If you're pregnant, or considering becoming pregnant, you're probably paying close attention to the flood of Zika virus news.
That's smart, experts say: the mosquito-borne virus that has been linked with brain abnormalities in infants will almost certainly hit the United States before a vaccine or treatment is found. This week the World Health Organization warned every country in North, South and Central America except Canada and continental Chile to expect the virus.
That means the best protection is to avoid being bitten by mosquitoes – which is not much comfort for parents-to-be who have recently traveled to countries where the disease is rampant.
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Dr. Laura Riley, president of the Society for Maternal-Fetal Medicine and a specialist in high-risk pregnancies at Massachusetts General Hospital, has fielded many concerned calls from pregnant women who are worried that their baby might have microcephaly (ME), a condition that causes a baby to be born with an extremely small head.
"They're so nervous and frustrated and feeling awful and I wish I could make them feel better," Riley said.
But the only tests available are difficult to interpret, and not widely available, so they're being reserved for pregnant women who have symptoms of Zika. The problem is, 80 percent of people infected with the virus don't have symptoms. In fact, that's why countries like Brazil were blindsided: No one realized the extent of the infections until 3,893 babies were born with ME starting in October, up from less than 150 cases in 2014.
"For all sorts of reasons, it's the worst case scenario," Riley said.
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While fetuses of worried American parents are being monitored by ultrasound, which can detect ME at around 24-27 weeks, some countries such as El Salvador and Colombia are advising women to delay getting pregnant for months or even years. Even in the U.S., it's been suggested that couples consider factoring their risk of Zika in when considering getting pregnant, especially in areas projected to be hardest hit.
Because so little is known about the virus – nothing has been published in scientific journals – the best approach is to assume the U.S. is vulnerable, said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine.
It could be that Zika follows the pattern of other mosquito-borne viruses that didn't take hold in the United States, but that's far from a certainty – and if the U.S. isn't prepared, it would be a "disaster nine months later," Hotez said.
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"The other factor to consider is poverty," Hotez said, and that doesn't mean the U.S. is immune. "People don't recognize the level of extreme poverty in the 5th ward of Houston."
Standing water in discarded tires provides ideal breeding grounds for mosquitoes, and most homes are not protected by screens.
So far, about a dozen Americans who traveled to infected countries have tested positive for Zika. While they could potentially spread the virus by being bitten by mosquitoes in the United States and those mosquitoes biting others, the areas considered most at risk are places where the type of mosquitoes most efficient at transmitting the disease live, in the southeast of the country. [CDC map]
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In Texas, where the Aedes mosquito thrives, and 20 other states, abortions are illegal by the time ME could be detected on an ultrasound. And summer is fewer than nine months away, although some say it's too soon to delay pregnancies in the U.S., especially since transmission is suspected to occur during the first trimester of pregnancy. Still, those uncertainties are what keep the phones ringing in OB/GYN offices.
"We're advising women who are concerned to do an ultrasound check every three to four weeks, because we don't know the natural history of the disease," Riley said. "That's what most obstetricians would be interested in knowing: if you're exposed in the third trimester, for example, what is the likelihood a baby would have ME? Does the virus have any effect that late in pregnancy?"
With the potential to affect everything from socioeconomics to the U.S. presidential election, Hotez said, it's difficult to take a wait-and-see approach.
"Hopefully by the time it's more widespread in the U.S. we have more information and hopefully we'll learn more about how to best utilize the tests, and learn a lot more about the natural history of the disease and the power to prevent it," Riley said.