197 | STEC On The Rise? | Insider Warning: Sugar Adulteration! |
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STEC numbers are up: What you need to know
Investigation results? What investigation results (Salmonella in cucumbers)
Food Safety News and Resources
“It’s very very satisfying” - cotton candy scissor work
Sugar warning (and more) in this week’s food fraud news
Happy Monday!
The European Commission recently published a report about Shiga toxin-producing Escherichia coli (STEC), and the number of reported infections is higher than ever.
But what’s the full story behind these numbers? In this week’s issue, I unpack the scary stats about STEC in 2025 and provide some context.
Also this week, an important warning about an adulteration problem in sugar with the potential to affect many processors globally. And see what happens when you take some scissors and a tongue to a couple of big chunks of cotton candy (fairy floss).
Enjoy,
Karen
P.S. Big shoutout to 👏👏 Campbell from the US, Ingrid and Jack from Australia 👏👏 for upgrading to a paid subscription and to 👏👏 Cathy and Jenny 👏👏 for renewing. Every subscription makes a difference, thank you!
STEC infections are up. Here’s what you need to know.
In May 2025, the European Commission published a report about Shiga toxin-producing Escherichia coli (STEC), and the number of reported infections is at record levels.
Here’s what you need to know, even if you’re not in Europe.
What is Shiga toxin-producing Escherichia coli?
Shiga toxin-producing Escherichia coli (STEC) are a group of E. coli bacteria that produce toxins known as Shiga toxins, which can cause illness in humans. While most E. coli strains are harmless and naturally found in the intestines of people and animals, STEC strains can lead to serious gastrointestinal disease, including diarrhoea and sometimes more severe complications.
Infection typically occurs through ingestion of contaminated food or water, or direct contact with infected animals or people.
If consumed, STEC bacteria can multiply inside human intestines and produce toxins which cause symptoms that include bloody diarrhoea, hemorrhagic colitis (HC) and haemolytic uremic syndrome (HUS).
The most well-known STEC serotype is O157:H7, which lives harmlessly in the guts of healthy cattle but causes serious illness in humans. Other serotypes of E. coli can also produce Shiga toxins and cause illness in humans, including types from serogroups O26, O103, O111, O121, O45, and O145.
How common is STEC?
The prevalence of STEC in foods and the environment is low compared to the prevalence of ordinary (non-Shiga-toxin-producing) E. coli. Its prevalence varies by region, season and food type.
For example, of 600 soil samples collected in Ireland in 2007 to 2008, just 0.7% contained STEC bacteria, while 1.9% of 1,200 bovine faecal samples contained STEC (source).
A study of 110 beef samples collected from a slaughterhouse in Iran in 2020 found 70% contained E. coli but only 7% contained STEC (source). In another study, 88% of 294 samples of various fresh foods purchased in Turkiye contained E. coli, while only 10% contained STEC (source).
How does STEC get into food (and people)?
STEC is found in the guts of healthy ruminant animals, particularly cattle. It contaminates beef meat via cross-contamination of meat with faeces during processing.
Other foods can become contaminated with animal faeces during growing, handling and packing, including unpasturised milk and cheese and vegetables. Untreated drinking water can also contain STEC from faecal contamination.
In addition to food and water sources, humans are also exposed to STEC via direct contact with animals such as at petting zoos or farms.
What does the latest data tell us?
In May 2025, the European Commission published an analysis of STEC infections that occurred in 2023, as reported by 30 European countries. Here are the key takeaways from the report.
Total case numbers were high. Case rates for confirmed STEC infections were up by 22% compared with the previous year, to 3.2 cases per 100,000 people, their highest since European-wide surveillance began in 2007.
Infections are seasonal, with higher case numbers in the summer months.
Young and old people were worst affected, with case rates for the 0-4 age group about four times greater than for the general population. Young (0-4 years) and old (> 65 years) accounted for 20% and 23% of cases, respectively. Most of the 32 reported fatalities were among older people (63%), with 23% of those having had HUS. All remaining fatalities were children younger than 15, most of whom (83%) had HUS.
HUS cases did not increase. The number of cases of HUS was comparable between 2022 and 2023, with 522 cases of HUS among the 10,901 total cases in 2023.
Case numbers and case rates vary significantly between countries. The worst-affected countries had more than 20 cases per 100,000 population, but 11 countries in southern and eastern Europe reported fewer than 0.6 cases per 100,000 population. The countries with the highest numbers of cases were Denmark, Germany and Ireland, with Denmark and Germany reporting large increases compared to the previous year. These three countries accounted for more than half of all cases in the European Union/European Economic Area (EU/EEA).
‘Rare’ serogroups were responsible for many illnesses. The most frequently reported serogroups were O157 (19.8%), O26 (16.7%) and O146 (5.7%), however, the six most frequently reported serogroups accounted for only 55% of cases for which the serogroup was identified, meaning a significant proportion of cases were caused by ‘rare’ serogroups.
HUS was caused most often by O26. For cases of HUS, O26 was the most frequently reported serogroup (41.1%) followed by O157 (21.5%), O145 (7.4%) and O80 (5.2%). O26 has been the reported serogroup of HUS cases since 2016.
