E. coli O157 Outbreak

Publication Date: 29 March 2017

Health Protection Scotland (HPS) has today published the E. coli O157 outbreak report on behalf of the Incident Management Team (IMT) which was established to investigate the national outbreak in summer 2016.

The report confirms that a total of 26 cases of the same strain of E. coli O157 were identified in the outbreak between July and mid-September 2016. Seventeen of the cases required admission to hospital and a three year old child died.

Dr Alison Smith-Palmer, chair of the IMT, said: “This report has been produced on behalf of the multi-agency Incident Management Team and is approved by all team members. The report describes the detailed epidemiological, microbiological, food and environmental investigations and concludes that Dunsyre Blue cheese was the source of this outbreak. It also presents lessons learned and recommendations for improvement.”



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Notes to Editor

Investigation of the outbreak Extensive investigations concluded that the source of the outbreak was the consumption of an unpasteurised cheese – Dunsyre Blue. This conclusion was based on evidence from epidemiological and food chain investigations and supported by microbiological evidence and deficiencies identified at Errington Cheese Limited in the procedures in place for the monitoring and control of STEC.  A summary of this evidence is provided on pages 58-59 of the report. Control of STEC at the cheese manufacturer was reliant on receiving pathogen-free milk but no adequate processes were in place to validate or monitor this.

The investigation did not isolate the outbreak strain from any of the cheese tested. This was not unexpected as the samples from hotels/restaurants where cases consumed the cheese were usually taken more than a month after the cheese was eaten by cases. This meant that the block of cheese from which the case consumed was no longer available for testing. However, other potentially pathogenic STEC and stx negative E. coli O157 were isolated from a number of varieties of cheese produced by Errington Cheese Limited, demonstrating that pathogenic organisms did enter and survive the cheese production process and were present in the final ready to eat product.

Throughout the investigation, the paramount aim of the IMT was the protection of public health. To this end, products considered to pose a risk to the public were withdrawn from the market and the risks communicated to the public and professionals.

E. coli O157 Infection

People usually become unwell with E. coli O157 infection after eating food or drinking water that is contaminated with the faeces from infected animals, or from contact with farm animals or their environments. E. coli is a common bacterium that can live harmlessly in the gut of animals and people. However, some types of E. coli bacteria, including E. coli O157 produce toxins that are harmful to people. These are known as shiga toxin-producing E. coli or STEC.

STEC infection can be asymptomatic, or cause a spectrum of illness from mild non-bloody diarrhoea, through bloody diarrhoea and haemorrhagic colitis, to Haemolytic Uraemic Syndrome (HUS), and other presentations of Thrombotic Microangiopathy (TMA). Children and adults over 60 years old are more likely to develop STEC-related complications than those in other age groups.

The incubation period for E. coli O157 is usually three to four days (range one to 14 days). Symptoms associated with E. coli O157 include stomach cramps, diarrhoea (often bloody), vomiting and occasionally fever. More information on E. coli O157 can be found on the HPS website.

Additional information

  • The multi-agency Incident Management Team (IMT) stood down in October 2016.
  • Food Standards Scotland and South Lanarkshire Council have continued to work with the food business operator.
  • Despite extensive investigation, including looking for other possible food sources, no other link to a majority of cases could be established.
  • All cases were resident in the UK or Republic of Ireland. No further information is being released to protect patient confidentiality.
  • Advice on food safety including recommendations for vulnerable groups is available on the Food Standards Scotland website and on NHS Inform

Due to the on-going investigations by the Procurator Fiscal’s office, it would not be appropriate for Health Protection Scotland to make any further comments.