Five players with the Vancouver Canucks are sitting out Saturday's game because they have or are suspected to have the mumps, the team said Friday.
So far only one player, Troy Stecher, has been confirmed to have the virus, said Canucks general manager Jim Benning.
Four other players — Chris Tanev, Nikita Tryamkin, Mike Chaput and Markus Granlund — are under quarantine because they have symptoms.
"We're taking this very seriously given how easily mumps can spread," Benning said in a news release.
"We'll continue to follow all protocols in accordance with the Vancouver Coastal Health guidelines in order to prevent further infection."
The team said health authorities will be at Rogers Arena today "to screen players and staff and immunize those who need it."
A viral infection, mumps is spread through saliva and respiratory droplets. It causes swelling of the salivary glands, which are in your cheeks, close to your jaw and below the ears.
Health officials in several provinces say the disease is making a comeback in Canada and the U.S.
Same source of infection likely
At a press conference later in the afternoon, Vancouver Coastal Health said it could only confirm that one of the five players has had two full doses of the mumps, measles and rubella (MMR) vaccine.
Dr. Reka Gustafson, a medical health officer with VCH, explained that only people born after 1994 have automatically had the recommended two doses.
But a double doesn't ensure full immunization, she explained — it offers 88 per cent protection, as opposed to 78 per cent if only one dose has been administered.
Gustafson said mumps outbreaks do happen periodically, especially when people are living in close proximity.
She said the five Canucks players all presented symptoms within a few days so were likely exposed to the same source of infection.
Worries ahead of Saturday's game
Canucks coach Willie Desjardins said the team was hopeful going into Saturday's game against the San Jose Sharks, but "now we certainly have a few other things we have to worry about as well."
Right winger Alex Burrows said the quarantine was unfortunate, but he was confident the team would be able to forge ahead.
"It's too bad that it affects us right now but hopefully it won't be too long and those guys will be back soon," Burrows said.
This is not the first time a mumps outbreak has hit the NHL.
In 2014, nine players were diagnosed with the disease as the league struggled to contain it. One of the players who contracted mumps that year was Pittsburgh Penguins player Sidney Crosby.