CMV infection from Mother’s Milk

Capretti MG, Lanari M, Lazzarotto T, et al. Very Low Birth Weight Infants Born to Cytomegalovirus-Seropositive Mothers Fed with Their Mother's Milk: A Prospective Study. J Pediatr (June 2009); 154; 842-848. Full Text | Full-Text PDF (350 KB)

Objective. To assess the risk of post-natal cytomegalovirus (CMV) transmission to very low birth weight (VLBW) infants fed with their mother's fresh milk.

Study design. Prospective, observational study of 80 VLBW infants and their 68 mothers. Infants' urine and their own mother's fresh breast milk were tested for CMV by means of culture tests once a week until discharge. CMV in infected milk and urine were genotyped. The clinical course, laboratory findings, and outcome of infants infected with CMV at 2 years of age are reported.

Results. Fifty-three mothers (78%) were CMV-seropositive at delivery. CMV was detected in the milk of 21 of 53 seropositive mothers (40%), and CMV was in the urine in 9 of 26 infants (35%) fed with CMV-positive milk. The same gN-genotype was found in milk and urine. Three infected infants <28 weeks gestational age (GA) had a mild sepsis-like illness. Five more infants had neutropenia, conjugated hyperbilirubinaemia, or both. Post-natal CMV infection occurred in 1 of 19 infants with a GA<28 weeks who were treated at birth with intravenous immunoglobulin versus 3 of 5 non-treated infants (P < .02). Symptomatic CMV infection was associated with bronchopulmonary dysplasia. No neurosensorial sequelae were found at 2 years of corrected age.

Conclusions. CMV infection via fresh human milk is mild, self-limiting, and without sequelae. Very-low GA and pre-existing chronic diseases are associated with symptomatic infection.

Comments: CMV transmission in human milk is well known, however the risks are poorly defined. Transmission may be limited by freezing or pasteurizing milk. However, such manipulations change the properties of the milk and may limit its benefits. In this study, 35% of the infants fed CMV-positive milk became infected with CMV. Of the 9 preterm infants infected with CMV, 3 had a mild sepsis-like illness (with neutropenia), and 5 others had mild neutropenia and/or direct hyper-bilirubinemia. None of the infected infants had hearing, visual or neurodevelopmental problems at 2 years of age. The authors concluded that CMV transmission from human milk causes a mild and self-limited disease. DB

Editor’s Comment: In this study, 25 of 62 (40%) VLBW infants with CMV sero-positive mothers were given a prophylactic IVIG preparation. This was done in infants < 28 weeks gestation as part of a NICU protocol to prevent nosocomial infection. Only 2 (8%) of the infants who received IVIG developed CMV infection compared with 7 (25%) of the infants who did not receive this preparation (p=0.06). Is IVIG protective against mother’s milk- associated CMV infection? Hmmm. ABK