[A specific IgM test for the diagnosis of Epstein-Barr virus infections (author's transl)]

IgM antibodies specific for Epstein-Barr virus (EBV) were measured in 302 patients with high IgG antibody titers to study whether EBV was the cause of disease in children having one or more symptoms of classical infectious mononucleosis. IgM antibodies specific for EBV were found in all patients with the defined clinical picture of infectious mononucleosis. In addition the majority of cases with clinical suspicion of the disease had also specific IgM titers. Besides infectious mononucleosis EBV can also be the cause of other diseases like hepatitis, and lymphadenitis: we found IgM antibodies specific for EBV in 48% of patients with nonbacterial lymphadenitis and in 64% of patients with hepatitis not due to hepatitis A or B virus. In contrast to observations by others we were able to show heterophile antibodies in cases with incomplete features of infectious mononucleosis. IgM antibodies to EBV were found in 4 out of 85 controls only. We conclude that untypical features of infectious mononucleosis can be caused by EBV also. Therefore the determination of specific IgM antibodies to EBV can be helpful in the diagnosis of uncharacteristic EBV infections.