Breast milk-acquired cytomegalovirus infection in very low birth weight infants

Perinatal transmission of human cytomegalovirus (HCMV) infection in very low birth weight (VLBW) premature infants can lead to serious clinical symptoms and it has ben increasingly recognized that breast milk is the most frequent route of transmission. Breast milk is considered ideal food for newborns because of its nutritional value and anti-infectious components, but it can also be vehicle for viral and bacterial infection. The majority of HCMV seropositive mothers shed the virus into their breast milk and can transmit infection to their offspring. Perinatally acquired infections in full-term neonates are usually asymptomatic without sequelae due to protective maternal HCMV-specific antibodies received during pregnancy. In contrast, VLBW preterm infants are at risk of symptomatic infection with neutropaenia, thrombocytopaenia, sepsis-like syndrome and, less frequently, pneumonia and enteric infection. Postnatally acquired infection seems to spontaneously resolve without altering the clinical outcome. Ganciclovir treatment is restricted to severe symptomatic infections. Preterm infants with a gestational age <30 weeks, or with a birth weight <1000 g, are at greater risk of severe postnatal symptomatic HCMV infection, transmitted via maternal milk. The pasteurization of breast milk entirely eliminates infectivity and prevents virus transmission but alters nutritional and immunological milk properties, and freezing reduces, but does not eradicate, infectivity. Most authors encourage fresh maternal breastfeeding because its beneficial effects outweigh the risk of a transient infection, sequelae-free. Nevertheless, an individual decision based on the condition of health of the infant is important.