Can foodborne illness estimates from different countries be legitimately compared?: case study of rates in the UK compared with Australia, Canada and USA.

OBJECTIVE: Mathematical models have gained traction when estimating cases of foodborne illness. Model structures vary due to differences in data availability. This begs the question as to whether differences in foodborne illness rates internationally are real or due to differences in modelling approaches.Difficulties in comparing illness rates have come into focus with COVID-19 infection rates being contrasted between countries. Furthermore, with post-EU Exit trade talks ongoing, being able to understand and compare foodborne illness rates internationally is a vital part of risk assessments related to trade in food commodities. DESIGN: We compared foodborne illness estimates for the United Kingdom (UK) with those from Australia, Canada and the USA. We then undertook sensitivity analysis, by recreating the mathematical models used in each country, to understand the impact of some of the key differences in approach and to enable more like-for-like comparisons. RESULTS: Published estimates of overall foodborne illness rates in the UK were lower than the other countries. However, when UK estimates were adjusted to a more like-for-like approach to the other countries, differences were smaller and often had overlapping credible intervals. When comparing rates by specific pathogens, there were fewer differences between countries. The few large differences found, such as virus rates in Canada, could at least partly be traced to methodological differences. CONCLUSION: Foodborne illness estimation models are country specific, making international comparisons problematic. Some of the disparities in estimated rates between countries can be shown to be attributed to differences in methodology rather than real differences in risk.

Estimating deaths from foodborne disease in the UK for 11 key pathogens.

OBJECTIVE: To estimate the number of deaths from foodborne disease in the UK from 11 key pathogens. DESIGN: Four different models were developed using data from a range of sources. These included enhanced surveillance, outbreaks, death certificates and hospital episode statistics data. For each model, median estimates were produced with 95% credible intervals (CrI). The results from the different models were compared. RESULTS: The estimates for foodborne deaths for each pathogen from the different models were consistent, with CrIs largely overlapping. Based on the preferred model for each pathogen, foodborne norovirus is estimated to cause 56 deaths per year (95% CrI 32 to 92), foodborne Salmonella 33 deaths (95% CrI 7 to 159), foodborne Listeria monocytogenes 26 deaths (95% CrI 24 to 28), foodborne Clostridium perfringens 25 deaths (95% CrI 1 to 163) and foodborne Campylobacter 21 deaths (95% CrI 8 to 47). The considerable overlap in the CrIs means it is not possible to make any firm conclusions on ranking. Most of these deaths occur in those aged over 75 years. Foodborne deaths from Shigella, Cryptosporidium, Giardia, adenovirus, astrovirus and rotavirus are all rare. CONCLUSIONS: We estimate that there are 180 deaths per year in the UK (95% CrI 113 to 359) caused by foodborne disease based on these 11 pathogens. While this is a small fraction of the estimated 2.4 million cases of foodborne illness per year it still illustrates the potential severity of these illnesses demonstrating the importance in continuing efforts to reduce these infections.