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Hockey players may be used to toughing out sore muscles and even odd swellings in the head area — but it’s not injuries that are keeping some players off the ice this fall — it’s mumps.

The virus better known for keeping lumpy-faced children of generations past in bed is making its way through the National Hockey League, forcing booster vaccination efforts, locker-room disinfections and lectures about hygiene.

The latest victim: defenseman Ryan Suter of the Minnesota Wild, who was out last week.

Nine players have been knocked down by the virus, according to Canadian Press: Suter, Keith Ballard, Marco Scandella, Jonas Brodin and Christian Folin of the Minnesota Wild; Corey Perry, Clayton Stoner and Francois Beauchemin of the Anaheim Ducks; and Tanner Glass of the New York Rangers.

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"It is certainly an outbreak that was unexpected and has caused unwanted disruption at the team level, but it is not something we have any significant control over," NHL Deputy Commissioner Bill Daly said in a statement.

"As long as our clubs are doing what they need to do to minimize risk of contraction, we are hopeful that the wave of cases will run their course and life will return to normal in the relatively near term."

Mumps, spread by coughs and sneezes or by sharing cups or cutlery, can spread before and after people know they’re sick, so it can be hard to track it. Sports teams are at special risk of spread because of their prolonged close contact.

It causes the typical flu-like symptoms that so many viruses, do — aches and pains, headaches and tiredness. But mumps' signature symptom is a swelling of the salivary glands that can make the victim's face look swollen and lumpy.

Doctors blame waning protection from the vaccine. Immunizations against measles, mumps and rubella or German measles have been combined in a single vaccine, called MMR, since 1971. Virtually all kids get it but measles and mumps especially can cause outbreaks if large groups of people don’t vaccinate their children or when people’s immune responses to the vaccine wear off.

Dr. Craig Milhouse, the team physician for the Ducks, said the team’s members would get booster shots.

The CDC recommends that adults aged up to about 55 get one or two doses of MMR if they didn’t get it as kids.

IN-DEPTH:

-- Maggie Fox