Parasitism is an detrimental interrelationship between 2 organisms; the parasitic organism and its host. Parasitism results in the parasitic organism thriving, while the host organism suffers and degenerates, possibly die of disease from the interaction.
Below is an example article that describes a study of Parasitism and diseases this interrelationship contributes to. "... Th(e) study demonstrate(d) that a specific parasite-derived protein (that) can mimic its human homolog to increase inflammation and cell proliferation, which, in turn, may result in the promotion and progression of prostate cancer. ... "
Association between trichomoniasis and prostate and bladder diseases: a population-based case–control study