Concurrent infectious mononucleosis and measles: a potentially life-threatening association sharing underlying immunodeficiency.

We report lethal interstitial pneumonia in an 18-year-old young man with measles infection following recent infectious mononucleosis. We speculate that the documented T cell immune impairment caused by the concurrent Epstein-Barr and measles viral infections (as expressed by a proportionately low CD4+ lymphocyte count) was responsible for the complicated clinical course and unfavorable outcome.