The Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO) Joint Expert Meeting on Microbiological Risk Assessment (JEMRA) has published a report ranking the most important foodborne viruses and virus-food commodity pairings.

Human norovirus was identified as the leading cause of foodborne illness. Hepatitis A virus and hepatitis E virus were ranked equally below norovirus in terms of frequency, but higher than norovirus in terms of clinical severity.

When considering both frequency and severity, the ranking for foodborne viruses fell into three groups as follows:

1. Norovirus
2. Hepatitis A and hepatitis E, ranked in order
3. Rotavirus, sapovirus, enterovirus, astrovirus, and enteric adenovirus, ranked in order.

Virus-food commodity pairs with the highest global public health burden were also ranked for norovirus, hepatitis A, and hepatitis E:

• For norovirus: Prepared foods, frozen berries, and shellfish, ranked in order
• For hepatitis A: shellfish, frozen berries, and prepared foods, ranked in order
• For hepatitis E: Pork and wild game, ranked in order.

Every year, norovirus is estimated to cause 125 million cases of foodborne illness and 35,000 deaths globally. Hepatitis A is estimated to cause 14 million cases of foodborne illness and 28,000 deaths around the world, annually. Hepatitis E is unique in that it is a zoonotic pathogen with many asymptomatic animal reservoirs, notably swine. Although there is no global estimation of foodborne cases of hepatitis E infection, countries that have explored the issue have concluded that their prior estimates are significantly too low.

The report highlighted international and national standard methods for detection and quantification of human norovirus and hepatitis A virus in foods since the last JEMRA report on foodborne viruses in 2008. These methods include International Organization for Standardization (ISO) methods ISO-15216-1:2017 and ISO-15216-2:2019, which are likely to become benchmarks for validation of new methods. ISO methods for hepatitis E virus detection in meats and meat products are also in development.

Aside from ISO, national methods have been validated and are being used by some laboratories. Existing methods can be limited by factors like food composition complexity and low contamination levels, and come with challenges in interpretation, applicability, integration with sequencing technologies, and implementation in low-resource countries.

JEMRA underlines the need for infectivity assays for wild-type viruses, relative to detection. The expert committee also recommends that member countries consider capacity-building to support training for and adoption of detection methods for foodborne viruses.