The Zika virus, a mosquito-borne disease suspected of causing unusual birth defects and possibly other health issues, is expected to spread to parts of Latin America and the Caribbean.

The Zika virus was first discovered in monkeys in the Zika forest in Uganda in 1947. It is native mainly to tropical Africa, with outbreaks in Southeast Asia and the Pacific Islands. It showed up in Brazil last year and has since been seen in many Latin American countries and Caribbean islands.

According to the World Health Organization, Zika is rapidly spreading in the Americas because it is new to the region, and people aren’t immune to it. The Aedes aegypti mosquito, which carries the virus, is just about everywhere - including along southern United States. Canada and Chile are the only places without this mosquito.