CMV in LBW babies: And the culprit is…

A new study of postnatal cytomegalovirus (CMV) infection in very low-birth-weight (VLBW) babies identifies maternal breast milk as the primary source of transmission and eliminates blood transfusion as a possible transmission route when CMV-seronegative and leukoreduced blood are used.

Although maternal breast milk and blood transfusion are the main conduits for CMV in VLBW babies, the risks attributable to each and the effectiveness of preventive measures haven’t been well-defined. To estimate the risks of CMV transmission in breast milk and transfusions of CMV-seronegative and leukoreduced blood, researchers conducted a prospective birth-cohort study at 3 neonatal intensive care units in Atlanta, Georgia.

They enrolled 539 VLBW infants (1500 g or less at birth) who hadn’t had a blood transfusion and their 462 mothers within 5 days of birth. The mothers underwent serologic testing to determine their CMV status; the babies underwent CMV nucleic acid testing (NAT) for congenital infection at birth and at 5 intervals between birth and 90 days, discharge, or death. Maternal breast milk and blood components given to infants after enrollment were examined for CMV using NAT.

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The seroprevalence of CMV among the mothers was 72.6%. At 12 weeks, a 6.9% incidence of CMV infection was found among the infants, 5 of whom developed symptomatic disease or died. Twenty-seven infected babies had been fed CMV-positive breast milk. A total of 2061 transfusions using CMV-seronegative and leukoreduced blood were administered to 310 infants after enrollment; none was linked to CMV infection.

The researchers conclude that using CMV-seronegative and leukoreduced blood products for transfusions in VLBW infants effectively prevents CMV transmission and that the primary source of CMV infection in infants who receive such transfusions is maternal breast milk. 

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