The virus is spreading in Brazil and is suspected to be responsible for the birth defect microcephaly, according to an international study published Monday in the Lancet.
A study published earlier this year also showed that Zika can cause microcefasias in infants.
The Zika virus has been detected in blood and urine in at least 12 people in Brazil, and researchers say they have found evidence of Zika in fetal tissue.
Brazil’s health minister has said the country will not accept more than 10,000 Zika cases, and health officials have been under increasing pressure to control the spread of the virus.
The World Health Organization has warned Brazil to restrict travel to and from the country until there is more proof of a link between the Zika infection and microceferias.