Epstein-Barr virus shedding in breast milk.

One hundred healthy women already donating to the Children's Hospital Breast Milk bank consented to provide a sample of breast milk for this study. Using a DNA-DNA hybridization dot-blot assay Epstein-Barr virus (EBV) genome (Bam HIW region) was detected in cells shed into breast milk of 46 out of 100 women studied and in 60 out of 132 (46%) of samples donated overall. The prevalence of EBV shedding increased postnatally to a peak of 74% (26/35 positive samples) between 3 and 12 weeks postdelivery. Women delivering prematurely had an initially lower prevalence of shedding with only six out of 30 (20%) positive samples in the first week after delivery, compared to 16 out of 35 (46%) for women delivering at term. Of the 18 women donating more than one sample, 13 showed consistently positive (n = 8) or negative (n = 5) results, and the remaining five had intermittent shedding detected. Only seven out of 42 (17%) breast milk samples studied were EBV-IgG antibody positive, and none showed IgM or IgA-EBV antibodies. Further studies and prospective followup of infants are needed to confirm that breast milk is a significant source for early EBV infection of infants, as indicated by serologic studies.