Dr. Erin Staples from the United States' Centers for Disease Control and Prevention speaks before members of Brazil's Health Ministry and the Paraiba state's health secretariat in Joao Pessoa, Brazil, Monday, Feb. 22, 2016. A 16-member team of the U.S. Centers for Disease Control and Prevention is starting work on a "case-control" study aimed at determining whether the Zika virus really does cause babies to be born with the devastating birth defect microcephaly, as Brazilian researchers strongly suspect.