Zika virus causes microcephaly in only 1% of births; most harmful to pregnant women in first trimester

The outbreak of Zika virus, a mosquito-borne disease, first began in Brazil in 2014. It has since spread swiftly throughout 31 countries and territories in the Americas. Then, earlier this year, the World Health Organization declared a public health emergency of international concern after finding a link between Zika and microcephaly, a congenital birth defect. This association, however, had not been quantified, nor the potential risks estimated, until now. To assess the possible dangers, researchers from Institut Pasteur conducted an analysis of data from a past Zika outbreak in French Polynesia, which had been the largest epidemic until the current one took its place. Their analysis concluded the risk of microcephaly is about 1 percent for a mother who becomes infected with Zika virus during the first trimester of pregnancy. Lead author Dr. Simon Cauchemez and his colleagues suggested the risk of microcephaly is greater when mothers are infected during their first...