Aetiological studies of diarrhoeal diseases in infants and young children in Iran.

The aetiology of diarrhoeal diseases was investigated among 715 patients admitted to four Children's Hospitals in Tehran, during February 1986 to March 1987, and also among 443 patients attending the central Out-Patient Clinic in Sanandaj, State of Kordestan, during October 1986. Enteropathogenic Escherichia coli (EPEC) were the most common pathogens found in both areas. Almost 26.7% of the patients in Tehran and 20.1% of the patients in Sanandaj were infected with EPEC. Enterotoxigenic E. coli (ETEC) were the next most frequent groups found (17.1% both in Tehran and Sanandaj), with heat-stable enterotoxin (ST)-producing strains being dominant. Of 122 ETEC strains isolated in Tehran, 94 (77%) strains produced ST, 15 (12.3%) strains produced heat-labile enterotoxin (LT) and 13 (10.7%) strains produced both LT and ST. Almost the same pattern of toxigenicity was observed among ETEC strains isolated in Sanadaj. Of the 76 ETEC strains isolated in this area, 70 (92.1%) strains were ST producers, followed by those producing both LT and ST (five strains) and LT only (one strain). One strain of enteroinvasive E. coli (EIEC) was also isolated from a patient in Tehran. The rates of salmonella and shigella isolation were 8.8 and 5.7% in Tehran and 3.8 and 4% in Sanandaj respectively. Enterohaemorrhagic E. coli, Vibrio cholerae and V. parahemolyticus were not isolated but a mixture of two or more pathogens was found in 59 patients (8.2%) in Tehran and in 20 patients (4.5%) in Sanandaj. These findings suggest that diarrhoegenic E. coli are the most important cause of diarrhoeal diseases in infants and young children in these areas in Iran.