Box 2. SI- Environmental stress gradient model Susceptible hosts (S) grow logistically and have a density at which birth rate (b) hits zero from competition (K, carrying capacity). As an assumption of relative change, transmission rate (β) and background death (d) are sensitive to environmental stressors (E), βE and dE, respectively. From our meta-analysis results, environmental stress (and pollution) affected survival, regardless of infection status. However, infected hosts (I) reproduce at a smaller rate than susceptible hosts (ρ, relative fecundity of I compared to S) and have increased mortality due to the pathogen (ν). Parameters used in our simulations: b = 0.5, K = 10, β = 0.01, d = 0.01, E = varies (0-1), βE = varies (-8, -4, -2, 0, 2, 4, 8), dE = 2, ρ = 0.25, ν = 0.04.