NHL's Mumps Outbreak Might Not Be Over Yet

— -- More than a dozen NHL players and referees have contracted mumps in recent weeks, with additional players tested amid fears that the disease could spread.

Players with the Anaheim Ducks, New Jersey Devils, New York Rangers, Minnesota Wild and Pittsburgh Penguins have been affected so far. The viral infection can cause swelling of the salivary glands, fever, headache, fatigue and loss of appetite.

Mumps can be spread by sneezing and coughing, and it can spread quickly in close quarters, with hockey’s physicality and locker room culture aiding in the outbreak. Because mumps has an incubation period of up to three weeks, doctors say, it will take some time to know when the league’s outbreak is over.

Penguins forward Beau Bennett, who was tested Monday, is the latest player to be screened for mumps.

Days earlier, Bennett’s teammate Sidney Crosby appeared in the locker room with a swollen face, a tell-tale sign of the disease. Crosby is past the infectious stage and could return to the team as early as today, Penguins officials said.

Bennett was tested four days after he and other Penguins players visited the Children’s Hospital of Pittsburgh to spread Christmas cheer.

In a statement to ABC News, the hospital said it plans to isolate patients and families who visited with Bennett and who had not received their age-appropriate doses of mumps vaccine, and will be monitoring them.

Children with immune problems are at a greater risk to have severe infections from the mumps.

Mumps was nearly eradicated in 1967, but made a re-emergence in 2000. A notable outbreak occurred in the Midwest in 2006, when thousands of college students were infected.

Americans are vaccinated against the mumps as part of the measles, mumps and rubella (MMR) vaccine, the first dose of which is given to babies between 12 and 15 months old, according to the Centers for Disease Control and Prevention. The second dose is given at 4 to 6 years old.