An abstract in the April 2006 Journal of Food Protection discussed a Spanish study that investigated the presence of E. coli O157:H7 in raw ewe’s milk collected from several cheese factories over a period of one year.

Of all the ewe’s milk samples studied, three were positive for E. coli O157:H7.

The E. coli O157:H7 strains that were positive were then analyzed for the presence of virulent genes. All E. coli O157:H7 isolates were Shiga toxigenic and harbored additional genes related to virulence.

The results demonstrate that raw ewe’s milk used in cheesemaking may be sporadically contaminated with E. coli O157:H7 strains that are potentially pathogenic for humans.