An international team, led by researchers from the Max Planck Institute for the Science of Human History (MPI-SHH), Harvard University and the Mexican National Institute of Anthropology and History (INAH), has used ancient DNA and a new data processing program to identify the possible cause of a colonial-era epidemic in Mexico. Many large-scale epidemics spread through the New World during the 16th century but their biological causes are difficult to determine based on symptoms described in contemporaneous historical accounts. In this study, published in Nature Ecology and Evolution, scientists made use of new methods in ancient DNA research to identify Salmonella enterica Paratyphi C, a pathogen that causes enteric fever, in the skeletons of victims of the 1545-1550 cocoliztli epidemic in Mexico.