By Nsikan Akpan

A third of the world’s population is at risk of catching the Zika virus, according to a new study led by scientists at Oxford University in England.

The study does not guarantee that this number of people will actually contract the mosquito-borne virus, which was causally linked last week to microcephaly and other birth defects. Instead, the researchers combine climate data, mosquito prevalence and the socioeconomic makeup of each region to chart the likelihood of the disease getting a foothold in a particular location. In three maps published today in the journal eLife, the team charts the past, present and future of this mosquito-borne virus.

“Our findings that a global area inhabited by over 2.7 billion people is highly suitable for transmission of Zika virus…emphasize why the World Health Organization has declared the current outbreak a Public Health Emergency of International Concern,” epidemiologist and study co-author David Pigott from Seattle’s Institute for Health Metrics and Evaluation said in a statement.

Check out the map and article on pbs.org