The virulence gene stx2f is increasing. There has been an increasing trend in the number of cases with stx2f-positive isolates, with 2023 having the highest number since the start of reporting in 2009. This variant of the gene is most often associated with serotype O63:H6. Isolates from severe cases such as HUS often contain the stx2 gene, however, gaps in diagnostic methods could leave stx2f undetected.
Changes to diagnostic test methods likely influenced the results. The report implies that a switch to PCR-based methods from traditional cultivation diagnostics was an influencing factor for the increase in cases, particularly for Denmark, Germany and Norway.
Outbreak food sources in 2023 included raw (unpasteurised) milk cheese, ready-to-eat salad/ iceberg lettuce, buttermilk and bovine meat.
Preventive methods are unchanged. Good hygiene practices for food preparation and at petting farms and zoos, as well as adequate cooking of food, particularly beef, and pasteurisation of dairy foods, remain the primary methods of prevention.
Key takeaways
While the food safety media has been concerned about the apparent increase in STEC infections from food, the authors of the European report attribute some of the increase to improved diagnosis, with countries that use PCR methods reporting the highest rates of illness per capita.
The number of HUS cases remained steady from 2022 to 2023 and the serogroup most frequently associated with HUS, O26, has not changed since 2016. Young and old people remain the worst affected, accounting for all fatalities in 2023, with young fatalities more likely to have been affected by HUS.
Food sources and mitigations for foodborne illness are unchanged.
In short: Confirmed cases of Shiga toxin-producing Escherichia coli (STEC) are at records highs in Europe, but at least some of the increase is likely due to improved diagnostic tests 🍏 The number of cases of HUS has not increased 🍏 There has been an increasing trend in the number of cases with stx2f-positive isolates (a virulence gene), with 2023 having the highest number since the start of reporting in 2009 🍏 Common serogroups accounted for only 55% of cases 🍏 Food sources of infections have remained similar from year to year 🍏 Prevention methods and mitigations are unchanged 🍏
Main source:
European Centre for Disease Prevention and Control (2025) STEC infection. In: ECDC. Annual epidemiological report for 2023. Stockholm: ECDC; 2025. Available from: https://www.ecdc.europa.eu/sites/default/files/documents/shiga-toxin-producing-escherichia-coli-annual-epidemiological-report-2023.pdf
More about STEC from The Rotten Apple
🍏 How Does E. coli Cause Leafy Greens Outbreaks? | Issue 53 🍏
🍏 E. coli survival and growth on leafy greens | Issue 136 🍏
🍏 E. coli in leafy greens - an extreme weather event causes an outbreak | Issue 156 🍏
Quick take: Investigation results for Salmonella in cucumbers (USA)
The US Food and Drug Administration (FDA) has published its final report into the investigation of the 2025 outbreak of salmonellosis linked to fresh whole cucumbers, after the Centers for Disease Control and Prevention (CDC) declared the outbreak over.
There were 69 illnesses, 22 hospitalisations, and 0 deaths.
Epidemiological and traceback information indicated the source of the illnesses was cucumbers grown by Bedner Growers of Florida, with samples of these cucumbers found to contain Salmonella montevideo matching the illness strain.
They also found Salmonella braenderup in the samples, with the strain matching illnesses in a 2024 outbreak, which had also been epidemiologically linked to the same grower.
But what about the root cause?
The FDA’s statement about this investigation contains zero information about root cause analyses or follow-up preventive actions. Their final conclusion says nothing about what will be done to prevent such outbreaks from happening in future, stating “Food safety is a shared responsibility that involves growers, packers, distributors, retailers, and regulators. While FDA’s investigation is complete, FDA is committed to working with all stakeholders to advance critical work to improve prevention of future outbreaks.”
“Food safety is a shared responsibility that involves growers, packers, distributors, retailers, and regulators. While FDA’s investigation is complete, FDA is committed to working with all stakeholders to advance critical work to improve prevention of future outbreaks.” The FDA’s comment on the outcome of their investigation.
Will the grower face any repercussions? Prosecution? Has the grower made any changes to their irrigation, harvesting, or handling methods since the outbreak? Has anyone examined on-farm water sources or looked for evidence of vertebrate pest problems on this farm?
How long until cucumbers from this same farm sicken more people?
Source: Outbreak Investigation of Salmonella: Cucumbers (June 2025) | FDA
Food Safety News and Resources
Our food safety news and resources roundups are expertly curated and never boring.
In this week’s roundup: mass poisoning of kindergarten children after cooks add lead paint to their food 😮
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Cotton Candy Art (Just for Fun)
“If you have never taken scissors to cotton candy, I highly recommend it. It is very very satisfying,” says @artofsucre (AOS) in this YouTube short.
Warning: This video contains a construction method that food safety experts may find disturbing.
Below for paying subscribers: Food fraud news, horizon scanning and incident reports
📌 Food Fraud News 📌
In this week’s food fraud news:
📌 Bulk sugar fraud on a large scale - insider’s warning!
📌 Methods for vegetable oil, roasted coffee beans, fresh vs frozen poultry
📌 Warnings for perppermint oil
📌 Incidents with artificial milk, cinnamon and seasoning
Sugar alert (insider’s warning)!!!
I have an automated system for collecting intelligence from around the world, but it doesn’t pick up everything. Here’s a big one it missed.
Last week, a reader got in touch with me to tell me about a problem with the potential to affect many importers and processors globally. He told me