WHO and FAO have published the full report of an exercise that ranked foodborne viruses according to frequency and severity.
The first part of the World Health Organization (WHO) and UN Food and Agriculture Organization (FAO) meetings focused on food attribution, analytical methods, and indicators.
Experts reviewed the scientific literature on foodborne viruses published since the 2008 Joint FAO/WHO Expert Meeting on Microbiological Risk Assessment (JEMRA) report on the topic and the information submitted in response to a call for data.
Viruses and foods
Norovirus was the leading cause of viral foodborne illness, followed by hepatitis A and hepatitis E viruses. Hepatitis A and E were ranked equally but higher than norovirus in clinical severity. The third group contained rotavirus, sapovirus, enterovirus, astrovirus, and enteric adenovirus.
The virus-commodity pairs associated with the highest public health burden included prepared food, frozen berries, and shellfish for norovirus and Hepatitis A. For Hepatitis E, pork was at the top, followed by wild game. However, scientists said there were regional differences.
There wasn’t sufficient data available to rank foods in the third group that may be contaminated by viruses.
Norovirus is estimated to cause 125 million cases of foodborne illness and 35,000 deaths globally each year. Hepatitis A virus causes 14 million cases and 28,000 deaths each year. For Hepatitis E, no such estimate of cases attributed to food exists.
Hepatitis A is a vaccine-preventable infection, and Hepatitis A virus is a notifiable or reportable disease in many countries, meaning healthcare practitioners must report cases to public health officials.
Foods can become contaminated at various points along the farm-to-fork chain, including through contact with infected individuals.
Other issues and viruses
Regarding detection and quantification, current standardized methods are based on detecting viral nucleic acid, which does not necessarily indicate infectivity. Several factors, such as the complexity of the food and low levels of contamination can limit methods.
Viral tick-borne encephalitis has occurred in Europe and is mainly transmitted by tick bites. If infected ticks bite animals like goats, the milk may become contaminated with the virus. Outbreaks with human cases have been associated with raw milk and raw milk cheese.
Nipah virus is transmitted through contact with infected animals, such as fruit bats or pigs, and food and materials contaminated with their saliva or urine. Outbreaks have been traced to the consumption of raw date palm sap contaminated by fruit bats.
Identified gaps included the impact of climate change on foodborne virus transmission, challenges associated with using molecular detection, and the need for cautious interpretation.
Experts recommended that countries consider capacity building to support training and adopting methods for detecting viruses in foods and the environment. This could enhance knowledge on food attribution, support risk analysis, and reduce the burden of viral foodborne disease.
A summary of part two of the meeting, which examined prevention and intervention measures, has been published. The full document will be available shortly as part of the Microbiological Risk Assessment (MRA) series.
FAO’s Clostridium call
In other news, the FAO seeks experts and data on Clostridium species in foods.
According to FAO, limited data are available regarding the control of Clostridium in foods, and strategies to inhibit its growth and toxin production in food sources remain undetermined.
The aim is to collect recent research and surveillance findings about Clostridium botulinum, Clostridium perfringens, and Clostridium difficile and data representing the different commodities and regions associated with diseases caused by these organisms. A meeting will take place in Rome, Italy, in February 2025.
A call for experts hopes to identify scientists who can help assess the global burden of disease caused by Clostridium species related to food, prevalence of contamination, hazard identification, current monitoring work, and prevention strategies. A review of candidates will begin no later than Jan. 6, 2025, and continue until enough suitable people are identified.
In terms of data, the request covers sampling plans and testing methods, outbreak and surveillance data, and other studies to update hazard identification and characterization. Information can be submitted until Jan. 31, 2025. For more information, follow this link.
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