Invasive Amebiasis at an Institution for the Mentally Retarded in Shizuoka Prefecture

Amebiasis caused by Entamoeba histolytica at an institution for mentally retarded in Shizuoka Prefecture is reported. Five of the 50 patients showed E. histolytica cysts in their stools and 4 were positive serologically. The polymerase chain reaction and restriction fragment length polymorphism revealed that the isolates were pathogenic-type E. histolytica. Epidemiological analysis revealed that the amebic infection was caused by the abnormal behavior of mentally retarded patients. Administration of diloxanide furoate and metronidazole for cyst-carriers eliminated cysts from the stool and lowered the antibody titer.