In California two babies are born with the severe birth defect microcephaly after their mothers contracted the Zika virus, authorities said.
The California Department of Public Health (CDPH) did not reveal where the mothers were from but said they were infected this year in a country where it is endemic.
‘In pregnant women Zika can cause permanent damage to the developing fetus, including microcephaly, a condition in which the infant's skull and brain are unusually small.’
"While mosquitoes that can carry the virus have been found in 12 California counties, there is no evidence these mosquitoes are transmitting Zika in the state at this time," the CDPH said.
The state has reported 114 cases of travel-associated Zika infections in 22 California counties as of July 29.
"This is a sobering reminder for Californians that Zika can cause serious harm to a developing fetus," said CDPH director Karen Smith, urging pregnant women to avoid areas with known Zika transmission.
There is no cure for the virus, which causes no symptoms in four out of five cases. People who do feel sick from it may experience a rash, joint pain or eye infection.
Scientists are scrambling to find a way to contain the pathogen, which is spreading in 50 countries and territories, mainly in Latin America, the Caribbean and the US state of Florida.
Three experimental Zika vaccines being developed in the United States have worked well in monkeys, according to research published in the journal Science
Two other candidate DNA vaccines are in human trial in the United States and Canada.