[In Depth] Evidence grows for Zika virus as pregnancy danger
Since late last year when physicians in Brazil warned that a wave of serious birth defects might be linked to a little-known virus called Zika, researchers have struggled to prove the connection. Some in the media have questioned whether the reported increase in birth defects is real; others, particularly environmental activists, have suggested the virus is an innocent bystander, unfairly blamed for defects caused by chemicals or other factors. With three studies published last week, chances that the virus has been wrongly accused are fading. Two independent groups showed that, at least in the lab, the virus eagerly infects developing brain cells, suggesting a mechanism by which it could cause the most striking of the observed birth defects: microcephaly, in which babies are born with abnormally small heads and brains. A third study, following several dozen pregnant women in Brazil who were infected with the virus, directly links the infection...