Intestinal parasitic infections in an institution for the mentally retarded

Of 550 mentally retarded patients in an Italian institution, 125 (23%) were found to be infected with intestinal parasites. The infections were most f requent in young men, those with severe mental retardation, the chronically institutionalized and those living in older wards. Ninety-four (75.2%) of the parasitised subjects were infected only with protozoa, 25 (20%) only wi th helminths, and six (4.8%) with protozoa and helminths. Entamoeba histoly tica and E. dispar infections were detected, but at low prevalences; in-vit ro culture in Robinson's medium and isoenzyme electrophoresis of the cloned amoebic isolates indicated one infection with E. histolytica (zymodeme XII ) and two infections with E. dispar (zymodemes I and III). All three Entamo eba-positive subjects were asymptomatic cyst-passers. Antibodies to E. hist olytica were detected in seven (1%) of the sera from the 550 patients exami ned; only one of these was a carrier of an E. dispar strain at the time of investigation. The low prevalences of all the parasitic infections and of the amoebic infe ctions in particular (compared with those observed previously in institutio ns for the mentally retarded) reflect relatively good facilities and sanita ry conditions, an adequate number of well trained staff and good control of the more susceptible subjects.