Zika virus is a mosquito-borne virus transmitted by Aedes mosquitoes and is known to circulate in Africa, the Americas, Asia and the Pacific. Infection with Zika virus usually results in mild illness and symptoms may include fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache.

Although Zika virus disease is generally mild, increased cases of congenital microcephaly and Guillain-Barré syndrome have been observed in recent outbreaks in the Americas and the Pacific and a growing body of evidence points towards a causative role for Zika virus in these neurological disorders.

Current widespread transmission of the virus and detection of the virus in breast milk from two mothers with confirmed Zika virus infection has also raised questions as to whether transmission can occur during breastfeeding, a practice essential to infant and young child survival and development. However, there are currently no documented reports of Zika virus being transmitted to infants through breastfeeding and in countries with ongoing transmission of Zika virus, no adverse neurological outcomes have been reported to date in infants with postnatally acquired Zika virus disease.

Based on the available evidence, which suggests that the benefits of breastfeeding for the infant and mother outweigh any potential risk of Zika virus transmission through breast milk, WHO has issued interim guidance on breastfeeding in the context of Zika virus.