title: Biological agents.
mesh_terms: D000818:Animals; D003003:Clonorchiasis / Q000150:complications; D016481:Helicobacter Infections / Q000150:complications; D016480:Helicobacter pylori; D006801:Humans; D007239:Infections / Q000150:complications*; D009369:Neoplasms / Q000209:etiology*; D009889:Opisthorchiasis / Q000150:complications; D012553:Schistosomiasis haematobia / Q000150:complications; D014777:Virus Diseases / Q000150:complications