Contracting the Zika virus during the first trimester of pregnancy may increase the risk of the baby being born with the birth defect microcephaly, and may also increase a woman's chances of miscarrying, federal health officials said Friday.
The Centers for Disease Control and Prevention examined the cases of nine U.S. women who had traveled to Zika-affected regions between August 2015 and January 2016. What doctors found among the nine was "surprising," said Dr. Tom Frieden, CDC director.
- Four of the nine women who got the Zika virus through mosquito bites either had spontaneous miscarriages, or ended their pregnancies once they found out they had Zika or were carrying a fetus with microcephaly. All of those women got the virus between their sixth and 12th week of pregnancy.
- One of the nine had a premature birth and her baby had severe microcephaly. She, too, contracted the virus between her sixth and 12th week of pregnancy.
- Two of the nine women who were infected with the virus in their second trimester had healthy babies.
- Another woman, infected in her third trimester, had a healthy baby.
- Yet another woman is still pregnant, and her pregnancy, so far, is normal, the CDC reported.
Frieden called the situation “unprecedented.”
“We’re not aware of any previous case of a mosquito-borne virus that can cause birth defects,” Frieden said during a press conference Friday on the findings.
CDC laboratories have found Zika virus in the placentas of Brazilian women who've had babies with microcephaly.
In the case of the U.S. women who had first-trimester miscarriages, the virus was also found in the “products of conception,” which were tested by the CDC. Dr. Denise Jamieson, who is part of the CDC’s Zika virus response team, said the “products” could include cells and fluids expelled in a miscarriage.
In addition, the CDC is monitoring 10 more cases of pregnant U.S. women who contracted Zika through travel. Details of their pregnancies were not released. The agency also declined to provide any information about where the 19 women lived. At least four of the nine women cited in the report were in their 30s.
The agency reiterated its advisory that pregnant women avoid all travel to areas with a Zika outbreak.
Epidemiologists are still trying to nail the link between Zika and microcephaly, which causes unusually small heads and neurological disorders in newborns. The virus is also suspected in a rise of Guillain-Barré syndrome, a virus that attacks the nervous system causing severe paralysis and, in some cases, death.
Scientists haven’t figured out whether a Zika infection alone causes the disorders or whether other factors work in concert with the virus. Frieden said, however, it looks increasingly likely that Zika is the cause of microcephaly and that the first trimester of pregnancy “may be a period of higher risk” for women and fetuses.
The CDC has a team of researchers in Brazil, where the virus has exploded, trying to unlock what is still a scientific mystery. Zika has spread throughout the Americas and is growing steadily in Puerto Rico, where “even though the numbers are small, there are considerable interests,” Frieden said of the territory. Puerto Rico has reported just over 100 cases of the virus.
Avoiding Zika, however, may become increasingly difficult, as it is poised to hit the United States once mosquito season starts. The two mosquitoes that carry the virus, the Aedes aegypti and the Aedes albopictus, are considered “the cockroaches of mosquitoes,” said Frieden. They live indoors, breed in the smallest pools of standing water, and are highly active all day, not just at dusk.
There is also increased danger of sexual transmission of Zika, as the CDC is investigating 14 cases where the women's only known exposure to Zika was through sex with men who had traveled to affected areas. Two of those cases are confirmed sexual transmissions, four are probable, six are still under investigation, and two have been ruled out.
Men who have recently returned from Zika-affected areas shouldn’t have unprotected sex with any woman who is pregnant or is trying to get pregnant. Or they should abstain from all forms of unprotected sex if their partner is pregnant. The virus persists in semen after a man recovers from the illness, but researchers don’t know for how long.
These latest results have prompted researchers to re-examine other aspects of the disease. Earlier findings determined four out of five people who contracted Zika have no symptoms. Yet all but one of the nine pregnant women whose pregnancies were monitored by the CDC had at least two symptoms of the virus.
Zika symptoms include fever, rash, joint pain and conjunctivitis.
The CDC also announced Friday that it was sending testing kits to state health departments so those states could do their own testing for the virus instead of having to send samples to CDC laboratories in Colorado.
The diagnostic kits got Emergency Use Authorization from the Food and Drug Administration this week, allowing the CDC to send them to states.
Georgia will get kits in the coming weeks. People who think they’ve contracted the virus would first have to see a primary care doctor. If they meet the threshold for exposure and have had symptoms, the patient’s doctor would still have to get the health department’s approval for official testing. Pregnant women are the priority, officials said. Test results can take weeks.
About the Author
