The World Health Organization says the mosquito-borne Zika virus is "spreading explosively" and could infect up to 4 million people in the Americas.

Officials say the virus, which is linked to a rare birth defect and other illnesses, has spread to 24 countries in Central and South America, Mexico, the Caribbean and Africa.

According to the Centers for Disease Control and Prevention, there are 31 people infected in the United States in 11 different states, plus 20 more in U.S. territories. Those people became infected after traveling to one of the affected areas. One case was discovered in Nassau County.

Nassau University Medical Center CEO Dr. Vic Politi says the county has a very large Central American population. The hospital now has protocol in place to screen pregnant women who come into the emergency room or health clinic. He says expectant mothers who have traveled to an affected area will be seen by an infectious disease specialist.

Health officials in Nassau said the resident who was infected after traveling abroad has made a full recovery. It was discovered that his illness was contracted over the summer and was originally classified as West Nile.