Evidence that Microcephaly Risk is Highest among Pregnant Wo
Colombia has experienced a 4-fold increase overall in microcephaly following the Zika virus outbreak in 2016, according to a study published today in the CDC’s Morbidity and Mortality Weekly Report. This preliminary report on Zika virus disease and microcephaly in Colombia demonstrates that an increase in microcephaly is not specific to Brazil. This finding confirms that countries with Zika virus outbreaks are likely to experience large increases in microcephaly and other Zika-related birth defects. The report also suggests that Zika virus infection in the first months of pregnancy poses the greatest risk of microcephaly.

From January 31 through mid-November 2016, there were 476 cases of microcephaly reported in Colombia; this represents more than a 4-fold increase from the same period in 2015, with a 9-fold increase in July 2016 (the peak month) compared with July 2015. Of the 476 cases with microcephaly, 432 were live-born infants and 44 were pregnancy losses...