The aim of this study was to determine the frequency and allele associations of locus of enterocyte effacement encoded esp and tir genes among 181 enteropathogenic Escherichia coli (EPEC) strains (90 diarrhoea-associated and 91 controls) isolated from Peruvian children under 18 months of age. We analysed espA, espB, espD and tir alleles by PCR-RFLP. EPEC strains were isolated with higher frequency from healthy controls (91/424, 21.7 %) than from diarrhoeal samples (90/936, 9.6 %) (P,0.001); 28.9% of diarrhoeal and 17.6% of control samples were typical EPEC (tEPEC). The distribution of espA alleles (alpha, beta, beta2 and gamma) and espD alleles (alpha, beta, gamma and a new variant, espD-N1) between tEPEC and atypical EPEC (aEPEC) was significantly different (P,0.05). espD-alpha was more common among acute episodes (P,0.05). espB typing resulted in five alleles (alpha, beta, gamma and tw...