The Zika virus has been found in 42 countries and territories for the first time since last year, but Brazil is the hardest hit. And what doctors and researchers are finding from Brazil's outbreak is troubling. The mosquito-borne virus has been definitively linked to microcephaly, or children born with abnormally small heads, when a pregnant woman is infected, but "the scale and severity of prenatal damage by the Zika virus are far worse than past birth defects associated with microcephaly," The Wall Street Journal reports.