A complex system perspective on the emergence and spread of infectious diseases: Integrating economic and ecological aspects

- Epidemics reflect the dynamics of complex ecological-economic systems.
- Disease emergence stems from the expansion of the macroeconomic system.
- Disease spread depends also on human behaviour.
- Economics/psychology can be used to integrate behaviour into disease spread models.
- Innovative hierarchical approaches are needed to model disease emergence and spread.

The emergence and spread of infectious diseases reflect the interaction of ecological and economic factors within an adaptive complex system. We review studies that address the role of economic factors in the emergence/spread of infectious diseases and identify three broad themes. First, the process of macro-economic growth leads to environmental encroaching, which is related to the emergence of infectious diseases. Second, there are mutually reinforcing processes associated with the emergence/spread of infectious diseases. For example, diseases can cause significant economic damages, which in turn may create the conditions for further spread. In addition, the existence of a mutually reinforcing relationship between global trade and macroeconomic growth amplifies the emergence/spread of infectious diseases. Third, microeconomic approaches to infectious disease point to the adaptivity of human behaviour, which simultaneously shapes the course of epidemics and responds to it. Most of the applied research has focused on the first two aspects, and to a lesser extent on the third aspect. In this respect, there is a lack of empirical research aimed at characterising the behavioural component following a disease outbreak. Future research should seek to fill this gap and develop hierarchical econometric models capable of integrating both macro and micro-economic processes into disease ecology.