Quantitative detection of HCMV-DNA in saliva from infants and breast milk on real-time polymerase chain reaction

Background: The role of breast milk in viral transmission has not been fully studied. To determine the effect of breast milk on the establishment of primary human cytomegalovirus (HCMV) infection in term infants, HCMV-DNA was measured in breast milk and infant saliva. Methods: The study population consisted of 48 healthy term infants and their mothers. The copy number of HCMV-DNA in the infants' saliva and mothers' milk was measured on quantitative real-time polymerase chain reaction (PCR). Results: HCMV-DNA was detected in both saliva and breast milk from 21 infant-mother pairs, in milk only from four pairs, in saliva only from 12 pairs, and in neither from 11 pairs. HCMV-DNA was first detected in the saliva of 10 infants at age 4 months, seven infants at 7 months, 13 infants at 10 months, and three infants at 12 months. The viral loads peaked 4-10 months after birth, and thereafter decreased or became negative. The peak copy number and rate of HCMV-DNA detection in saliva were significantly related to peak copy number and rate of detection in the corresponding breast milk. Conclusion: Thus, HCMV passed through breast milk 1-7 months after delivery affects the persistence and level of HCMV-DNA in infant saliva and is the most important route of primary infection.