META-ANALYSIS
We conducted a systematic literature search and meta-analysis to evaluate the impacts of three broad types of environmental stressors on disease dynamics. First, we confirmed that pathogen exposure in laboratory studies typically negatively affected host fitness. We then proceeded with our main meta-analyses focused on two specific questions: Q1) were stressor fitness effects more severe for infected vs. uninfected hosts?, and Q2) was infectivity more susceptible to environmental stress than host fitness traits? To address these questions with data from primary studies, we used infection intensity and prevalence as proxies for infectivity and survivorship and fecundity as proxies of host fitness.