Acquired cytomegalovirus infection of breast milk in infancy.

A cross-sectional study was conducted to examine the rate of cytomegalovirus (CMV) shedding through breast feeding and the rate of acquired infection by the infants. Among the 104 seropositive breast-feeding mothers, CMV was recovered in the milk in 19 cases, with a milk shedding rate of 18.3%. Isolation of CMV from the urine of the infants of the 188 seropositive mothers found 36 positive cases. Of the 36 cases, 15 of 19 fed on CMV-positive milk were infected through breast-feeding, with an infection rate of 78.9%; 11 of the 85 fed on CMV-negative milk were infected, the infection rate being 12.9%; and 10 (11.9%) of 84 fed on cow's milk were infected. These demonstrate that the rate of infection in infants fed on virus-positive milk was significantly higher than those fed on virus-negative milk or cow's milk (P less than 0.005).