INFECTIOUS MONONUCLEOSIS (MONO) AND SPORTS PARTICIPATION

Infectious Mononucleosis (IM), better known as “mono” is a medical condition that affects thousands of athletes annually.  This condition can present itself in a variety of ways and will often resolve on its own without complications, but there is the rare risk of splenic rupture.  Splenic rupture if not addressed immediately via surgical removal of the spleen can be fatal.  Given this possibility, it is important for sports medicine professionals and parents to take reasonable precautions based on available evidence when returning athletes to activity following IM.

The American Medical Society for Sports Medicine has developed and published a consensus statement regarding infectious mononucleosis and athletic participation.  The citation for the positions statement is as follows:

Putukian, M., O’Connor, F.G., Stircker, P.R., McGrew, C., Hosey, R.G., Gordon, S.M., Kinderknecht, J., Kriss, V.M., and Landry, G.L. (2008).  Mononucleosis and athletic participation:  An evidenced-based subject review.  Clinical Journal of Sports Medicine, 18(4), 309 – 315.

According to this statement, currently there is no evidence to suggest that IM is more prevalent in the athletic population than in the non-athletic population.  The infection is most common in adolescents and young adults with an average infection rate of approximately 15% of the previously unexposed individuals.

Some of the major highlights from the article:

HISTORY AND PRESENTATION:

•           The condition is typically spread through oral secretions often spread by sneezing, sharing drinking glasses or food.
•          Symptoms can last anywhere from 4 – 6 weeks, some cases have been known to last as long as 3 months
•          Most common symptoms include fever, lymphadenopathy (swollen glands) and pharyngitis (sore throat).  Other symptoms can include headache, rash and spleenomegaly (enlarged spleen).
•           Keys to referral for further evaluation would be prolonged fever and lymphadnopathy

COMPLICATIONS:

•            Severe complications only occur in approximately 5% of all IM cases
•           The most familiar complication is splenic rupture, but there are others
•           Splenic rupture is estimated to occur in 0.1% - 0.2% of all cases and can occur spontaneously, meaning a specific trauma is not required to cause rupture
•          Typically most ruptures occur within the first 3 weeks of illness, and about half of those were spontaneous

RETURN TO PLAY GUIDELINES:

•          Exact guidelines for return to play are difficult with IM because there is no ideal laboratory or imaging technique that can confirm the status of the spleen or the resolution of the illness via virus levels
•          Based on current available evidence regarding the potential for splenic rupture return to non-contact activities can be a gradual progression assuming the athlete no longer has a fever and can tolerate aerobic activities
•          For return to contact activities, suggestions are much more difficult; minimally the athlete should be held out for at least 3 weeks where the likelihood of rupture is believed to be minimal and other indicators are present to allow for a safe return

Returning athletes to activity following a bout with IM can be highly challenging given the lack of clear return to play guidelines.  Parents should be aware that when returning from activity the risk of splenic rupture is very rare decreases significantly after 3 weeks based on current research, but it is never zero until the illness has completely resolved.  Parents should also be aware that physical exam for an enlarged spleen is highly ineffective.  If examination of the spleen is deemed necessary the standard evaluative technique is ultrasound, but a computed topography (CT) scan is also a possibility depending on the needs and preference of the physician.  Be sure to address any concerns you have with your athlete’s physician as they prepare to return to activity following a bout of IM. 

Whether splenomegaly (enlarged spleen) is of concern or not, the athlete’s return to activity should be gradual, based on their level of fatigue and other symptoms.  A gradual fitness program means progressing not only from shorter to longer periods competing in activities, but also considering the intensity of exercise.  This means, progressing how hard the athlete is working from 50% or so up to 100%.  The program can be progressed over several days to weeks depending on how the athlete responds to training.  The key to remember is that the degree of fatigue the athlete experiences the day after a training session will let you know whether s/he can handle an increase in activity (whether that is time or intensity) or not.

Submitted by Heather L. Clemons, MS, MBA, ATC