CDC concludes Zika causes microcephaly and other birth defects

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Media Statement

 

Embargoed until 5 PM, EDT

Wednesday, April 13, 2016

                                                                                                                                                   

Contact: CDC Media Relations

404-639-3286                                                 

 

CDC concludes Zika causes microcephaly and other birth defects

 

Scientists at the Centers for Disease Control and Prevention (CDC) have concluded, after careful review of existing evidence, that Zika virus is a cause of microcephaly and other severe fetal brain defects. In the report published in the New England Journal of Medicine, the CDC authors describe a rigorous weighing of evidence using established scientific criteria.

“This study marks a turning point in the Zika outbreak.  It is now clear that the virus causes microcephaly.  We are also launching further studies to determine whether children who have microcephaly born to mothers infected by the Zika virus is the tip of the iceberg of what we could see in damaging effects on the brain and other developmental problems,” said Tom Frieden, M.D., M.P.H., director of the CDC. “We’ve now confirmed what mounting evidence has suggested, affirming our early guidance to pregnant women and their partners to take steps to avoid Zika infection and to health care professionals who are talking to patients every day. We are working to do everything possible to protect the American public.”  

Background

The report notes that no single piece of evidence provides conclusive proof that Zika virus infection is a cause of microcephaly and other fetal brain defects. Rather, increasing evidence from a number of recently published studies and a careful evaluation using established scientific criteria supports the authors’ conclusions. 

 

The finding that Zika virus infection can cause microcephaly and other severe fetal brain defects means that a woman who is infected with Zika during pregnancy has an increased risk of having a baby with these health problems. It does not mean, however, that all women who have Zika virus infection during pregnancy will have babies with problems. As has been seen during the current Zika outbreak, some infected women have delivered babies that appear to be healthy.

Establishing this causal relationship between Zika and fetal brain defects is an important step in driving additional prevention efforts, focusing research activities, and reinforcing the need for direct communication about the risks of Zika. While one important question about causality has been answered, many questions remain. Answering these will be the focus of ongoing research to help improve prevention efforts, which ultimately may help reduce the effects of Zika virus infection during pregnancy.

At this time, CDC is not changing its current guidance as a result of this finding. Pregnant women should continue to avoid travel to areas where Zika is actively spreading. If a pregnant woman travels to or lives in an area with active Zika virus transmission, she should talk with her healthcare provider and strictly follow steps to prevent mosquito bites and to prevent sexual transmission of Zika virus. We also continue to encourage women and their partners in areas with active Zika transmission to engage in pregnancy planning and counseling with their health care providers so that they know the risks and the ways to mitigate them.  

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CDC Declares Zika–Microcephaly Link Solid

The U.S. health agency says it is important for pregnant women to take safe sex precautions and avoid mosquito bites 

• By Dina Fine Maron on April 13, 2016

 

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A baby born with microcephaly is held by his mother as they wait to see a doctor at Oswaldo Cruz Hospital on February 1, 2016 in Recife, Brazil. For illustration purposes only.
Photo by Diego Herculano/Brazil Photo Press/LatinContent/Getty Images

The Zika virus is causally linked to microcephaly, the birth defect that leads to abnormally small head size in infants, the U.S. Centers for Disease Control and Prevention declared Wednesday in The New England Journal of Medicine. The agency said it has not found any definitive new evidence but has weighed the accumulating data connecting the two conditions and concluded that it was solid enough to call causative.

The CDC pointed to compelling evidence from Brazil that highlights a suspicious temporal relationship between pregnant mothers becoming infected with the virus and their babies being born with microcephaly or other serious brain abnormalities. Researchers from the agency also weighed the biological plausibility of the connection, evaluating studiesthat found the virus in the brain tissue of affected fetuses and infants.

Another deciding factor for them was the presence of microcephaly and other brain abnormalities in fetuses or infants who had presumably encountered the virus in utero—conditions that are otherwise relatively rare in the general population.

Although the agency had already issued numerous travel alerts advising pregnant women to stay away from areas with Zika transmission, until now the link between the mosquito-borne virus and and various birth defects had only been considered strong —not definitive. Stating the connection definitively, the CDC staff wrote, “might lead to improved understanding of and adherence to public health recommendations.”

