Infectious mononucleosis (Mono) is often referred to as the "kissing disease" due to it's manner of spreading from one individual to another. Actually, Mono is caused by a type of Epstein-Barr virus (EBV), a virus that is thought to be responsible for other conditions such as Chronic Fatigue Syndrome. EBV occurs in two forms that are widely prevalent in nature and are not distinguished by conventional tests. Epstein-Barr virus infections occur worldwide. In fact, by adulthood, over 90 percent of individuals have been infected and have antibodies to the virus. Infections occur with greatest frequency in early childhood, with another peak during late adolescence. In areas with lower standards of hygiene, such as those observed in lower socioeconomic classes and developing nations, the infection is seen mostly in young childhood, while in areas of higher standards of hygiene, the infection occurs primarily in young adulthood.

Chronic fatigue syndrome is the current name for a disease that has been described for three centuries. It is characterized by a debilitating fatigue and a variety of other physical, constitutional, and neuropsychological complaints. Certain individuals, who were labeled in the past with various diagnoses ranging from neurasthenia to encephalomyelitis including chronic Epstein-Barr virus infection, are now thought to have chronic fatigue syndrome. The diversity of names is a reflection of the number and controversy of theories of the disease. Whatever the cause, there seems to be several common themes that occur. It is often postinfectious, it is associated with immunological disturbances, and it is frequently accompanied by depression.

A study published in the journal, Pediatrics, screened adolescents during a 2-year period following infectious mononucleosis to determine whether they were more likely to develop chronic fatigue syndrome. The study included 301 adolescents between the ages of 12 and 18 years with infectious mononucleosis who were screened for non-recovery 6 months after having mono by using a phone interview. The adolescents who had not recovered then underwent medical evaluation and were re-screened at 12 and 24 months post infectious mononucleosis. The results revealed that at 6 months 13% of adolescents met the criteria for chronic fatigue syndrome, at 12 months 7% met the criteria and at 24 months 4% met the criteria. It was found that all 13 adolescents with chronic fatigue syndrome 24 months after infectious mononucleosis were female and they also reported greater fatigue severity at 12 months. These findings appear to indicate that infectious mononucleosis may increase the risk of developing chronic fatigue syndrome especially in female adolescents.¹

¹ Katz BZ, Shiraishi Y, Mears CJ, et al. Chronic Fatigue Syndrome After Infectious Mononucleosis in Adolescents. Pediatrics. Jul2009;124(1):189-93.