The health problems associated with the Zika virus continue to pile up, and a new report from researchers in Brazil reveals that the virus can also cause hearing loss in babies born to a mother who was infected.

Scientists are still in the early stages of understanding the full breadth of the health problems that are caused by Zika. The virus is proven to cause the birth defect microcephaly, and other recent studies have shown the virus is also responsible for vision problems and other serious brain damage.

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In the new study, published Tuesday in the U.S. Centers for Disease Control and Prevention (CDC)’s Morbidity and Mortality Weekly Report, scientists report that out of 70 kids with Zika-related microcephaly, four had hearing loss that was caused by damage to the inner ear or damage to the nerve that connects the ear to the brain. The hearing loss couldn’t be attributed to any other cause. Based on this, the researchers say hearing loss should be considered another risk factor for Zika.

Other congenital infections are known to cause hearing problems, but this is one of the first times its been documented among children with Zika-related microcephaly. The researchers add that it’s possible some children born with Zika infections but without microcephaly could also be at risk for hearing problems, though this has not yet been determined.

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