infectious disease pythiosis MESH:D058968 MONDO:1010000 UMLS:C0276912 GARD:0011989 pythium insidiosum infection human pythiosis MEDGEN:124447 icd11.foundation:1571230529 A granulomatous disease caused by the aquatic organism pythium insidiosum occurring rarely in humans. It is classified into three forms: ocular, cutaneous, and arterial.