Algal-fungal host-parasite interactions are ubiquitously observed in aquatic ecosystems, which are key driving forces of algal population dynamics and material flows from phytoplankton to higher trophic levels. In this presentation, we would like to first summarize the achievements from two modeling studies. The first model (Miki et al. 2011 Freshwater Biology 56:1173-1183) focuses on the impacts of trophic interactions between fungal zoospore and zooplankton (i.e., mycoloop) on food web dynamics and quantitatively predicts the contribution of mycoloop on zooplankton production. The second model (Frenken et al. 2019 Ecology, https://doi.org/10.1002/ecy.2900) focuses on the role of zooplankton in suppressing fungal parasitism and predicts the “minimum prevalence of infection” to which the zooplankton can suppress the fungal infection rate. Then, we are going to present a new model, which aims to describe heterogeneity of epidemic patterns within a host population. With the proposed model, we derived a novel frequency distribution that belongs to the class of exponentially-weighted Poisson distribution (EWPD). The novel EWPD can better fit to the observed patterns of multiple infections than classical Poisson distribution, suggesting non-random and density-dependent interactions between algal host cells and fungal zoospores.