Speculation that the Zika virus carried by infected mosquitoes may cause birth defects ended today as the Centers for Disease Control and Prevention said it is in fact the cause for microcephaly and other fetal brain defects in the children of women who have been infected while pregnant.
The CDC and other health organizations have been studying the possible link of this mosquito borne virus and these debilitating and often fatal birth defects since the Zika outbreak hit the Western Hemisphere. It was for this reason that a travel warning was issued in January telling pregnant women to avoid travel to the affected areas.
It has been through these studies, one of which has now been published in the New England Journal of Medicine, that the CDC authors of the study offered evidence that established the link between Zika virus and microcephaly and other fetal brain defects.
“This study marks a turning point in the Zika outbreak. It is now clear that the virus causes microcephaly,” Tom Frieden, M.D., M.P.H., director of the CDC said today. “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. 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.”
Since this first warning was issued by the CDC which covered 13 countries and regions, it has expanded to include over 40 locations where the virus is now endemic. In the warning, women who are pregnant were told they should delay travel and that women visiting the regions should avoid becoming pregnant until after returning and being sure they had not been infected.
Added to the concern of pregnant women traveling to the areas where they could be exposed to the disease by an infected mosquito, it has been found that the illness can also be transmitted to pregnant women by an infected male partner.
In a number of cases, pregnant women who have not traveled to the areas where Zika is active have become infected by male partners who had been in the regions and were infected. In most of the cases, the males who passed the virus had yet to show symptoms of Zika when the transmission occurred.
Zika virus can take 7-10 days to show symptoms and during this time the males could still pass Zika to a female partner. There is also concern that the virus can remain active in male sperm for an unknown period of time after the illness appears to have ended.
With this in mind, the CDC has issued warnings that males who have traveled to the areas where Zika is active use a condom with female sexual partners until there is no chance that they are unknowingly infected.
Though the report cited today by Dr. Frieden does not show a definitive link to Zika and the birth defects, the evidence is compelling enough and the scientific methods used to determine this link strong enough to, in the word of Dr. Frieden, “support the author’s conclusions.”
It was also noted that though that there is the concern for birth defects ranging from miscarriage and microcephaly to other effects to the brain, there is no hard determining factor as to which pregnant women will pass the virus to the fetus if they become infected. In the ongoing studies of pregnant women who have become infected, many continue on with a normal pregnancy, delivering a healthy child unaffected by the virus.
In a further statement from the CDC today, the agency made it clear that all travel warnings stand and all recommended precautions should be followed.
“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.”
More on the Zika virus can be found at the CDC Zika information pages.
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