What makes STEC so dangerous?

STEC are E. coli strains that produce shiga toxins. An infection varies, from mild diarrhea to bloody diarrhea. In some cases, a serious complication develops: hemolytic uremic syndrome, better known as HUS. This syndrome mainly affects young children and the elderly and is characterized by the combination of anemia, platelet deficiency and acute renal failure. Mortality today is low thanks to intensive medical care. Nevertheless, a significant proportion of patients retain permanent kidney problems or problems because of high blood pressure.

How does HUS occur?

The disease occurs when a person consumes contaminated food or water in which STEC is present. The bacteria lodge in the intestine, produce toxins that enter the bloodstream, where they mainly damage the blood vessels in the kidneys. This creates small blood clots that both cause anemia and damage kidney tissue. The first symptoms usually appear five to 10 days after a diarrhea episode and evolve into symptoms such as decreased urine output, pallor, bruising, swelling and, in severe cases, even neurological symptoms.

Recent Belgian outbreaks.

In late August and early September 2025, residents of at least six residential care centers in Flanders were infected with STEC. This resulted in several fatalities. Cases were also confirmed in Brussels and Wallonia. Investigations were conducted by FAVV, Sciensano, Vivalis, Aviq, the Department of Care and the National Reference Center. It looked at insufficiently heated meat products, cross-contamination in mass kitchens and possibly raw milk dairy or fresh vegetables that came in contact with contaminated water or manure as sources of contamination. From the epidemiological data and tracing study, raw minced beef emerged as the most likely source of contamination. However, because no more samples were available from the affected meat lot, this cannot be confirmed with absolute certainty.

The numbers don't lie

In 2023, Europe had more than 10,000 STEC infections - the highest number ever.
Belgium recorded 14 outbreaks with 48 sick that same year, compared to 5 outbreaks in 2022.
In young children under five, HUS is particularly frequent: up to 4.5 cases per 100,000.
Worldwide, nearly three million infections and thousands of HUS cases annually are attributed to STEC.

Why the source is often difficult to find

Determining the exact source of an STEC outbreak is a complex process. The incubation period is often nearly a week. When patients finally seek medical attention, the suspect products are often already off the shelves, simply because their shelf life is shorter. In addition, people eat a wide range of foods in a short period of time, making it difficult to identify which product is responsible. Food distribution is often complex. Therefore, a single contaminated batch may have spread to dozens of locations. On top of that, STEC is not one bacteria, but a collective name for many variants. Only extensive molecular techniques such as whole genome sequencing can link patients with the same strain. This combination of factors explains why investigations often take weeks and sometimes cannot yield a definitive source at all.

More outbreaks in summer, coincidence or not?

The peak of foodborne infections in the summer is no coincidence. Higher temperatures cause bacteria to multiply much faster. At the same time, people eat outside or at events more often, where refrigeration chains are less strict and meat is sometimes insufficiently cooked. The vacation season also brings more international travel and thus exposure to other food chains. Animals excrete more STEC through their manure in the summer, increasing pressure in slaughter and production chains. The harvest period of fruits and vegetables also plays a role, as irrigation with contaminated surface water increases the risk of contamination.

Hygiene on the farm

Cattle are a natural reservoir of STEC. They do not usually get sick themselves, but excrete the bacteria through their manure. How intensely this happens depends on factors such as diet, age, season and farm management. Farmers can significantly reduce infection pressure by implementing strict barn hygiene: prompt and proper manure removal, keeping lying areas clean, hygienic drinking and feeding management and limiting contact with other herds. These measures reduce the likelihood of animals and ultimately carcasses becoming infected. However, complete elimination is impossible. Further down the chain, it is crucial to keep a constant eye on the risk of STEC and strictly apply appropriate management measures.

Farm-to-fork approach for the food industry.

A chain-wide approach is necessary. Food companies would do well to critically screen high-risk raw materials such as beef, raw milk dairy and leafy vegetables. Within the production process, STEC risks should be explicitly included in the hazard analysis, focusing on critical steps such as slaughtering, meat processing and heating.

Achieving a core temperature of at least seventy degrees for two minutes remains the gold standard for inactivating STEC Do not be fooled: just because a product is heated later in the process in no way means that measures earlier in the chain are less important. The combination of time and temperature is based on average STEC contamination levels. If the bacterial concentration rises too high before heating, even proper heating may be insufficient and the risk of foodborne infections remains. This involves core temperature and time, not theoretical process settings. How fast heat penetrates to the core varies greatly from product to product, making assumptions dangerous. Only a thorough and substantiated in-line process validation can prove that the steps applied are really safe in practice. Without that assurance, you run the risk that your products are a threat instead of a guarantee of quality.

Tip: Our experts at Normec Foodlab and Foodcontrol offer tailor-made and practice-oriented solutions for performing effective process validations: theoretical models are tested with surrogate organisms and your company-specific conditions, so that it becomes clear whether heating steps are also effective under real conditions. Laboratory flexibility allows even analytical conditions, such as temperature, to be tailored to the unique needs of your process.

Equally important is the strict separation of raw and ready-to-eat products and the prevention of cross-contamination through personnel and material hygiene. Water quality also plays a crucial role in the vegetable chain.

Clear communication

Clear communication to consumers and the caterer is crucial. Preparation instructions should unambiguously state that high-risk foods such as minced meat products should be fully cooked. For products consumed raw, such as tartare or carpaccio, targeted risk communication is necessary and alternatives or process modifications should be considered whenever possible. Monitoring and traceability complete the picture: only with a quick and efficient recall, can damage be limited in the event of an outbreak.

Accredited assays play a crucial role in STEC prevention. They guarantee that test results are reliable, reproducible and performed according to international quality standards. This is essential for timely identification and management of risks in the food chain. Normec Foodcontrol took a pioneering role in this: it was the first laboratory in Belgium to be officially accredited for STEC analyses, thus confirming its leading position in food safety and quality assurance.

Tip: With a solid monitoring plan, you guarantee food safety and verify that your products meet food safety standards. Contact our experts for accredited STEC analyses that guarantee reliable results.

Extra attention for healthcare facilities

The current outbreaks show that soup kitchens and assisted living facilities need to be extra vigilant. They house the most vulnerable groups, who are at much greater risk of serious illness. Strict control of cooking and cooling chains, consistent separation of raw and prepared food, and accurate traceability down to the pore level are not a luxury but a necessity.

Tip: Hygiene and GMP/GHP inspections in commercial kitchens provide assurance that the measures taken are correctly implemented on a daily basis. An external view, such as Normec Foodcare's audits and inspections, helps identify and prevent potential problems early on.

Conclusion

STEC remains a zoonotic risk that cannot be completely eliminated from the food chain. The recent Belgian outbreaks underscore how quickly an infection can have serious consequences, especially in healthcare facilities. Only a farm-to-fork approach, in which each link in the chain takes responsibility, can reduce the likelihood of new incidents. For the food industry, this means that constant vigilance, process discipline and clear communication are essential to protect consumers and patients.

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