Variations in disease patterns are a result of how populations and niches overlap and interact over space and time. Disease ecologists study these interactions to help predict how changes in some component of this population–niche interaction (an ecosystem) will affect disease outcomes. Mathematical modelling is often used to help foster understanding and prediction capabilities.
At their simplest, disease ecological models contain three components: host, pathogens, and environment. The Mass Action Principle establishes that the interaction between infectious and susceptible individuals is a key factor determining the distribution and abundance of an infectious disease.