In December of 2015, Magdalena Sanz Cortes was seeing patients at Texas Children’s Hospital and teaching classes in the ob-gyn department at the Baylor College of Medicine, when she got a call from Barranquilla, Colombia. Miguel Parra Saavedra, a gynecologist in the coastal metropolis, was worried by all the patients coming to his office showing signs of the mysterious Zika virus that had hit Brazil less than a year before. Alarming reports of microcephaly—abnormally small heads and brain damage caused by the Zika virus—were beginning to come out of Colombia’s neighbor to the east.