Update on the Transmission of Zika Virus Through Breast Milk and Breastfeeding: A Systematic Review of the Evidence

Abstract

We systematically searched regional and international databases and screened 1658 non-duplicate records describing women with suspected or confirmed ZIKV infection, intending to breastfeed or give breast milk to an infant to examine the potential of mother-to-child transmission of Zika virus (ZIKV) through breast milk or breastfeeding-related practices. Fourteen studies met our inclusion criteria and inform this analysis. These studies reported on 97 mother–children pairs who provided breast milk for ZIKV assessment. Seventeen breast milk samples from different women were found positive for ZIKV via RT-PCR, and ZIKV replication was found in cell cultures from five out of seven breast milk samples from different women. Only three out of six infants who had ZIKV infection were breastfed, no evidence of clinical complications was found to be associated with ZIKV RNA in breast milk. This review updates our previous report by including 12 new articles, in which we found no evidence of ZIKV mother-to-child transmission through breast milk intake or breastfeeding. As the certainty of the present evidence is low, additional studies are still warranted to determine if ZIKV can be transmitted through breastfeeding.

Pregnancy and viral infections: Mechanisms of fetal damage, diagnosis and prevention of neonatal adverse outcomes from cytomegalovirus to SARS-CoV-2 and Zika virus

“…Among exposed fetuses, fetal loss occurred in 14% and severe complications compatible with Congenital Zika Syndrome (CZS) occurred in 21% [ 221 ]. To date, although ZIKV particles have been detected in human milk, breastfeeding has not been confirmed as a transmission route and mothers with possible or confirmed ZIKV infection are recommended to keep breastfeeding their babies [ 223 ]. Mechanisms of fetal damage …”

Excretion of Cell-Free and Cell-Associated Zika Virus into Breast Milk of Infected Dams and Identification of Antiviral Factors

“…Since the 2007 outbreak, it has repeatedly been suggested that ZIKV can be transmitted to newborns through breastfeeding [ 12 ]. However, since several case reports described no transmission of ZIKV from infected mothers to their newborn [ 26 ], biological factors regulating the efficiency of this route of transmission might exist (viral load, viral form, immunological status, stage of lactation, breast milk composition, etc.). We investigated the role of breast milk and its components in viral transmission using a well-described animal model for ZIKV infection: A129 mice.…”

“…Although cases of probable transmission of ZIKV from infected mothers to breastfed newborns have been reported [ 12 ], other case reports showed a lack of transmission by breastfeeding [ 26 ]. Therefore, biological or genetic factors controlling the transmission should be investigated (viral load, viral form, immunological status, stage of lactation, etc.).…”

Arthropod-Borne Flaviviruses in Pregnancy

“…The primary mode of ZIKV acquisition is through the bite of the Aedes aegypti mosquito [ 16 ], or through vertical transmission from an infected mother. Although the virus has been detected in breast milk of infected mothers, clinical data demonstrating transmission via breast milk to the infant is lacking [ 17 ]. Sexual transmission [ 18 ] and acquisition via solid organ or blood transfusions are well-described [ 19 ].…”