Two Zika infant cases in state.

Mother at Alta Bates was one of 21 pregnantwomen in state who contracted virus abroad

SACRAMENTO — Two infants with Zika virus-related microcephaly — a devastating birth defect — have been born in California, the California Department of Public Health said Thursday.

Late Thursday, KGO-TV cited unidentified sources who told the station that one of the babies was born at Alta Bates Summit Medical Center in Berkeley.

The babies’ mothers were among 21 pregnant women in the state who contracted Zika while in countries where the virus is spreading. The public health department reported that 114 travel-associated Zika virus infections have been reported in 22 California counties from last year through July 29. In addition, there was one case caused by sexual transmission.

Microcephaly, a neurological condition in which a baby’s head and brain is smaller than

normal, may develop in infants born to women who contract the Zika virus during pregnancy. The condition can cause balance problems, developmental delays and seizures.

The public health department will monitor the infants born to mothers diagnosed with the virus for one year, said Karen Smith, the department’s director and the state’s health officer.

“We will be looking for more serious problems with hearing, with vision and with delayed development, and we will be following up on these infants at two, six and 12 months of age in order to see if there are any further developments that we weren’t aware of,” she said.

About 100 infants are born with microcephaly in California every year, Smith said. To protect the privacy of the women infected with the virus, her department did not disclose Thursday morning where the mothers live. The department also did not say when exactly the two mothers gave birth.

One of the two mothers gave birth in California and then returned to her home country with her infant, officials said. Smith did not say whether the latter mother contracted Zika in her country, but Smith said the woman was from a country where mosquitoes were transmitting the virus.

A spokesman for Alta Bates on Thursday night referred inquiries to Alameda County health officials, who did not immediately return calls regarding the KGO-TV report.

Mosquitoes that can carry the Zika virus have been found in 12 California counties — primarily in Southern California, but also in the Central Valley and San Mateo County. Smith said her department has no evidence that they are transmitting the Zika virus in the state.

“The risk of local transmission in California is low but certainly possible,” said Vicki Kramer, chief of the department’s vector-borne diseases section.

There are still many unknowns about the virus, said Mark Kunitomi, a postdoctoral fellow researching Zika at UC San Francisco. He said that the scientific community didn’t begin studying Zika intensely until recently. Many experts are wary of the potential risk for the virus to spread around the country — especially in warmer regions.

“I would predict that we see more cases of local transmission of Zika virus in the southern United States unless we actively prevent it through mosquito control, research and development of effective diagnostics and treatments,” Kunitomi said.

Lenore Pereira, a professor of cell and tissue biology at UCSF’s School of Dentistry, said that it is of utmost importance for travelers diagnosed with Zika to take precautions against mosquitoes to stop the disease’s spread. Those include using bug spray and wearing long sleeves.

In Florida, mosquitoes became infected with Zika after biting a person who contracted the virus abroad. The virus then spread among the mosquito population, which transmitted it to at least 15 people in Florida.

Aides aegypti mosquitoes, which thrive in warm weather and can only survive year-round in subtropical or tropical regions, are spreading the virus in Florida, Kunitomi said.

Lee Riley, a professor of epidemiology and infectious diseases at UC Berkeley’s School of Public Health, said that some Aedes aegypti and another kind of mosquito that can spread Zika — Aedes albopictus — have been detected in California. But, he said, they don’t pose a significant risk here.

“It’s unlikely that we are going to see what we are seeing in Miami,” Riley said.

Pereira said that the current tests for the Zika virus have very “ambiguous” results and are poor at distinguishing between Zika and dengue fever, another mosquito-borne illness that can cause joint and muscle pain and rashes.

“The tests that are out there are still under development,” she said. “It’s a tricky situation: While the test is still being developed, we have a lot of summertime travel.”

To gear up for the possible increase in Zika-carrying mosquitoes in the United States, states like Florida and Texas should be investing more resources into mosquito control and federal aid should be considered as well, said Art Reingold, associate faculty director of UC Berkeley’s Center for Global Health.

“Many states in the southeastern United States spend little or nothing on mosquito abatement programs, while California has a robust and long-standing mosquito abatement program that we fund through property taxes,” Reingold said.

Hopes for significant federal help were dashed last month, when Congress failed to pass a bill that earmarked $1.1 billion to battle the Zika virus.

Kunitomi called the lack of federal action “a tragedy.”