If you are healthy, cytomegalovirus (CMV), a common infection found in many people, is rarely a cause for concern and in most cases doesn’t even show symptoms. But for those with weakened immune systems, CMV can cause disease and, in some cases, may even lead to death. Now a new study has identified a potential source of CMV in premature babies, who are among those at highest risk of infection: breast milk.
Breast milk is considered to be the best source of nutrition for all babies, including preemies. However, because of their immature immune systems, premature infants are particularly vulnerable to developing a cytomegalovirus infection — especially when they have very low-birth-weight (VLBW). Despite such weakness, the American Academy of Pediatrics claims the value of breast milk still outweighs the risks of disease from CMV.
To evaluate CMV incidence in preemies, a group of researchers led by Dr. Cassandra Josephson, Emory University School of Medicine, enrolled 462 mothers and 539 VLBW infants in a study conducted at three neonatal intensive care units. After testing the mothers, the researchers found a majority (76.2 percent) had a CMV infection prior to delivery. Next, the researchers tracked incidence of CMV in babies by testing them at birth (to see how many had a congenital infection), and again at five separate intervals between birth and 90 days, discharge, or death. None of the infants, at the time of enrollment in the study, had received a blood transfusion.
What did the researchers find? Of the 539 premature babies, a total of 29 (or 6.9 percent) became infected with CMV and five of these infected babies developed severe disease or died. While 310 of the premature infants had received a total of 2,061 blood transfusions, none of the resulting CMV infections could be linked to transfusion. However, 27 of 28 infections occurred due to infants being fed CMV-infected breast milk.
“We believe our study is the largest evaluation of both blood transfusion and breast-milk sources of postnatal CMV infection in VLBW infants,” Josephson noted. She and her team estimate somewhere between one in five and one in 10 VLBW infants who are fed CMV-positive breast milk will develop CMV infection. While that is a high proportion, then, the majority of babies clearly do not become infected. To prevent breast milk transmission, the authors suggest routine CMV-testing of pregnant mothers; closer surveillance of infants with CMV-positive mothers; and pasteurization of breast milk until the gestational age of 34 weeks.