Epidemiological investigation of recurrent outbreaks of haemolytic uraemic syndrome caused by Shiga toxin-producing Escherichia coli serotype O55:H7 in England, 2014-2018

Abstract

Recurrent outbreaks of haemolytic uraemic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC) serotype O55:H7 occurred in England between 2014 and 2018. We reviewed the epidemiological evidence to identify potential source(s) and transmission routes of the pathogen, and to assess the on-going risk to public health. Over the 5-year period, there were 43 confirmed and three probable cases of STEC O55:H7. The median age of cases was 4 years old (range 6 months to 69 years old) and over half of all cases were female (28/46, 61%). There were 36/46 (78.3%) symptomatic cases, and over half of all cases developed HUS (25/46, 54%), including two fatal cases. No common food or environmental exposures were identified, although the majority of cases lived in rural or semi-rural environments and reported contact with both wild and domestic animals. This investigation informed policy on the clinical and public health management of HUS caused by STEC other than serotype O157:H7 (non-O157 STEC) in England, including comprehensive testing of all household contacts and household pets and more widespread use of polymerase chain reaction assays for the rapid diagnosis of STEC-HUS.

Keywords: Food-borne zoonoses; Shiga-like toxin-producing E. coli; gastrointestinal infections; outbreaks; public health emerging infections.

Fig. 1.

Epidemiological curve showing cases of STEC O55:H7 in England by month and year of onset, 2014–2018.

Fig. 2.

Age/sex pyramid of all cases of STEC O55:H7 in England, 2014–2018.

Fig. 3.

Map showing the geographical distribution of cases.

Fig. 4.

Phylogenetic tree showing the relationship between STEC O55:H7 linked to the recurrent outbreaks of in England between 2014 and 2018. All isolates were from human cases unless otherwise stated. Each sample is labelled by location, year of isolation and short read accession number. ROI – Republic of Ireland. *designated as a sporadic case.