Sandy Cairncross is Professor of Environmental Health at the London School of Hygiene and Tropical Medicine. He has worked as a water and sanitation engineer for the Government of Mozambique, helped to set-up Guinea worm eradication programmes in West Africa with UNICEF and WHO, and is technical director of WELL, a resource centre providing technical advice on water and environmental health to the UK Department for International Development (DFID) and other agencies. He is also an editor of Tropical Medicine & International Health.