Protozoa - A taxonomic group of single-celled microorganisms that live in almost every kind of habitat and include some pathogenic parasites of humans and other animals. ⏎
Peptic Ulcer - An open sore that develops on the inner lining of the stomach or upper small intestine.⏎
Reservoir - An organism in which a parasite that is pathogenic for some other organism lives and reproduces without harming its host.⏎