Dengue is a major international public health concern that impacts one-third of the world’s population. There are four serotypes of the dengue virus (DENV). Infection with one serotype affords life-long immunity to that serotype but only temporary cross immunity (CI) to other serotypes. The risk of lethal complications is elevated upon re-infection, possibly because of the effect of antibody-dependent enhancement (ADE). In this paper we propose a system dynamics model that captures both host and vector populations, latency, and four dengue serotypes. This model allows one to study both CI and ADE. Modeling the
vector adds complexity, but we consider this to be important because combating the mosquito vector may be the most practical intervention in the absence of an effective vaccine. Our results support the need to model the vector population and ADE to explain the observed epidemiological data.