Transmission of Vero cytotoxin producing Escherichia coli O157 infection from farm animals to humans in Cornwall and west Devon

Abstract

A study of Vero cytotoxin producing Escherichia coli (VTEC) O157 infections in Cornwall and West Devon was conducted to identify associations between human infection and contact with farm animals. In three years from November 1994 to October 1997, 63,000 stool specimens were submitted to four participating microbiology laboratories and screened for E. coli O157. Sixty-nine confirmed cases were interviewed to assess the extent of any direct or indirect contact with farm animals. Nine out of 22 investigations conducted on farms--in which animal rectal swabs, faecal specimens, fore-stream milk samples (first draw-off from teats), and various environmental samples were tested--yielded VTEC O157. In seven incidents one or more isolates from animals were indistinguishable from the isolate(s) from the human case(s) using phenotypic and genotypic subtyping. Cases associated with animal contact included farm visitors, holidaymakers, and members of farming families and farm workers.