Researchers have found the strongest evidence so far of a possible link between a mosquito-borne virus and a surge of birth defects in Brazil, the U.S. Centers for Disease Control and Prevention said Wednesday.
The health agency said evidence of the dengue-like Zika virus was found in the placentas from two women who miscarried and the brains of two newborns who died. Those who were born had small heads, a rare condition known as microcephaly.
“The evidence is becoming very, very strong of the link between the two,” said Dr. Lyle Petersen, director of mosquito-borne diseases at the CDC.
Finding the virus present in brain tissue is “very significant,”.
Petersen warned that the link is not yet definite and said that a team of CDC investigators is traveling to Brazil in a few weeks to conduct more studies and learn what risks face pregnant women. “It’s possible that there may be some other co-factors involved.”
Zika is spread by the same Aedes mosquito that can carry dengue and chikungunya. There are no known cases of people contracting the virus in the U.S. mainland, though it has been seen in retrning travelers. Puerto Rico reported its first case of Zika two weeks ago, and 13 countries in Latin America have also seen infections.
The virus is related to dengue but until recently was thought to have only mild symptoms. It was first detected in humans in Uganda decades ago, but there had never been reports of links between the virus and brain malformations until recent months.