Zika Virus Linked to Eye Damage

Zika virus, the mosquito-borne illness linked to a rise in babies born with brain damage in Brazil, may be responsible for newborn eye damage as well.

That’s the finding of a new study published this week in the journal JAMA Ophthalmology. The study, which was conducted in December in Brazil, evaluated 29 infants with microcephaly, an incurable condition linked to Zika virus in which babies are born with unusually small heads.

RELATED: Zika Virus: What to Know if You're Trying to Get Pregnant
RELATED: Zika Virus Symptoms: What Are They?
RELATED: More Than 2100 Pregnant Women Infected with Zika Virus

Twenty-three of the mothers said they had experienced Zika virus signs and symptoms while they were pregnant, including rash, fever, joint pain, headache, and itching, and 18 of them said the symptoms occurred during their first trimester.

Nearly 35 percent of the infants studied had eye abnormalities, but they weren’t necessarily in both eyes. The most common issues were black lesions in the back of the eye, retinal tissue damage, or damage to blood vessels and tissue below the retina.

Researchers say it’s hard to know whether the babies can see or how much they can see at this point, but there is damage.

Zika virus has regularly made headlines since January after nearly 4,000 babies were born in Brazil with microcephaly since October, believed to be caused by the virus. (Brazil reported fewer than 150 cases of microcephaly in 2014.) Zika is spreading throughout South America and Central America and the Caribbean, and the World Health Organization recently predicted that the virus will spread to all but two countries in South America, Central America, and North America (including the United States by late spring or early summer).

Because of the virus’s link with severe birth defects, officials in Brazil, Colombia, El Salvador, Ecuador, and Jamaica are urging women to delay having children.

While the eye damage link is new, William Schaffner, MD, an infectious-disease specialist and professor at the Vanderbilt University School of Medicine, tells Yahoo Health that he isn’t shocked by it. “It would appear that the Zika virus, once it gets through the placenta, can get to the child and then it seems to have an attraction to the brain and to related structures,” he says. That includes the eye, which comes from the brain during embryologic development. From there, he explains, the virus gets into the brain, causing inflammation and tissue destruction.

But why might one eye be affected and not the other? And why might some babies avoid eye damage altogether? Schaffner says it depends on where the Zika virus affected the developing child — it often doesn’t affect all areas equally. “The Zika virus localizes, causing inflammation and tissue damage,” he explains. “That will result in how much damage occurs and exactly where the damage is.”

However, board-certified infectious-disease expert Amesh A. Adalja, MD, an assistant professor at the University of Pittsburgh Medical Center, tells Yahoo Health that there is a lot we still don’t know about Zika. “It’s unclear what trajectory Zika takes and why at this point,” he says. “It could have to do with the time of infection, for example.”

With all the news about potential harm to newborns, many are wondering whether Zika may cause more than just a fever, rash, and joint pain in adults. Should adults be worried about eye damage too from Zika infection? Schaffner says there is no indication of this, given what we know about the virus.

The only more serious potential complication in adults that has been detected so far is Guillain-Barre syndrome, a condition in which the immune system attacks the nerves that can cause temporary paralysis. “That’s pretty rare, though,” Schaffner says. “So far, there’s no evidence that the Zika virus causes permanent damage in adults — to the brain, eyes, or any other structure.”

RELATED: Zika virus declared a global health emergency

Despite concerns for adults, Adalja stresses that Zika is a “fairly benign disease for the vast majority of people.”

Schaffner says it’s important for Americans to be aware of Zika and up to date on news of the virus, but to avoid panicking. “Previously, we’ve been able to contain dengue virus and chikungunya [which are also spread via mosquitoes],” he says. “We will be able to contain this.”