Breastfeeding May Pass Zika Virus to Infants

Zika found in women’s breast milk infected with the virus during the 36th week of pregnancy

newborn with mom

Venezuela researchers have found evidence that mother-to-child transmission of Zika virus through breastfeeding, is possible.

These researchers said the results of genetic testing of Zika virus isolated from a mother’s breast milk and her child’s urine, “strongly suggest” transmission during breastfeeding.

The Zika virus has been identified in breast milk before.

During 2017, researchers reported the Zika virus was found in breast milk of a woman in Brazil infected with the virus during the 36th week of pregnancy. Zika was detected 33 days after onset of signs and symptoms and 9 days after delivery.

In this case, there were no abnormalities reported during fetal assessment or after the birth of the infant.

According to the Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO), Zika infected mothers should breastfeed their infants.

Current evidence suggests that the benefits of breastfeeding outweigh the theoretical risk of Zika virus infection transmission through breast milk.

In the U.S. territories, 5 percent of women who had confirmed Zika virus infection during pregnancy had a baby or fetus with Zika virus-associated birth defects, according to a CDC Morbidity and Mortality Report in June 2017. 

Among the women with confirmed Zika infection during the first trimester, 8 percent or nearly 1 in 12 had a baby or fetus with Zika virus-associated birth defects.

“As these latest findings illustrate, Zika virus poses a serious threat to pregnant women and their babies, regardless of when the infection occurs during the pregnancy,” said CDC Acting Director Anne Schuchat, M.D.

“Women in the U.S. territories and elsewhere who have continued exposure to mosquitoes carrying Zika are at risk of infection. We must remain vigilant and committed to preventing new Zika infections.”

The CDC says the Zika virus can be transmitted from a pregnant woman to her fetus during pregnancy (congenital transmission) or around the time of birth (perinatal transmission).

Congenital or intrauterine transmission of Zika virus occurs when a woman is infected with Zika virus during her pregnancy, but before delivery, and the virus passes to the fetus.

Perinatal transmission of Zika virus occurs when a woman is infected with the Zika virus within approximately 2 weeks of delivery, and the virus passes to the infant at or around the time of delivery. When an infant acquires Zika virus infection perinatally, the infant may develop symptoms such as maculopapular rash, conjunctivitis, arthralgia, and fever. We do not know how often perinatal Zika transmission occurs. The information on perinatal transmission is limited. The spectrum of clinical features that might be observed in infants who acquire Zika virus during the perinatal period is currently unknown.

As of December 19, 2017, a total of 2,364 women in the USA, and 4,690 in the US Territories have been reported to the Zika registry.

These researchers did not disclose any conflicts of interest: Gabriela M Blohm John A Lednicky Marilianna Márquez Sarah K White Julia C LoebCarlos A Pacheco David J Nolan Taylor Paisie Marco SalemiAlfonso J Rodríguez-Morales, J Glenn Morris, Jr Juliet R C PulliamAlberto E Paniz-Mondolfi.