MICROBIOLOGY


public health, making it one of the most important foodborne pathogens. Some of the more notable outbreaks include: n The 1993 outbreak was linked to undercooked hamburgers at the Jack in the Box fast-food chain in the US resulted in 732 cases from 73 restaurants across four states. This outbreak mainly affected children, with 55 patients developing HUS. Four children died and 178 were left with permanent injuries including kidney and brain damage.16


n The largest outbreak to date occurred in Sakai City, Japan, in 1996 linked to the O157:H7 strain and was associated with white radish sprouts. It affected over 8,000 school children, with 106 developing HUS. Three of these died.16


n The largest European outbreak to date was identified in central Scotland in 1996 with 501 people becoming ill after consuming meat from a single source. 279 confirmed cases were recorded and resulted in 20 deaths, 17 directly associated with infection.16


Within the UK, STEC O157:H7 has been responsible for around 600 cases each year, associated with a variety of causes including foodborne contamination, raw milk consumption, petting farm exposure and community associated exposure. As well as these frequent sporadic cases, there have been several significant outbreaks within the UK, some of which are listed in Table 1. n The 1996 outbreak as described above in Lanarkshire, Scotland is the largest to date and has led to an increased awareness and understanding of foodborne contamination and thereby enhancing food safety standards.


n In September 2005, South Wales experienced a major outbreak, primarily affecting schoolchildren. A total of 157 cases were identified and resulted in one death. The outbreak was traced to contaminated cooked meats supplied by a local butcher, who was found to have breached food safety regulations. This incident led to a public inquiry directed by Professor Hugh Pennington and resulted in reforms to food hygiene practice.17


n Between August and September 2009, an outbreak occurred among visitors to Godstone Farm in Surrey. 93 individuals, mostly children under ten, were affected and 17 developed HUS. Investigations implicated a petting barn as the source, where contact with infected animals led


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to transmission. The farm temporarily closed, and the event underscored the need for stringent hygiene measures in petting zoos and farms, as reported in the subsequent 252-page Griffin report on the incident, published in June 2010.18


n From May to July 2016, the UK faced a large E. coli O157 outbreak with 165 reported cases. The majority of those affected were adult females, with 66 individuals requiring hospitalisation resulting in two adult deaths. The outbreak was characterised by multiple small clusters linked to catering and residential care premises.19


This event


highlighted the importance of food safety in institutional settings and led to enhanced monitoring and preventive measures.


n In August and September 2022, an outbreak of E. coli O157:H7 was


linked to contaminated lettuce. A total of 259 people were affected, with 75 hospitalisations and nine cases of HUS.20


The contamination


was traced to sheep faeces washed into lettuce fields during heavy rainfall and flooding, illustrating the impact of environmental factors on food safety.


STEC non-O157 epidemiology There has recently been a significant rise in non-O157 STEC cases and outbreaks seen across the globe. UKHSA and Public Health Scotland (PHS) indicate that non-O157 STEC infection rates have surpassed STEC O157 rates since 2018, with strains O26, O145 and O103 predominating.21


However, as laboratory


diagnostics for STEC other than O157, are not universally undertaken in local laboratories, cases may be under reported. In England between 2016 and


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