Ross Dunn is Professor Emeritus of History at San Diego State University, USA, where he taught African, Islamic, and world history. He was the first elected president of the World History Association, and he is a recipient of its Pioneers of World History award.Urmi Engineer Willoughby is an Associate Professor of History at Pitzer College, USA. Her research focuses on histories of disease and medicine from a global and ecological perspective. Her first book, Yellow Fever, Race, and Ecology in Nineteenth-Century New Orleans (2017) was awarded the 2017 Williams Prize for the best book in Louisiana history.