David Mabey is Professor of Communicable Diseases at the London School of Hygiene and Tropical Medicine. He has made and continues to make, a major contribution to tropical medicine in the developing world. Whilst undertaking his first clinical posting overseas in The Gambia, he identified Sexually Transmitted Diseases, in particular chlamydia infection, as a major but neglected cause of serious illness in Africa. His interest in Sexually Transmitted Diseases led naturally to involvement in the African HIV epidemic and he played a key role in the study in Mwanza, Tanzania, that demonstrated definitively that prevention of Sexually Transmitted Diseases can reduce rates of HIV transmission, a trial that has had major impacts on HIV control in Africa and elsewhere.