The CDC is not issuing any new health recommendations. Instead, it reiterated its advice that pregnant women should take steps to avoid getting bit by mosquitoes. Because Zika can also be sexually transmitted, the agency says couples should use condoms for at least six months after a male partner’s Zika symptoms arise. There is no current evidence that women can transmit the virus via sexual contact.

For more on Zika, see Scientific American’s Special Report.

http://www.scientificamerican.com/article/cdc-declares-zika-microcephaly-link-solid/

 

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Zika Virus and Birth Defects — Reviewing the Evidence for Causality

Sonja A. Rasmussen, M.D., Denise J. Jamieson, M.D., M.P.H., Margaret A. Honein, Ph.D., M.P.H., and Lyle R. Petersen, M.D., M.P.H.

April 13, 2016DOI: 10.1056/NEJMsr1604338

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http://www.nejm.org/doi/full/10.1056/NEJMsr1604338?query=featured_home

 

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Zika Virus Confirmed as Cause of Rare Microcephaly Birth Defect, CDC Says

• By GILLIAN MOHNEY
• JULIE BARZILAY
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Apr 13, 2016, 5:00 PM ET

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Paulo Whitaker/Reuters

WATCH Zika Virus May Cause Paralysis

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The Zika virus has been confirmed to cause a rare birth defect called microcephaly and other severe problems of the brain, according to a new report from the U.S. Centers for Disease Control and Prevention.

Health officials across the globe have suspected for months a link between the virus and the birth defect, characterized by an abnormally small head and brain. Officials said today the evidence is overwhelming that exposure to virus in utero causes the birth defect.

CDC Director Dr. Tom Frieden called the news a "turning point" in a fight against the virus that has continued to spread throughout the Americas.

“It is now clear that the virus causes microcephaly,” Frieden said. “We’ve now confirmed what mounting evidence has suggested, affirming our early guidance to pregnant women and their partners to take steps to avoid Zika infection and to health care professionals who are talking to patients every day. We are working to do everything possible to protect the American public.”

 

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The CDC is launching new studies to see if other birth defects are connected to the mosquito-borne virus, Frieden said, calling the link "unprecedented" and pointing out there has never been a mosquito-borne virus that causes birth defects in humans. An increase of the birth defect was first detected in Brazil last September months after a large outbreak of the Zika virus.

"We believe microcephaly will be a part of a range of birth defects that may affect women infected at a particular time or at any time during pregnancy," Frieden told reporters.

The findings were published today in the New England Journal of Medicine by CDC researchers who did a thorough review of the available scientific evidence linking the Zika virus and the birth defect.

Dr. Sonja Rasmussen, lead author and director for the Study Division of Public Health Information and Dissemination at the CDC, told reporters today that scientists found a consistent pattern of defects in infants exposed to the virus in utero. Additionally, she said the virus had been found in brain tissue from deceased infants with microcephaly.

Despite the advances that researchers have made in recent months, Rasmussen said “many questions remain,” including how often birth defects occur in fetuses that are exposed to the virus and if a pregnant woman is more at risk during specific stages of pregnancy.

"Not all babies born to mothers who are infected with Zika virus during pregnancy will have problems," Rasmussen said. "We need to learn to answer this question -- if a woman is infected during pregnancy, how often will her fetus have birth defects or other problems?"

The CDC is also investigating if the virus is linked to an increased likelihood of developingGuillain-Barre syndrome, an immunological reaction that can result in temporarily paralysis in adults.

The CDC is not currently changing its recommendations regarding pregnant women or women who may become pregnant. Currently, the CDC advises pregnant women to avoid areas where Zika virus is being transmitted from mosquitoes to people. The agency is also advising men who travel to an area with active Zika transmission and who have a pregnant partner to abstain from sexual activity or use barrier contraception for the duration of the pregnancy.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical School, said the study is a culmination of months of work and shows the threat to public health.

"It brings together the various lines of evidence that in the end provide a very convincing conclusion that the outbreak of microcephaly that we’re seeing Brazil ... is indeed associated with Zika virus, causally," Schaffner said.

http://abcnews.go.com/Health/zika-virus-confirmed-rare-microcephaly-birth-defect-cdc/story?id=38370364