The Centers for Disease Control has confirmed the Zika virus can cause birth defects. The defect getting the most attention is microcephaly - babies with abnormally small heads and brain damage. However, there may be other complications still to be uncovered.
"What the CDC is saying is that Zika in pregnant women may lead to a number of complications for their unborn children," says Andrew Pavia, MD, an infectious disease specialist with University of Utah Health. "This is the first time a mosquito borne illness has been definitively linked to birth defects."
Researchers with the CDC carefully reviewed all of the pieces of evidence that linked Zika virus infection during pregnancy to microcephaly, including studies linking the number of infections, timing of infections, type of birth defects, alternate explanations, and experimental evidence using brain cells in the laboratory.
"The researchers also examined the amniotic fluid of the babies with microcephaly," says Pavia. "In many cases the virus was present." Based on the total weight of the evidence, CDC researchers concluded that they can now say there is a definite link between Zika and microcephaly.
The images of newborns with microcephaly may only be only the most obvious and tragic of birth defects associated with Zika. Doctors have suggested a name for the other possible complications in children of mothers who contracted Zika during pregnancy: Zika virus congenital syndrome. Doctors say even in babies born without microcephaly the brain may have been affected by Zika. "We will have to watch for years to come to see the full impact," says Pavia. "Brain damage that happens prenatally can present itself in different ways throughout the lifespan."
CDC officials say they hope by confirming the link people will start taking Zika virus seriously, and take the necessary precautions. These include avoiding travel to areas where the virus is present if pregnant or considering conceiving. "If a woman cannot avoid travel to one of these areas or if she lives in one of these areas the safest course avoid getting pregnant," says Pavia. "This can be done easily with safe, effective, and reversible modern contraception methods. Unfortunately, these are not as available as they should be to women in some places in the U.S. and elsewhere."
People are also being told to take precautions against mosquito bites - including using mosquito repellant. This is especially important as some groups have tried to promote rumors that it is the repellants - and not the mosquitos they work to repel - that are causing the birth defects. "There is absolutely no evidence to link mosquito repellant use and birth defects," says Pavia. "Hopefully the CDC announcement will put these ideas to rest and encourage people to protect themselves."
Much more research needs to be done into the full impacts of Zika, and why this outbreak in particular is causing birth defects - more than a half century after the virus was first identified. "It could be that the virus mutated just enough to cause these complications, or they could have been missed in earlier years" says Pavia. "There are many questions that need to be answered and much more research is needed."