. “The best-case scenario here is that we could either limit local transmission or get ahead of it and contain it as soon as possible,” Amy Pope, the deputy assistant for homeland security for President Barack Obama, said in an interview. “We’re in a posture of knowing that time is precious and collaboration is essential,” CDC Principal Deputy Director Dr. Anne Schuchat said. The World Health Organization estimates Zika could eventually affect as many as 4 million people in the Americas. The species of mosquito that carries Zika probably will begin to emerge in the continental United States in April or May. Obama has asked the U.S. Congress for more than $1.8 billion in emergency funding to fight the virus.