Researchers have reported the food attributable portions of disease for four important pathogens in the United Kingdom.
Findings will be used to support future Food Standards Agency (FSA) studies estimating the burden of foodborne disease.
A literature review was conducted to provide source attribution estimates for enteropathogenic E. coli (EPEC), sapovirus, hepatitis A virus (HAV) and Toxoplasma gondii. It included seven studies for Toxoplasma gondii, nine for HAV, one for EPEC, and five for sapovirus.
As there was only one study for EPEC, results for diarrheagenic E. coli (DEC) types, not including Shiga toxin-producing E. coli (STEC) were included. This suggested between 25 and 55 percent of DEC disease could be attributed to foods.
Key findings
Data suggests a larger percentage of foodborne transmission for EPEC, and Toxoplasma gondii compared to sapovirus and HAV. Thirteen studies published after 2012 were included. They estimated foodborne disease percentages as 64 percent for EPEC; 10 percent to 42 percent for HAV; 13 percent to 16 percent for sapovirus; and 28 percent to 61 percent for Toxoplasma gondii.
Previous studies commissioned by the FSA estimated the foodborne burden of sapovirus and reviewed the risk of infection from foods for Toxoplasma gondii. The burden of disease linked to HAV and EPEC in the UK had not been investigated before.
Fresh produce was the primary foodborne transmission pathway for HAV, with estimates ranging from 45 percent to 95.4 percent, and for sapovirus at 58.3 percent. Pork was a significant transmission pathway for Toxoplasma gondii, with estimates between 20 percent and 41 percent.
Using data from an intestinal infectious disease survey, FSA aims to estimate the number of patients, general practice visits, and hospitalizations from September 2023 to August 2025 caused by selected pathogens. To calculate this, estimates of the percentage of disease attributable to foods for each pathogen are needed. Results should be published in late 2026.
Researchers said high variability was observed in results of the studies but the figures are useful for the FSA to calculate the burden of foodborne infections in the UK. Estimates from 2018 suggest the UK has 2.4 million cases of foodborne disease per year.
Progress on pathogen thresholds
In other news, at a recent FSA Board meeting, attendees heard about the limitations of the current system for monitoring levels of foodborne disease.
Thresholds for key pathogens were agreed by FSA in 2018. They are used to ensure notable increases trigger action and signal the need for investigation. Pathogens are Campylobacter, Salmonella, Shiga toxin-producing E. coli (STEC) and Listeria monocytogenes.
Consensus among attendees at a workshop in December 2024 was that thresholds remain a sensible approach. For Salmonella and Campylobacter, numbers are unlikely to be dominated by outbreaks. A rise in cases sufficient to cross the threshold would indicate a more systemic issue, such as with the pathogen itself, controls, or changes in consumer behavior.
Listeria and STEC have a relatively low number of reported cases. One large or multiple smaller outbreaks can lead to a breach of the threshold level. There is ongoing discussion about whether thresholds are appropriate for these pathogens.
It was proposed that the Salmonella threshold would be refreshed to account for the impact of reporting isolates from all relevant sample types, such as fecal and non-fecal samples, including blood and urine. The Campylobacter limit is likely to remain unchanged.
The Listeria monocytogenes threshold will be redone, to reflect a decrease in cases since limits were first created and the STEC threshold will be based on the main serotypes related to human cases rather than solely O157.
Old thresholds were 71,300 lab reports per year in the UK for Campylobacter, 8,500 to 9,500 for Salmonella, 800 to 1,500 for E. coli O157 and 150 to 250 for Listeria. At the meeting, the board agreed for work to continue and the aim is to publish revised thresholds in the next year.
New thresholds will be calculated based on data from 2015 to 2023, excluding the COVID-19 pandemic years 2020 and 2021. A review of these levels every five years was also proposed.
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