Infectious-mononucleosis-like Disease with Negative Heterophil Agglutination Test. Clinical Features in Relation to Epstein-Barr Virus and Cytomegalovirus Antibodies

Antibodies to the Epstein-Barr virus (EBV) were determined in 44 cases of infectious-mono-nucleosislike disease with negative heterophil-agglutination test. In 25 of the 44 eases, cytomegalovirus (CMV) was excluded as the etiologic agent; tonsillitis and/or enlargement of the lymph nodes were present in 23 of these cases and absent in two. High anti-EBV titers found in 8 patients were indicative of a current or recent infection; 12 had titers that were compatible with either current or past infection; 5 had low titers or no antibodies, a finding that presumably excludes the presence of a current infection. In 19 of the 44 cases, all without tonsillitis or lymphadenitis, the disease was caused by CMV; the anti-EBV titer was high in 2, moderate in 13, and low in 4. In one of these 19 cases, the anti-EBV titer after mononucleosis was found to be the same as in serum obtained before the illness. There was no correlation between the titers of antibodies to EBV and CMV. In heterophil-antibody-negative mononucleosis, EBV and CMV seem to be the principal etiologic agents, but a proportion of such cases are caused by other, as yet unidentified, agents.