10 cases of Zika virus reported in San Francisco

SACRAMENTO, Calif. (KTVU & AP) -- The California Department of Public Health said Thursday that California now has two cases of babies born with birth defects due to the Zika virus.

One of the affected babies was born in the past six months at Alta Bates Summit Medical Center in Berkeley with severe microcephly, a source told KTVU, and the mother had apparently traveled to Guatemala.

The names and locations of the babies and their mothers were not released because of health privacy guidelines, but health officials say the two mothers are among 21 California women who have tested positive for the Zika virus. A total of 114 Californians have tested positive for the Zika virus. None of the cases involved transmission of the virus within California. There are a total number of 10 Zika cases in the San Francisco area, according to the Department of Public Health. The patients contracted the virus during travel outside the United States. There is no risk to public health in the area, and Zika is not circulating in San Francisco. 

The Zika virus can lead to flu-like symptoms such as fever, rashes, or body aches, but are usually mild. The virus is believed to remain in the blood for about one week. 

The most severe effects are seen in babies born with microcephely, an unusually small head, which makes them prone to seizures, developmental delays and other problems. Doctors are still studying the long-term effects.

"Zika virus can infect the nerve cells early in development and cause damage and so that's what's thought to cause the small heads, the small brains," said Dr. Erica Pan, a deputy health officer with the Alameda County Public Health Department.

The Zika virus is primarily is transmitted through mosquito bites from a particular Aedes aegypti and Aedes albopictus species of mosquitos. Health officials say the risk of mosquito transmission in the Bay Area is low.

"We don't actually have the Aedes aegypti mosquito established here in the Bay Area," said Dr. Pan.

Health officials say the most important thing is for pregnant women to avoid traveling to Zika-infected areas. A map can be found on the CDC website.

Kim Cardoso, a certified nurse-midwife at LifeLong Medical Center, a community health clinic says they are testing all pregnant women who return from affected areas, according to CDC protocols.

"We are actually recommending that women not travel to areas with active transmission if they're pregnant or planning to get pregnant," Cardoso said.

People also should be aware the virus is transmitted not just through mosquitoes but also through sexual partners.

"It is definitely sexually transmitted and we've learned now that it can not only be male-to-female transmitted but female-to-male," Dr. Pan said.

"For men, they're saying use barrier methods for 6 months. For women, potentially for  8 weeks and try not to conceive in 8 weeks after being in a Zika-impacted area," Dr. Pan said, "They've found Zika virus in semen as long as 90 days after symptom onset and we're studying could it be longer than that."

Babies born to Zika-infected mothers will be followed for up to a year. Health officials will check their hearing, vision and development, said Dr. Connie Mitchell, deputy director of the Center for Family Health. 

Nationwide, 13 babies have been born with Zika-related birth defects, according to the federal Centers for Disease Control and Prevention.

The CDC has advised pregnant women not to travel to parts of Latin America and the Caribbean where Zika transmission is active. The virus is usually spread by mosquitoes, but it can also be passed through sex. 

Most people infected with Zika experience mild symptoms such as fever, rash and joint pain. Zika infection during pregnancy can cause babies to be born with unusually small heads, called microcephaly. 

Florida is the only U.S. state so far that has reported homegrown Zika transmission by mosquitoes in a square-mile neighborhood in Miami-Dade County. The CDC has urged expectant mothers to avoid Miami's Wynwood neighborhood, where at least 15 people are believed to have been infected with the Zika virus through mosquito bites. 

KTVU reporter Jana Katsuyama contributed to this report.