of health.

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Providing a second round of the vaccine wasn't practised until the early 1990s, which has led to a small gap in the herd immunity for those born between 1970 and 1994.

Anyone born before then likely had the mumps as a child, Dubey said, and is considered immune.

Health officials in the Halifax area say acase of mumps and seven measles caseshave been reported. Both infections are covered by the same combination vaccine.

Hockey players infected

In Medicine Hat, Alta., there werenine confirmed cases of mumps, Dr. Vivien Suttorp, medical officer of health for Alberta Health Services, said All wereconnected to hockey.

The first Western Hockey League player to be diagnosedplays for the Brandon Wheat Kings in Manitoba.

Since Sept. 1, 164 confirmed cases of mumps have been reported to health officials in Manitoba. The province typically experiences four to five cases every year.

Medicine Hat Tigers right-winger John Dahlstrom, 20, said he woke up with a swollen neck before he was diagnosed.

"It was bad for about two days," Dahlstrom said. "I had fever and a real hard time eating, hard to swallow food, and then after that I started feeling good again."

Alberta health officials are also investigating four possible cases of mumps in the Edmonton region.

Suttorpsaid that in adults, disease symptoms such as fatigue, headaches and gland swelling can be worse. Complications can include swelling of the testicles that in rare cases can lead to sterility, and swelling of the ovaries.

People can be infectious for two to five days before the cheek swelling, said Dr. Monika Naus, medical director for immunization programs at the BC Centre for Disease Control.

That's why guidelines recommend that infected individuals self-isolate for nine days, and the first five days in particular, Naus said.

"You can have meningitis from this and I think that everybody probably feels that, 'Do I want aninfection around my brain? Not really.'"

The effectiveness of two doses of the measles, mumps and rubella vaccine is about 88 per cent, Naus said.

"In terms of the picture of mumps and our questions about how do two doses of mumps-containing vaccine offer protection, I think the scenarios where it's most challenging are where there are a lot of people, a lot of crowding and then the opportunity for sharing food and drink," Wilson said.

Bars were also the epicentre for outbreaks in Nova Scotia in 2007 and in 2016 in Whistler, B.C.,Naussaid.

Previous outbreaks

While most of B.C.'s cases of mumps in recent years were probably among those who had a single dose of the vaccine, cases can also occur among people who've received both doses, as happened in the case of Pittsburgh Penguins starSidney Crosby in 2014, when other NHL players also were diagnosed with mumps. (Born in 1987, Crosbyreceived only one dose as a child. He got a booster when he wasabout to travel to the Sochi Winter Olympics.)

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In the U.S., federal officials said Thursday they are looking into whether mumps immunity decreases over time and whether there would be benefits to a third dose.

Cases increased in the U.S. last year, reaching 5,300 mainly in Arkansas, Iowa and Oklahoma. So far this year, the high numbers have continued, mostly in Arkansas and Missouri, according to the U.S. Centersfor Disease Control and Prevention (CDC).

"Although the disease has not been serious, the disruption and expense it has caused for local and state health officials has been significant," said Mona Marin, a viral diseases expert with the CDC.

While there hasbeen talk of offering three doses of the vaccine during outbreaks on college campuses in the U.S., Naus said, that doesn't fit the picture of community-based outbreaks that have occurred in B.C.