Birth defects among virus cases rarer than initially feared

RIO DE JANEIRO – New figures released Wednesday by Brazil’s Health Ministry as part of a probe into the Zika virus have found fewer cases of a rare birth defect than first feared.

Researchers have been looking at 4,180 suspected cases of microcephaly reported since October. On Wednesday, officials said they had done a more intense analysis of more than 700 of those cases, confirming 270 cases and ruling out 462 others.

But what that means is hard to say, according to some experts. It does not answer whether the tropical Zika virus is causing the babies to have unusually small heads. Nor does it really tell us how big the problem is.

“I don’t think we should lower our alarm over the Zika outbreak,” said Paul Roepe, co-director of Georgetown University’s Center for Infectious Diseases.