Researchers Are Studying Twins for Zika Clues

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Jaqueline Jessica Silva de Oliveira and her twins, Lucas and Laura.
Jaqueline Jessica Silva de Oliveira and her twins, Lucas and Laura.Photo: Nacho Doce / Reuters

Medical experts now agree that the Zika virus in pregnant women is a cause of microcephaly in babies — but not every fetus exposed to the virus will be born with the condition, which is marked by an abnormally small head and developmental problems. Now, Brazilian doctors are hoping that sets of twins where only one child is affected will help them understand why some babies are able avoid the ill effects of Zika.

Jaqueline Jessica Silva de Oliveira, 25, told Reuters that she had Zika symptoms early in her pregnancy and ultrasounds suggested that her daughter would be born with microcephaly while her son would not. Lucas and Laura are now 5 months old and Laura requires treatment from neurologists and physiotherapists.

São Paulo doctors are studying Lucas and Laura alongside four other sets of twins to see if there’s a gene that protects some babies or another characteristic that increases infection risk, like one placenta being permeable to Zika but not the other. (Fraternal twins have their own placentas; identical twins normally share one but can also have their own.) And perhaps the neurons of one baby are more resistant to Zika than the other. They hope to have their results within a year.

For now, the Zika outbreak is concentrated in Central and South America, but the virus can be transmitted through sex. If you or your partner have been to one of the affected countries the U.S. government has advice on how long to wait before trying to get pregnant. And if you’re already pregnant, well, the CDC suggests not visiting these places and not having unprotected sex with a man who has until the baby arrives.