Rio de Janeiro, Brazil (AFP)—The Zika virus, believed to be linked to the serious birth defect microcephaly, presents a “formidable” challenge that will be hard to stamp out, World Health Organization chief Margaret Chan said Wednesday. “Things could get worse before it gets better,” she said in Rio de Janeiro after a fact-finding mission to Brazil, the epicenter of the global health scare. Chan said part of the challenge in fighting the mosquito-borne virus […]