A medically important genus of amphibious freshwater operculate snails of the family Hydrobiidae (subfamily Hydrobiinae; subclass Prosobranchiata). In Asia, several subspecies of Oncomelania hupensis serve as intermediate hosts of the oriental blood fluke, Schistosoma japonicum.
[onco- + G. melas (melan-), black]
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Examples: glitazone, GI cocktail, etc.