As Mandal et al. (2011) review, there is a rough hierarchy of models for vector-borne disease, focusing on malaria. These range from Ross (1911) through Macdonald (1957) to Anderson and May (1991), who present, respectively, two-, three-, and four-dimensional models. Macdonald and Anderson-May extend the Ross model to include latent periods in both human and vector. Further extensions explore the role of immune competence, superinfection, pathogen evolution, host and mosquito behavior, migration, population age structure, spatial dynamics, environmental factors, and so on, all largely variations on the Ross and Macdonald theme (Reiner et al. 2013). Yang (2000) studies a model containing ten differential equations.