Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.See all posts »
Infectious Mononucleosis (Mono) and the Outdoors
There are a number of diseases that are not commonly thought of as outdoor-related afflictions, but all the same, do have implications for persons who engage in outdoor activities. This may be because the diseases limit abilities or because they have effects that are underappreciated or not even recognized. Such is the case with infectious mononucleosis (IM, often reffered to colloquially as "mono"), which is most commonly associated with Epstein-Barr virus (EBV) infection.
An excellent review article in the New England Journal of Medicine (2010;362:1993-2000) by Drs. Katharine Luzuriaga and John Sullivan entitled “Infectious Mononucleosis,” revealed a number of details about the disease. For instance, infection with EBV is lifelong. So, while most cases of IM occur during the first infection with EBV, in some circumstances a person carrying this chronic infection can develop IM later in their life. Furthermore, more than 95 percent of adults worldwide are infected with EBV.
IM most commonly affects those who have a primary (first time) infection during their second decade of life (e.g., teenagers). This appears to be the time when the infection is most commonly spread between individuals. IM is sometimes called the “kissing disease” because the saliva transferred between two people who have kissed can be infectious. The incubation period from exposure to onset of symptoms is felt to be 30 to 50 days.
Symptoms include sore throat and fatigue (malaise, tiredness). The classic presentation is one of sore throat, fever, and swollen lymph glands (nodes) in the neck. Less common symptoms include purple-red spots on the palate, swelling around the eyes, and skin rash. Most victims have an enlarged spleen. Most victims recover without complications, but there can be serious problems, including blood disorders, kidney disease, and neurological complications. IM is diagnosed in most adolescents with a combination of the clinical presentation, the presence of “atypical lymphocytes” identified on a blood smear (on a slide, stained with hematoxylin and eosin), and a positive heterophile antibody blood test. Many cases are missed because testing fails to lead to a definitive diagnosis.
From an outdoor activities perspective, an enlarged spleen can be problematic, because it is prone to rupture. This may occur when there is abdominal or flank trauma or even spontaneously, with an apparent blow to the organ. When a spleen ruptures, there can be severe internal bleeding. The current recommendation is for athletes to avoid exertion (not just contact) for a period of three weeks after the diagnosis of IM is made; splenic rupture has occurred as long as seven weeks after diagnosis. This recommendation seems reasonable for all outdoor activities in which the patient will sustain significant exertion and/or for which there is an expectation of contact or falls.
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