Cytomégalovirus néonatal et allaitement maternel chez le nouveau-né prématuré. Quelles propositions?

[Review and guidelines on the prevention, diagnosis and treatment of post-natal cytomegalovirus infection]

Postnatal cytomegalovirus (CMV) infection in the newborn can occur from exposure to maternal cervical secretions during birth, ingestion of breast milk, transfusion of blood products or transmission by body fluids of infected people. Breast milk is the main source of infection, given the high rate of CMV-positive mothers excreting CMV in milk. Freezing reduces the risk of CMV transmission by breastfeeding, although it does not eliminate it completely. Pasteurisation prevents such transmission, but it can alter the immunological properties of breast milk. Postnatal CMV infection is usually asymptomatic, as it normally results from viral reactivation in the mother, and the neonate is born with protective antibodies. However, in the very low birth weight premature infant the amount of transferred antibodies is smaller and a symptomatic infection can occur. Symptomatic post-natal CMV infection in the newborn typically causes hepatitis, neutropenia, thrombocytopenia or sepsis-like syndrome. Pneumonitis and enteritis are less common, but very characteristic. Diagnosis is based on urine virus detection at the time of onset of symptoms. Postnatal CMV infection in the newborn generally resolves spontaneously without antiviral treatment. Ganciclovir should be reserved for severe cases. Unlike congenital CMV disease, post-natal CMV infection in the preterm infant does not seem to be associated with hearing loss or abnormal neuro-development in long term follow-up.

Cytomegalovirus transmission to preterm infants during lactation

Breastfeeding has a major impact on HCMV epidemiology. The incidence of postnatal HCMV reactivation during lactation equals the maternal seroprevalence. Infectious virus, viral DNA and RNA can be isolated easily from cell and fat-free milk whey. Early onset of viral DNAlactia and virolactia as well as high viral load in milk whey are maternal risk factors for virus transmission. The dynamics of HCMV reactivation can be described by unimodal kinetics with interindividual variation. Virus reactivation during lactation is a self-limiting local process in the absence of systemic HCMV infection. Preterm infants below 1000g birthweight and a gestational age below 30 weeks may be at high risk of acquiring a symptomatic HCMV infection. Several recent studies described low transmission rates and mostly asymptomatically infected neonates using frozen milk. Despite different freeze-storing procedures, HCMV transmissions occurred, and severe HCMV infections were observed. Few data exist on the long-term outcome of postnatally acquired HCMV infection via breast milk. To substantiate the international debate on the use of native or inactivated milk for feeding of preterm infants, additional data are necessary for better identification of mother-infant-pairs at risk for viral transmission and symptomatic infection early after birth.