Sources of Escherichia coli O157 and experiences over the past 15 years in Sheffield, UK

Abstract

SUMMARY In the first documented outbreak of HC caused by Escherichia coli O157, which occurred in the North‐west USA in 1982, there was a strong association between infection and prior consumption of ground beef from a chain of fast food restaurants. Foods of bovine origin, including beef, milk and dairy products, have since been implicated in many outbreaks of infection world‐wide. Investigations during the course of outbreaks, or at random, have shown that cattle are a major reservoir of E. coli O157. E. coli O157 was isolated from cattle at slaughter in Sheffield in 1987, this being the first isolation from cattle in the UK. Following a cluster of cases in May/June 1992, an abattoir study showed the organism to be present in 4% of cattle at slaughter and on up to a third of carcasses from rectal swab‐positive animals. E. coli O157 was isolated from a food source (unpasteurized milk), for the first time in the UK, in Sheffield in May 1993. During surveillance in 1995–6, E. coli O157 was isolated from 157% of cattle, with a monthly prevalence which varied from 5 to 37%. E. coli O157 was also isolated from 22% of sheep. During surveillance in 1996, E. coli O157 was isolated from 59% of samples of lamb products and from 15% of samples of beef products, despite the prevalence in cattle being much higher than in sheep. Work is in progress to try to explain this higher prevalence in lamb products. During 1997 in Sheffield, the only cases of E. coli O157 for which a confirmed source was established were associated with direct animal contact on farm visits. During on‐farm investigations of these cases, E. coli O157 was isolated from faecal samples from adult cattle, calves, three different breeds of sheep, two different breeds of pigs, goats and a pony.

Transmission and control of Escherichia coli O157:H7 — A review

“…As well, geographic location also seems to influence prevalence. For example, the prevalence of E. coli O157:H7 in cattle is higher in the northwest United States and in northern England (Sheffield), than in other areas (Chapman 2000).…”

“…Within the United States, outbreaks are more common in the northern states than in the southern states (Griffin and Tauxe 1991;Slutsker et al 1997;Nataro and Kaper 1998;Chapman 2000). In Canada, reports of E. coli O157:H7 infection have been more frequent in the western provinces than in the east (Griffin and Tauxe 1991;Nataro and Kaper 1998).…”

“…Human infections associated with E. coli O157:H7 appear to be more common during the summer months, with the majority of cases occurring during the months of May through September (Pai et al 1988;Ostroff et al 1989;Waters et al 1994;Boyce et al 1995;Slutsker et al 1997;Coia 1998;Mead and Griffin 1998;Chapman 2000). Ostroff et al (1989) suggested that the increased shedding of E. coli O157:H7 by cattle during summer months may contribute to a similar seasonal pattern of E. coli O157:H7-associated foodborne illness in humans.…”

Effectiveness of simulated interventions in reducing the estimated prevalence ofE. coliO157:H7 in lactating cows in dairy herds

“…Escherichia coli O157:H7 (VTEC O157 in this paper) is one of hundreds of strains of the bacterium E. coli that is found regularly in the faeces of healthy cattle [2,5,21]. It can be transmitted to humans through years, thrombotic thrombocytopenic purpura (TTP) in elderly people, and death [13].…”

Risk of Escherichia coli O157:H7 infection linked to the consumption of beef

“…Cattle act as the main reservoir of E. coli O157:H7 (Bach et al, 2002) while intermittently and seasonally shed the organism in faeces (Chapman, 2000). The majority of the human E. coli O157:H7 cases were due to food and water contaminated with cattle faecal matter (Gyles, 2007).…”