In the study, which appeared on September 27 in Nature Communications, scientists analyzed decades of environmental data associated with Lassa virus outbreaks, revealing temperature, rainfall and the presence of pastureland areas as key factors contributing to viral transmission. The researchers projected that areas hospitable to Lassa virus spread may extend from West Africa into Central and East Africa in the next several decades. With this expansion and expected African population growth, the human population living in the areas where the virus should—in theory—be able to circulate may rise by more than 600 million.