Zika (flavivirus), Maternal Zika Virus Infection

Flaviviruses are mainly transmitted by the bite of Aedes mosquitoes (Ae. aegypti and Ae. albopictus or Tiger mosquito) from infected reservoirs that are mostly humans but may also be various animals. The viral infection is asymptomatic in 75% of cases. Only one out of four infected persons generally develop benign symptoms with few complications in adults and children and even infants, with rare admission of patients. ^{(Red Book 2021-24 p.114).}

It has been documented sporadically transmission by sexual intercourse ^{(Musso 2015, Foy 2011)} and vertically from the mother to the child, transplacental and perinatal (AAP 2018 p894). Also of concern is a possible transmission by blood transfusion. ^{(Musso 2014)}

Two infants had positive test for the virus, presumably after perinatal transmission, one remained asymptomatic and the other one with mild symptoms that doubtfully were due to the virus. Both, as well as their mothers evolved favorably. ^{(Besnard 2014)}

Four infants breastfed by mothers with Zika infection (viral RNA in breast milk from one of them) did not become infected with Zika. ^{(Cavalcanti 2017)}

Zika virus RNA has been detected in breast milk from two mothers with confirmed Zika virus infection, but no replicative virus was identified in cell culture ^{(WHO 2016, Besnard, 2014)}. Transmission of the infection through breastfeeding has not been documented. ^{(Red Book 2021-24 p.114, Runge 2019, WHO 2016, CDC 2016)}

Breast milk (colostrum, transitional milk, and mature milk) has antiviral activity against Zika virus, making it difficult for flavivirus to bind to cells. ^{(Francese 2020)}

Since the health benefits of breastfeeding from breastfeeding are considered greater than the unproven potential risk of transmission, experts, expert committees and the World Health Organization recommend that mothers with possible or confirmed infection or exposure to Zika virus continue to breastfeed, even in endemic areas. ^{(Red Book 2021-24 p.114, Mann 2018, WHO 2016, CDC 2016).}