GL16

Leprosy, one of the oldest recorded diseases in human history, is still prevalent in Asia, Africa and South America with over 200,000 cases every year, calling for the integration of new perspectives, such as One Health approaches, essential to enable its characterization, prediction, and eradication. A key element to study the evolution and persistence of zoonotic pathogens are animal hosts. Besides its potential, this concept has often not yet been integrated into studies of diseases in the past, although ancient DNA approaches have helped to uncover the evolutionary history and prevalence of diseases in the past. Here we will look into the first insights on medieval red squirrels and their connections to leprosy. We will examine two archaeological sites at Winchester, a medieval English city, well-known for its leprosarium and its connections to fur trade, from which we recovered four medieval Mycobacterium leprae genomes, including one from a red squirrel. In combination with historical and archaeological sources this genetic evidence enabled us to reconstruct new details on the transmission of leprosy between humans and squirrels in medieval times including a yet undetected transmission event. Overall, our study represents the first One Health approach on M. leprae’s past transmissions, which is centered around a medieval animal host strain, and highlights the feasibility of such approaches to understand the disease’s zoonotic past and current potential.