British Escherichia coli O157 in Cattle Study (BECS): to determine the prevalence of E. coli O157 in herds with cattle destined for the food chain

Abstract

Escherichia coli O157 are zoonotic bacteria for which cattle are an important reservoir. Prevalence estimates for E. coli O157 in British cattle for human consumption are over 10 years old. A new baseline is needed to inform current human health risk. The British E. coli O157 in Cattle Study (BECS) ran between September 2014 and November 2015 on 270 farms across Scotland and England & Wales. This is the first study to be conducted contemporaneously across Great Britain, thus enabling comparison between Scotland and England & Wales. Herd-level prevalence estimates for E. coli O157 did not differ significantly for Scotland (0·236, 95% CI 0·166-0·325) and England & Wales (0·213, 95% CI 0·156-0·283) (P = 0·65). The majority of isolates were verocytotoxin positive. A higher proportion of samples from Scotland were in the super-shedder category, though there was no difference between the surveys in the likelihood of a positive farm having at least one super-shedder sample. E. coli O157 continues to be common in British beef cattle, reaffirming public health policy that contact with cattle and their environments is a potential infection source.

Keywords: Escherichia coli (E. coli) O157; Bovine; epidemiology; estimating disease prevalence.

Fig. 1.

Mean seasonal prevalence estimates (solid triangles Scotland, solid dots England & Wales) including 95% CI (horizontal bars) for the herd-level and pat-level prevalence of Escherichia coli O157 in Scotland (blue) and in England & Wales (red) for farms sampled in Scotland (n = 110) and England & Wales (n = 160) between September 2014 and November 2015. Integer values beside each dot indicate the total number of farms or pats, as appropriate, sampled within each survey/season.