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CDC report finds 6 percent of Zika-infected pregnancies result in fetal anomalies; agency issues travel advisory for Brownsville, Texas

About 6 percent of pregnant women infected with the Zika virus had a fetus or delivered an infant with an anomaly related to the virus, according to a new report from the Centers for Disease Control and Prevention (CDC), the Washington Post's "To Your Health" reports (Sun [1], "To Your Health," Washington Post, 12/14).


The Zika virus is not easily diagnosed, and it does not have a cure or vaccine. The virus is most commonly transmitted by a bite from an infected mosquito, but it can also be spread through sexual activity.

Researchers have linked Zika infection during pregnancy to congenital Zika syndrome, which includes microcephaly, a sometimes fatal anomaly in which a fetus develops an abnormally small head and brain; decreased brain tissue with a distinct pattern of calcium deposits that suggest brain damage; damage to the back of the eye; limited range of motion in the joints; and excessive muscle tone that restricts movement shortly after delivery.

Zika has been found in 60 counties since the outbreak was identified last year in Brazil (Women's Health Policy Report, 12/12). As of Dec. 7, there have been 4,575 reported cases of Zika infection in the United States and 33,712 cases in U.S. territories (CDC Zika case counts, accessed 12/15).

Report details

According to "To Your Health," the report is the first data analysis submitted to the U.S. Zika pregnancy registry. The registry was established in January as a collaborative effort between CDC and state and local health agencies in most U.S. states and territories to monitor Zika infection among pregnant women.

Specifically, the report assessed outcomes among 442 Zika-infected women, across several U.S. states, who completed their pregnancies between Jan. 15 and Sept. 22 ("To Your Health," Washington Post, 12/14). The study did not include women from Puerto Rico (Stobbe, AP/Sacramento Bee, 12/14).

All of the women included in the report contracted the infection while traveling or through sex with an infected partner. The countries where women were infected included Barbados, Belize, Brazil, Colombia, Dominican Republic, El Salvador, Guatemala, Haiti, Honduras, Mexico, Marshall Islands and Venezuela.

Key findings

According to the report, 6 percent of the pregnancies, or 26 in total, resulted in at least one Zika-related fetal anomaly, most of which were microcephaly with brain anomalies. However, researchers found that the percentage of pregnancies involving Zika-related anomalies increased to 11 percent when they focused on women infected during the first trimester of pregnancy (Sun [1], "To Your Health," Washington Post, 12/14).

Of the 26 affected fetuses or infants, 21 were born with fetal anomalies and five pregnancies ended in stillbirth, miscarriage or abortion (AP/Sacramento Bee, 12/14). Overall, 18 of the Zika-affected infants had microcephaly -- accounting for 4 percent of all completed pregnancies. According to "To Your Health," that rate of microcephaly is "substantially higher" than the overall rate in the United States, which is usually about 0.07 percent of births (Sun, "To Your Health," Washington Post, 12/14).

For the first time, the report also found that there was no significant difference in the rate of fetal anomalies among infected women who displayed Zika symptoms themselves and those who did not (Steenhuysen, Reuters, 12/14).


The researchers said the findings demonstrate the rate of Zika-related fetal anomalies among infected pregnant women in the United States is comparable to the rate of such anomalies among infected pregnant women in Brazil. Tom Frieden, director of CDC, in an interview Wednesday said, "This basically puts to rest speculation that Brazil was different in some way."

Separately, citing the wide variety of countries where women were infected by the virus, Margaret Honein, head of the CDC branch focused on fetal anomalies and report author, said, "The commonality here is Zika, not one geographic location."

Honein added that the study results align with recent findings in Brazil showing that about 10 percent of women exposed to Zika in the first trimester and who completed their pregnancies delivered infants with microcephaly (Sun [1], "To Your Health," Washington Post, 12/14). Overall, in the Brazil study, researchers found that 42 percent of 117 infants born to Zika-infected women had "grossly abnormal" clinical or brain imaging results (AP/Sacramento Bee, 12/14).

According to the researchers, the findings underscore public health advisories cautioning pregnant women from travelling to areas experiencing an outbreak of the virus. The researchers also reiterated the importance of testing all pregnant women with possible Zika exposure, as well as all infants born to infected women, as Zika-related anomalies sometimes do not present immediately at birth (Sun [1], "To Your Health," Washington Post, 12/14).

CDC issues travel advisory for Brownsville, Texas

In related news, CDC on Wednesday advised pregnant women to avoid traveling to Brownsville, Texas, because of an outbreak of the Zika virus, the New York Times reports.

Brownsville has reported at least five cases of Zika transmitted via local mosquitos (McNeil, New York Times, 12/14). Texas officials reported an initial case of locally acquired Zika in November, followed by four additional locally acquired cases earlier this month. None of the identified patients are pregnant (Women's Health Policy Report, 12/12).

Advisory details

CDC's advisory applies to pregnant women, reproductive-age women and their sexual partners who have resided in or traveled to the Brownsville region on or after Oct. 29 (Sun [2], "To Your Health," Washington Post, 12/14).

In the advisory, CDC said women living in or visiting Brownsville and the surrounding Cameron County should take all possible measures to avoid mosquito bites and use condoms when having sex for the duration of their pregnancy (New York Times, 12/14). In addition, CDC advised Zika testing for all pregnant women who live in the area, traveled to the area or had sex without a condom with someone who resides in Brownville or traveled in the region on or after Oct. 29 (Sun [2], "To Your Health," Washington Post, 12/14).

The agency also recommended that women and couples in the region who are considering pregnancy "discuss their reproductive life plans with their health care provider," who should tell them about the risks posed by the virus. According to the advisory, women who believe they might have been exposed to the virus should postpone trying to get pregnant for at least eight weeks and men who believe they might have been exposed should wait at least six months before having unprotected sex (New York Times, 12/14).