The epidemiology, microbiology and clinical impact of Shiga toxin-producing Escherichia coli in England, 2009-2012

Abstract

Between 1 January 2009 and 31 December 2012 in England, a total of 3717 cases were reported with evidence of Shiga toxin-producing E. coli (STEC) infection, and the crude incidence of STEC infection was 1·80/100 000 person-years. Incidence was highest in children aged 1-4 years (7·63/100 000 person-years). Females had a higher incidence of STEC than males [rate ratio (RR) 1·24, P < 0·001], and white ethnic groups had a higher incidence than non-white ethnic groups (RR 1·43, P < 0·001). Progression to haemolytic uraemic syndrome (HUS) was more frequent in females and children. Non-O157 STEC strains were associated with higher hospitalization and HUS rates than O157 STEC strains. In STEC O157 cases, phage type (PT) 21/28, predominantly indigenously acquired, was also associated with more severe disease than other PTs, as were strains encoding stx2 genes. Incidence of STEC was over four times higher in people residing in rural areas than urban areas (RR 4·39, P < 0·001). Exposure to livestock and/or their faeces was reported twice as often in cases living in rural areas than urban areas (P < 0·001). Environmental/animal contact remains an important risk factor for STEC transmission and is a significant driver in the burden of sporadic STEC infection. The most commonly detected STEC serogroup in England was O157. However, a bias in testing methods results in an unquantifiable under-ascertainment of non-O157 STEC infections. Implementation of PCR-based diagnostic methods designed to detect all STEC, to address this diagnostic deficit, is therefore important.

Keywords: Escherichia coli; foodborne zoonoses; gastrointestinal infections; infectious disease epidemiology; zoonotic foodborne diseases.

Fig. 1.

Flowchart of all cases reported to the national enhanced surveillance scheme for STEC (NESSS), 2009–2012. GBRU, Gastrointestinal Bacteria Reference Unit; STEC, Shiga toxin-producing E. coli; ESQ, enhanced surveillance questionnaire. * Thirty-four cases were attributed to both travel and outbreaks. † It was not possible to determine an epidemiological case definition with the information available.

Fig. 2.

No. confirmed and probable cases of Shiga toxin-producing E. coli (STEC) and incidence of STEC/100 000 person-years by age group and gender reported to the national enhanced surveillance scheme for STEC (NESSS), 2009–2012.

Fig. 3.

Age and sex distributions for cases of (a) Shiga toxin-producing E. coli (STEC), (b) campylobacteriosis, and (c) salmonellosis and reported to national surveillance systems in England, 2009–2012.

Fig. 4.

Age and sex distribution for symptomatic confirmed and probable Shiga toxin-producing E. coli (STEC) cases in England reporting (a) bloody diarrhoea, (b) hospitalization and (c) progression to HUS, 2009–2012.

Fig. 5.

(a) Rurality and (b) geographical distribution of Shiga toxin-producing E. coli (STEC) incidence in England, 2009–2012.