Using PCR techniques Shiga toxin-producing strains of Escherichia coli were isolated from the faeces of 45 out of 101 healthy sheep. These strains were serotyped and found to include O5:H-, O91:H- and O163:H19, which had previously been reported as being associated with human disease including haemolytic uraemic syndrome.Utilisant la technique P.C.R. des souches d'Escherichia coli produisant des toxines Shiga ont ete isolees a partir de faeces de mouton en bonne sante dans 45 cas sur 101. Ces souches ont ete isolees comme etant O5:H-, O91:H- et O163:H19. Ces serotypes ont precedemment ete decrits comme etant associes a des maladies humaines y compris le syndrome uraemique haemolytique.