Positive Epstein-Barr virus and cytomegalovirus IgM assays in primary HIV infection

We report three cases with misleading cytomegalovirus (CMV) or Epstein-Barr virus (EBV) immunoglobulin M (IgM) results during primary human immunodeficiency virus (HIV) infection. We determined the rate of positive anti-CMV IgM assays or anti-EBV capsid antigen IgM assays in sera from a group of well-characterized subjects with primary HIV infection as 2.9% (1/35; 95%CI: 0.15-16.6%) for each infection. The rate of positive anti-EBV capsid antigen IgM assays in subjects with positive hepatitis A virus IgM assays was 30% (6/20; 95%CI: 14.6-51.9%). Clinicians need to consider the limitations of IgM assays for diagnosis of herpesvirus infections, and consider testing for other infections with overlapping clinical manifestations.