aedes aegypti
What is the Zika virus?
01:55 - Source: CNN

Story highlights

Doctors should ask pregnant women with symptoms of Zika virus about recent travel history

Testing should be done by local or state health departments, CDC says

80% of individuals with Zika virus infection have no symptoms

CNN  — 

The U.S. Centers for Disease Control and Prevention is recommending pregnant women who have recently traveled to areas where Zika virus is transmitted be screened for the mosquito-borne disease.

This applies to pregnant women who have traveled to Brazil, Colombia, El Salvador, French Guiana, Guatemala, Haiti, Honduras, Martinique, Mexico, Panama, Paraguay, Suriname, Venezuela and Puerto Rico.

Pregnant women with two or more symptoms should undergo a blood test for the virus.

Symptoms include fever, rash, joint pain and red eyes (conjunctivitis). But the CDC estimates 80% of people infected with the virus have no symptoms, which is why pregnant women without symptoms should be given an ultrasound to check their developing fetus for microcephaly or intracranial calcifications. If an abnormality is detected, a follow-up blood test should be performed.

Microcephaly is a neurological disorder that results in babies being born with abnormally small heads, causing severe developmental issues and sometimes death.

Zika virus has been linked to a sharp increase in cases of infant microcephaly in Brazil, which prompted the CDC to issue a travel advisory last week for pregnant women to postpone travel to these areas.

Dr. Denise Jamieson, a medical officer with the CDC division of reproductive medicine and an obstetrician, said prevention is what’s most important. “Pregnant women should be advised that they may not want to travel to areas with ongoing transmission but if they do, they should take measures to avoid mosquito bites,” she said.

There is no treatment for the virus and the only way to prevent it is to reduce the risk of mosquito bites when in these geographic areas.

Only the CDC and a few states are equipped to perform the testing, according to the CDC, which says it will confirm all tests it receives. The test is not perfect, Jamieson said, noting a risk of false positives or even inconclusive results. “We don’t want to recommend everyone be tested and then have a situation where you can’t sort out who is truly positive,” she said. The wait for results can take about a week.

Amniocentesis, in which a needle is used to retrieve a sample of amniotic fluid from the uterus, is recommended as a follow-up in women who have had a blood test result that is positive for Zika virus or who have had an abnormal finding on an ultrasound. Women who have tested negative should consider follow-up ultrasounds for the duration of their pregnancy under the new guidelines.

In cases that are positive, the mother-to-be should talk with her health care provider about options.

Dr. Laura Riley, director of obstetrics and gynecology infectious disease at Massachusetts General Hospital and chair of the American College of Obstetrics and Gynecology immunization expert working group, said when a baby has microcephaly, it’s brain function is unknown and the infant may be very sick, so at the very least, parents would want to have specialists on hand at delivery.

“The really tough thing here is for those who may have been infected nothing can be done. We’re hunting and looking for something we can’t do anything about. There’s no treatment and no prevention, other than just not getting bitten,” said Riley.

Follow CNN Health on Facebook and Twitter

CNN’s Sandee LaMotte contributed to this report