FAO/WHO Expert Committee Advances Foodborne Virus Research for Codex Guidance Enhancement

In a recent development, the Joint Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO) Expert Meeting on Microbiological Risk Assessment (JEMRA) has conducted a comprehensive review of scientific advancements and data concerning foodborne viruses. This review serves as a critical step to support ongoing efforts to update the Codex Alimentarius General Principles of Food Hygiene to control viruses in foods (CXG-079-2012).

The Codex Committee on Food Hygiene (CCFH) had specifically tasked JEMRA with conducting an up-to-date evaluation of foodborne viruses, their association with high-risk food commodities, analytical methods for detecting enteric viruses in food, and the possible utility of viral indicators for contamination. JEMRA meticulously examined scientific literature related to foodborne viruses, marking a significant update since its last report on viruses in foods in 2008.

Foodborne Viruses and High-Priority Commodities

To determine the viruses and foods of greatest public health concern in the context of foodborne illnesses, JEMRA considered the frequency and severity of disease. Human norovirus emerged as the most prevalent cause of viral foodborne illnesses, with hepatitis A and hepatitis E viruses closely following. While hepatitis A and hepatitis E shared an equal ranking, they were rated higher than norovirus in terms of clinical severity. When factoring both frequency and severity, the viruses were categorized into three groups:

1. Norovirus

2. Hepatitis A and hepatitis E viruses

3. Rotavirus, sapovirus, enterovirus, astrovirus, and enteric adenovirus, respectively, in descending order.

Furthermore, JEMRA assessed global data and identified virus-commodity pairs with the highest global public health burden related to specific viruses, with notable findings including:

- For norovirus: Prepared food ranked highest, followed by frozen berries and shellfish.

     - For hepatitis A: Shellfish, frozen berries, and prepared foods were equally rated.

     - For hepatitis E: Pork led, followed by wild game.

JEMRA recognized the lack of sufficient data to rank foods potentially contaminated by astrovirus, sapovirus, enterovirus, enteric adenovirus, and rotavirus, emphasizing the need for enhanced monitoring and investigation of these foodborne illnesses and associated commodities. They also highlighted the complexity of ranking virus-commodity pairs on a global scale due to regional variations in foods linked to foodborne illnesses.

Analytical Methods and Indicators for Foodborne Viruses

Since the last JEMRA report in 2008, international and national standard methods have been developed and validated for the detection and quantification of human norovirus and hepatitis A virus in foods. These methods are now in use in various countries. Notably, the International Organization for Standardization (ISO) methods ISO-15216-1:2017 and ISO-15216-2:2019 are widely employed for the detection of norovirus and hepatitis A virus in different commodities, setting a benchmark for new method validation. These methods cover a range of matrices, including leafy greens, soft fruits, and shellfish. ISO methods for detecting hepatitis E virus in meats and meat products are also under development.

In addition to ISO methods, several national methods have been validated and are in use by laboratories. Current standardized methods involve the detection of viral nucleic acid, which does not necessarily indicate infectivity. Challenges faced by these methods include the complexity of food composition and low contamination levels. Enhancing the accuracy and application of these methods, extending them to other viruses and matrices, incorporating sequencing technologies, and implementation in resource-limited countries are some of the pressing issues. JEMRA emphasized the need for sharing laboratory and epidemiological data at national, regional, and international levels to enhance the understanding and control of foodborne viruses.

Exploring potential viral indicators for contamination, such as bacteria, bacteriophages, and plant and animal viruses, is an area of ongoing research. While these indicators have shown variable utility in environmental waters and shellfish, further investigation is required to assess their suitability for other commodities linked to foodborne virus contamination.

Needs Assessment and Data Gaps

JEMRA underscored the need for infectivity assays for wild-type viruses that can be used alongside detection methods. Distinguishing infectious from noninfectious viruses using molecular amplification remains a challenge, and while in vitro propagation models for human norovirus and hepatitis E virus exist, they are not yet suitable for routine use.

JEMRA recommended that member countries enhance their capacities to support the training and adoption of virus detection methods in foods and the environment. This approach can bolster knowledge of food attribution, bolster risk analysis, and help mitigate the burden of viral foodborne diseases on a global scale. Collaborative global efforts are essential to mitigate the anticipated rise in public health risks associated with foodborne illnesses, driven by population growth, climate change, and the globalization of food supply chains.