CDC ships Zika test for pregnant women; Puerto Rico at risk

The government is shipping Zika virus tests for pregnant women to health departments around the country, but warning there could be temporary shortages, as travelers try to tell if they returned with an infection that could put a developing baby at risk.

Health officials don't expect widespread transmission of the mosquito-borne virus in the continental United States, but said Thursday that Puerto Rico is especially vulnerable. They asked for emergency funding from Congress to battle an outbreak that is quickly spreading through Latin America.

"We may see rapid spread through the island and we need to respond urgently," Dr. Tom Frieden, director of the Centers for Disease Control and Prevention, told a Senate appropriations subcommittee.

The Zika virus is suspected of causing a rare but potentially devastating birth defect, an abnormally small head, which can indicate underlying brain damage. Brazil has reported an apparent increase in cases of that defect, called microcephaly, as Zika exploded in that country, although scientists haven't definitively proven the link.

"With each passing day the evidence that Zika is causally related gets stronger," Frieden said. "Even in this week, the data that's come out makes it look very much like this is a virus that's what we call neurotropic—it targets the nerve cells."

His agency last month found the Zika virus in the brain tissue of two dead newborns from Brazil and in placentas from two miscarriages. On Wednesday, European researchers caring for a woman who returned there from Brazil reported a post-abortion autopsy that found the virus in her fetus' severely damaged brain—one a fraction of the proper size and lacking the usual crinkly folds.

If someone is actively infected, the CDC has a test that diagnoses Zika fairly well. But most people experience no symptoms or very mild one, and the antibody test used to tell afterward if they were infected isn't very accurate. It might reflect prior infection with related viruses instead.

The CDC is urging pregnant women or those trying to become pregnant not to travel to Zika-affected areas. But if they already did, the CDC is telling doctors to test the women for Zika between two weeks and 12 weeks after they return. Those thought to have been infected then could undergo ultrasound scans to monitor fetal development.

Frieden said the agency has shipped 62,000 of those Zika tests for pregnant women to health departments and is working on more but "there may be a period of weeks or a couple of months where there aren't enough tests for the women who want to have them done."

How long after Zika exposure is it safe to get pregnant? Asked by lawmakers, Frieden responded, "If this behaves as other viruses behave, there would be no risk to the next pregnancy after some period of a month or so, but we don't know that for sure."

The Obama administration has asked Congress for $1.8 billion in emergency funding to fight Zika at home and abroad, including mosquito eradication, study of the microcephaly link and developing a vaccine. "We are stretched," Frieden said, telling lawmakers the money is needed fast, within weeks.

Asked if health officials couldn't instead use unspent money that Congress allocated for Ebola in West Africa, Frieden said those remaining dollars are committed to ensuring the remnants of that outbreak are stamped out.

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