Researchers in Denmark have shared lessons learned as part of work on national burden of disease estimates.

The Danish burden of foodborne disease study ranks pathogens and chemicals. Results from 2019 showed the top hazards were Campylobacter, lead, peanut allergy, methylmercury, and Salmonella.

National studies are helpful for risk ranking and identifying priorities for food safety resource allocation, found the study published in the journal Food Control.

The National Food Institute launched an initiative to rank foodborne diseases in Denmark in 2015. The study highlights things learned over more than seven years and has recommendations for other countries planning such work.

Danish experience
In total, 14 hazards are included: Salmonella, Campylobacter, norovirus, Toxoplasma gondii, Listeria monocytogenes, Yersinia enterocolitica, Shiga toxin-producing E. coli (STEC), Hepatitis A virus, Methylmercury, lead, cadmium, inorganic arsenic, acrylamide, and peanut allergy.

The first step in estimating the disease burden of any hazard is to calculate the attributable incidence of disease in the population. Based on this, the burden of disease due to a given hazard can be estimated in terms of disability-adjusted life years (DALYs). 

The 14 hazards caused 133,388 cases, 90 deaths, and 5,928 DALYs in 2019.

Campylobacter caused 5,389 registered cases and 58,983 estimated cases. Total costs were €124 million ($134 million). This included direct costs in the health sector, indirect costs of lost productivity, and estimates of the value of unpaid time lost to morbidity and premature deaths. STEC led to the highest direct health costs, which is due to the larger number of complicated hospitalizations associated with infections.

Lead was linked to an estimated 996 cases, peanut allergy 252 cases, methylmercury 417 cases, and Salmonella 8,657 cases. 

Norovirus was estimated to cause many cases but few DALYs. Toxoplasma gondii and Listeria monocytogenes led to few cases and many DALYs. Hazards causing the lowest burden were hepatitis A virus and cadmium.

Possible interventions
Chemical hazards vary regarding food sources and vulnerable groups, as well as the duration and severity of associated health outcomes.

Intervention strategies are very different. Food safety interventions to control pathogens in foods include pre-harvest control, post-harvest measures, monitoring of foods at retail, investigation of outbreaks to prevent further cases, and raising awareness on food handling practices. Those to prevent exposure to chemical hazards will involve control measures to limit contamination of foods and maximum levels to keep highly contaminated foods off the market.

Actions to control pathogens should have a shorter time from intervention to effect than those needed to control exposures to chemical hazards, which will usually not be measurable for several years due to a long time from exposure to the onset of a health effect.

According to researchers, Ranking foodborne diseases is essential to inform evidence-based food safety priorities and monitor the effect of interventions. If hazards are ranked low, this may indicate current measures are effective and not that resources should be allocated elsewhere.

Plans include expanding the study with more hazards and developing digital platforms for visualization and interaction with the burden of disease estimates.

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