Two infants have been born in California with Zika-related microcephaly, the state Department of Public Health reported Thursday. In both cases, the mothers contracted the virus while pregnant, after spending time in a country where Zika is spreading.
Department of Public Health Director Dr. Karen Smith emphasized that infants born with birth defects as a result of maternal Zika infection don't pose a risk to public health.
"This is a sobering reminder, however, for Californians that Zika can cause serious harm to a developing fetus," she said.
Smith said both infants were born alive. She said one mother and baby are doing well; the other mother took her infant back to her home country. State officials don't have follow-up information for her, but they are reaching out to authorities in that country, Smith added.
Smith declined to provide more details on the cases, including where the mothers gave birth.
Babies born with microcephaly have abnormally small heads.
State and national health officials are urging pregnant women to avoid travel to areas with known Zika transmission. They say pregnant women who must travel to these areas should prevent mosquito bites and consult a health care provider when they return.
As of July 29, the state health department has confirmed 114 travel-associated Zika virus infections in 22 California counties; 21 of those cases have been in pregnant women. The department updates this information every Friday.
Nationwide, there have been 13 babies born with Zika-related birth defects as of July 21; there have also been six pregnancy losses with birth defects, according to the Centers for Disease Control and Prevention.
People can contract Zika virus through the bite of an infected mosquito. Most never develop symptoms; those who do report fever, rash, joint pain and red eyes. The symptoms last for several days to a week after being bitten. There is currently no vaccine or treatment for Zika.
The mosquitoes that can carry Zika, Aedes aegypti and Aedes albopictus, have been found in 12 California counties, including Los Angeles, Orange, Riverside and San Bernardino, but there is no evidence these mosquitoes are transmitting Zika locally at this time.
Dr. Vicki Kramer, chief of the vector-borne diseases section at the state health department, said the risk of local transmission of Zika virus is "low but certainly possible." For this to occur, a person infected with Zika would need to enter California with the virus still circulating in his or her blood; an Aedes aegypti or Aedes albopictus mosquito would need to bite this person and ten days later, the mosquito would be infectious. It could then spread the disease by biting others.