Zika virus—the infectious agent linked to a dramatic rise in the incidence of neurological defects in newborns in Brazil—is spreading at an alarming rate in the Americas, according to a statement issued January 28, 2016, by the director-general of the World Health Organization, Margaret Chan. According to WHO experts, the mosquito-borne Zika virus could infect 3–4 million people in the Americas in 2016. In response to rising levels of concern, Chan elected to convene an emergency committee, which declared Zika virus a global health emergency, officially known as a Public Health Emergency of International Concern, on February 1, 2016. The last such declaration was made in August 2014, following escalation of an Ebola outbreak in West Africa.
The emergency committee met just days after the U.S. Centers for Disease Control and Prevention issued a travel alert for people planning to visit affected countries in the Americas. The alert was aimed particularly at pregnant women because of a link between maternal Zika virus infection and a congenital defect known as microcephaly (an abnormally small head) in newborns. Alarm over the link caused health officials in Colombia, Ecuador, El Salvador, and Jamaica to caution women against pregnancy and to recommend that they wait to become pregnant until more is known about the connection between Zika virus and neurological complications in newborns.