Let’s begin with a little detail on a current viral outbreak and finish with the indoor environment:
Since October 17th, 16 NHL players and 2 referees have had confirmed mumps cases. The first diagnosed case was from a Minnesota Wild player, and then 4 other Wild players were subsequently diagnosed as well. Since then, players for the Anaheim Ducks, Pittsburg Penguins, New York Rangers and New Jersey Devils have also had confirmed diagnoses. Other potential cases/players are currently under surveillance, but even if the ‘outbreak’ is limited to the 16 players that have been confirmed as of December 19th, 2.3 percent of the NHL has thus been infected with the mumps virus. Players have been or are currently in quarantine, the NHL has started to reach out to the CDC for help and also re-issued messages to teams about how to prevent and treat the illness.
As a reminder, the MMR (or now MMRV) vaccine has been around since the 1960’s and has been shown to be 78% effective as a single dose and 88% effective if the suggested two-dose regimen is adhered to. With the herd immunity additive effect, disease rates have been reduced by 99% since the induction of the vaccine.
Several things piqued my interest about the outbreak (although I enjoy many sports, hockey is admittedly not my favorite). First off, the virus seems to have spread, assuming the outbreak in question is all the result of one initial infection, BETWEEN teams. Spread within a team of an illness happens all the time, but for a virus that is spread via respiratory droplets/aerosols (saliva/sneezing/shared liquids), I find it interesting that 5 different teams (as well as referees) have been infected. Rarely will water bottles be shared between teams and at the NHL level stadiums are equipped with home and visitor locker rooms, which would limit instances sink, shower or ice bath-mediated transfer. One might suggest that the physicality (read hitting) of hockey gives chances for intimate contact and spread. However, many players now wear facemasks and mouth guards that would limit exchange of saliva during fights or hits. Secondly, there has yet to be mention of family members of the infected, facility workers or fans/attendees of the games to have come down with the virus. Although it is less of a media headline that Sidney Crosby’s significant other may have come down with mumps, I assume some of these reports would have emerged. Lastly, and to the MicroBEnet audience potentially the most important, the NHL plays in an indoor environment.
The hockey rink (indoor) environment has previously been shown to cause airway dysfunction in ice arena athletes. As compounding factors, colder, less humid environments have been shown to allow certain infectious agents to survive longer in the air or on fomites. Cold, low humidity environments have also been demonstrated to exacerbate immune dysfunction in ‘winter’ sport athletes. Lack of direct sunlight and limited direct cleaning of surfaces may also attribute to pathogen survival.
Although general protective measures such as quarantining infected athletes and distributing information may be helpful, maybe the NHL should look into modifications to ice maintenance, temperature/humidity regulation and ventilation in order to limit the current outbreak and prevent future outbreaks. The costs needed to research many of these aspects of disease prevention are probably a fraction of those the NHL loses for star players like Sidney Crosby being sidelined for multiple games.
CDC information on mumps vaccine, ice rink air quality publications and Mayo Clinc on exercise-induced asthma: