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I NF E C T I O U S DIS E A SE Protecting Pregnant Women from Zika Virus Public-health officials are advising pregnant women and those planning a pregnancy to learn about the Zika virus, which is transmitted primarily through mosquito bites, and take precautions to protect themselves and their unborn babies from the disease. The virus raised alarm earlier this year when health officials in Brazil identified a cluster of neurological birth defects in newborns whose mothers contracted Zika virus during pregnancy. The virus is linked to cases of microcephaly, in which a baby’s head is smaller than expected and the brain may not develop properly. “Unfortunately, we don’t yet understand the frequency or full scope of harm to the unborn baby,” says Lydia Lee, MD, PhD, a maternal- fetal medicine specialist. “Scientists in the United States and abroad are intensifying investigations to address the mysteries of the Zika infection, and recommendations are being updated almost daily.” Zika virus has spread throughout Latin America and the Caribbean. Experts have warned that Zika virus will continue to spread, and mosquito-borne illness may reach the United States. However, the biggest risk to U.S. women at the moment appears to be travel to highly affected areas, such as Brazil, says Zachary A. Rubin, MD, medical director of UCLA Clinical Epidemiology and Infection Prevention. There is no vaccine or medication that can prevent Zika virus infection. The Centers for Disease Control and Prevention (CDC) recommends that pregnant women consider postponing travel to areas where the virus is UCLAHEALTH.ORG 1-800-UCLA-MD1 (1-800-825-2631) easily transmitted. Women of child-bearing age who must travel should “strictly follow steps to avoid mosquito bites,” CDC officials say. “There are still a lot of things we don’t know about Zika,” Dr. Rubin says. “But, right now, it’s prudent to follow the CDC’s recommendations and protect oneself from mosquitoes.” The type of mosquito that spreads Zika virus is active both indoors and outside, mostly during the daytime. Women of child-bearing age traveling to affected areas should wear long-sleeved shirts and long pants, use permethrin-treated clothing and gear and stay in screened-in or air-conditioned rooms. Insect repellents containing DEET, picaridin and IR3535 are safe for pregnant women, according to the CDC. Nonpregnant women of reproductive age also should avoid mosquito bites while traveling to affected areas. “If they are traveling for extended periods of time, or if they are sexually active, then they should be careful and take precautions to avoid getting pregnant until more is known about the risks of Zika virus,” Dr. Rubin says. Adds Dr. Lee, “Pregnant women concerned about exposure to the Zika virus should talk to a healthcare provider to assess the need for blood tests and detailed fetal ultrasounds.” Only a few cases of Zika infection have been reported in the United States, mostly in people who traveled to impacted areas and some from sexual contact with an infected person who had returned from South America. For the most part, people here need not be concerned about the virus or about getting a mosquito bite, Dr. Rubin says, because the complications largely seem to be limited to pregnancy. Other mosquito-borne infectious diseases, such as malaria and dengue fever, are also a threat to parts of the United States, and are much more serious. “We do have mosquitoes that can potentially transmit Zika virus, but I don’t think people need to be concerned about it here,” Dr. Rubin says. “Zika virus is a fairly mild illness compared to malaria, tuberculosis or dengue fever; those are infections that cause millions of deaths a year.” U.S. public-health officials are familiar with mosquito-borne disease threats and are prepared to deal with them. “We’ve had small dengue fever outbreaks in South Florida and Texas in the past. But those outbreaks were kept fairly isolated,” Dr. Rubin says. Because the disease associated with Zika virus is mild in the vast majority of people, and the association with microcephaly is not yet well understood, many specialists in infectious diseases are cautious but generally less concerned than they are with some other potential infectious threats, such as influenza, tuberculosis and malaria, he says. In men and nonreproductive-age women, the Zika virus is fairly harmless. About one-in-five people infected become ill with mild symptoms that include fever, rash, joint pain and conjunctivitis (red eyes). A more severe neurologic complication of infection called Guillain-Barre syndrome is possible, but very rare, Dr. Rubin says. Symptoms typically last about one week.