In this paper we claim that a combination of an agent-based model and a SIG-based environmental model can act as a "virtual laboratory" for epidemiology. Following the needs expressed by epidemiologists studying micro-scale dynamics of avian influenza in Vietnam, and after a review of the epidemiological models proposed so far, we present our model, built on top of the GAMA platform, and explain how it can be adapted to the epidemiologists¿ requirements. One notable contribution of this work is to treat the environment, together with the social structure and the animals¿ behaviors, as a first-class citizen in the model, allowing epidemiologists to consider heterogeneous micro and macro factors in their exploration of the causes of the epidemic.