The impacts of El Nino Southern Oscillation (ENSO) on human health are multi-factorial and complex. Climate fluctuations have dramatic and diverse effects on human health and societies, which depend on socio-economic development and geographic location. These effects include ecological aspects of the host vector dynamics of parasitic diseases and the dramatic impact on human livelihood imposed by recurrent episodes of drought and flooding, even if they are not limited to these two main aspects. Although significant efforts have been made to understand global climate fluctuation, they require an important additional contribution to make possible the evaluation of worldwide and local effects, and more urgently, to allow predictions of future consequences. An ethical commitment and the global perspective push us, as a scientific community, to impulse inclusive humane policies based on shared expertise already reached. © 2008, Inderscience Publishers.