The ecological basis for disease dates at least as far back as 400B.C.E., to Hippocrates’s On Airs, Waters, and Place. As Wilson (1995) notes, our understanding and therefore control of diseases would be inadequate without an ‘ecological’ perspective on the life cycles of parasitic micro-organisms and the associated infectious diseases. Smith et al (1999, p583) contend, ‘many of the critical health problems in the world today cannot be solved without major improvement in environmental quality’.