More than 270 pregnant women in the U.S. are infected with the Zika virus and are at risk of their babies being born with birth defects, federal health officials announced Friday.
The Centers for Disease Control and Prevention updated the way it reports Zika-affected pregnancies. The goal: to get a better grip on the true risk of a woman having a baby with a birth defect after a Zika infection.
The CDC said the new numbers show 279 women tested positive for the virus. This includes 157 women in the 50 states and Washington, D.C., plus 122 in Puerto Rico, the U.S. Virgin Islands and other U.S. territories.
So far, fewer than a dozen have had an "adverse event," such as a miscarriage or evidence that the fetus has a birth defect, CDC officials said.
"These new numbers reflect a broader group of pregnant women — pregnant women who have any laboratory evidence of possible Zika virus infection, and whether or not they recalled symptoms — compared with numbers previously reported," the CDC said in a statement.
The numbers include women who have already given birth, those who have miscarried and those who may have had abortions because of birth defects.
The CDC has been recommending for months that any woman who's pregnant who thinks she could have been exposed to the virus get tested. This includes women who have traveled to Zika-affected areas, and women whose sexual partners have.
The virus is transmitted mostly by mosquitoes, but it can be sexually transmitted, also.
There's now no doubt Zika causes severe and devastating birth defects.
What has not been clear is whether the fetus of a woman who is infected but never had any symptoms is likely to have a birth defect. So CDC had only reported some of the cases of pregnant women with Zika.
But some studies have suggested that a fetus can be affected even if the mother never knew she had Zika. The virus often doesn't cause symptoms. The CDC is now counting all women who have tested positive, and is reporting those numbers publicly.
Dr. Margaret Honein, who heads CDC's birth defects branch, said new numbers will be reported every Thursday. The count will include women whose test results are a little confusing. Dengue virus is a close relative of Zika and tests often confuse the two viruses.
"Our goal is to track all Zika-affected pregnancies," Honein told reporters during a telephone briefing.
The CDC is encouraging all obstetricians and gynecologists to ask their patients about possible Zika infection and to report it to their state health departments so that CDC can get an accurate picture of just how many pregnant women are affected.
"It is critical for pregnant women to have information on whether or not they are likely to be infected," Honein said.
Having a complete count of Zika-affected pregnancies will give CDC a critical piece of data so researchers there can calculate the risk from Zika. Right now, no one can say what the odds are that a woman infected with Zika will have a baby with birth defects. This is very difficult to calculate, because Zika doesn't cause symptoms in all people it infects, or even in most people it infects.
"This information will help healthcare providers as they counsel pregnant women affected by Zika and is essential for planning at the federal, state, and local levels for clinical, public health, and other services needed to support pregnant women and families affected by Zika," the CDC said in a statement.
The federal government is embroiled in a fight with Congress over paying for the increased surveillance and testing, and in preparing for Zika's arrival in the U.S. More than 500 travelers have carried the virus with them from areas where it's circulating. And once mosquito season really heats up, local U.S. outbreaks are likely, health officials say.
The House and Senate have not agreed on funding, and majorities in neither house want to provide the full $1.9 billion President Barack Obama has asked for.
Congress needs to "get moving," Obama said Friday as he was updated by senior health officials on the Zika epidemic.
"This is not something where we can build a wall to prevent. Mosquitoes don't go through customs," Obama said. "Congress needs to get me a bill."