EDWIN MICHAEL is currently a Senior Lecturer in infectious disease epidemiology at Imperial College London, UK, with a research focus on modelling the transmission and control of tropical parasitic and infectious diseases. His main interest lies in developing a system dynamics approach to gaining a better understanding of parasite transmission, immunology, genetics and economics, in order to develop integrated mathematical models of pathogen transmission as a tool for aiding the rational design, monitoring and evaluation of large-scale intervention programmes, ranging from vector control, chemotherapy to vaccinations. He has worked extensively in Africa (primarily East Africa), India, Vietnam and Papua New Guinea, particularly over the past decade (in partnership with international (WHO, World Bank) and national institutions), in translating research on disease population biology, spatial dynamics and public health decision-making for developing reliable model-based spatial decision support tools to aid the design, surveillance and evaluation of ecologically resilient and sustainable intervention programmes against parasitic diseases of major public health importance in developing countries. His current interest is in extending this work to developing integrated ecological, economic and social systems approaches for investigating interactions between climate change, ecosystem dynamics and the socio-ecology of disease transmission in vulnerable communities.

ROBERT C. SPEAR is an engineer by training, having received the BS and MS degrees in Engineering Science and Mechanical Engineering, respectively, from the University of California at Berkeley and the PhD degree in Control Engineering from Cambridge University in 1968. After several years in the aerospace industry his interests turned to environmental issues and he returned to Berkeley in 1970 to take up a post-doctoral position in this field in the School of Public Health. He was appointed to a faculty position in 1971 and is now Professor of the Graduate School at Berkeley. His research interests focus on the assessment and quantification of human exposures to toxic and hazardous agents in the environment. His early work concerned the exposure of agricultural workers to pesticides. In more recent years his work has concerned applications of mathematical and statistical techniques in the assessment and control of exposures to both chemical and biological agents. For the past 15 years his work has been increasingly focused on determinants of the prevalence and control of the parasitic disease schistosomiasis in the mountainous regions of Sichuan Province in southwestern China.