Detection of IgM antibody to Epstein-Barr virus, 1999-2006: analysis of data collected at a commercial diagnostic laboratory in Japan

The status of infectious mononucleosis in Japanese youth has been little studied. To gain more information, we analyzed data from tests for Epstein-Barr virus-specific IgM in about 180,000 serum specimens sent to a commercial diagnostic laboratory from clinics nationwide between 1999 and 2006. The IgM antibody to the viral capsid antigen (VCA) was assayed by indirect immunofluorescence with P3HR-1 cells. In an age-distribution graph of IgM positive specimens, two peaks were found both in young children and youth. Boys outnumbered girls in the group of children aged 0 to 3, and vice versa in the group of youth aged 15 to 25. IgM-positive specimens increased from spring to autumn only in the youth group, suggesting that infectious mononucleosis in this group occurs more during this time. Infectious mononucleosis symptoms are more severe in youth, and further epidemiological studies are needed to clarify the disease status in young Japanese adults.