These Are the Most Viral Foodborne Illnesses, According to the World Health Organization

The Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) collaborated on a new report ranking the most viral foodborne illnesses.

The Joint Expert Meeting on Microbiological Risk Assessment (JEMRA) report, which was published in December 2024, found that the human norovirus is the leading cause of foodborne illness. As the report stated, it came to this conclusion after conducting a “review of the viruses known to be associated with human foodborne illness. The frequency of illness, and the clinical severity of disease, as well as virus–food commodity pairs, were ranked in the context of foodborne illness.” The review took a semi-quantitative approach, meaning it took into account both hard numbers as well as the “expert knowledge” of the authors of the report. 

As for what foods were most likely to be associated with norovirus, the committee found it’s usually prepared foods, frozen berries, and shellfish (ranked in order). 

The Centers for Disease Control and Prevention (CDC) explains that diarrhea, vomiting, nausea, and stomach pain are the most common symptoms of norovirus. However, fever, headache, and body aches can also be present. 

“Each year, norovirus is estimated to cause 125 million cases of foodborne illness and 35,000 deaths globally,” the authors of the joint report added. According to the CDC, it causes 2,500 outbreaks in the U.S. alone, accounting for 58% of foodborne illnesses in the nation. “Norovirus is highly infectious, and outbreaks have been linked to foods with low levels of contamination. Viral contamination can occur across the whole food chain. Severe outcomes, including hospitalization and death, mainly affect children less than five years of age, the elderly, and immunosuppressed individuals who may shed the virus for extended periods of time.” 

Joining norovirus on a list nobody would want to be a part of is hepatitis A, which ranked second as the most viral. According to the report, it causes 14 million cases of foodborne illness a year and 28,000 deaths across the globe. 

“There are significant regional differences in the proportion of hepatitis A cases that are attributed to food due to endemic prevalence and vaccine utilization,” it added. “International trade of foods plays an important role in transmission to susceptible populations. Wider compliance with international standards, e.g., good agricultural and hygiene practices, is likely to reduce global transmission.” The report added that it’s most often associated with shellfish, frozen berries, and prepared foods as well (ranked in order). 

And in third is the hepatitis E virus, which the report stated is “unique among the foodborne viruses” as it’s “a zoonotic pathogen with many asymptomatic animal reservoirs, notably swine.” It noted that there is no global estimation of cases attributed to food but that countries that have investigated its spread “found that their prior estimates are too low by one order of magnitude or more.” Hepatitis E, the report added, can cause severe illness, especially in those with underlying health conditions, and can lead to cirrhosis of the liver and neurological damage 

“Undercooked pig products, including liver or raw sausage containing liver or blood, as well as liver pâté, are the main foods contaminated by hepatitis E virus,” it warned. 

However, a number of other viruses, including astrovirus, sapovirus, enterovirus, enteric adenovirus, and rotavirus, could actually outnumber these. The team stated that there was a “lack of sufficient data to conduct a ranking of foods that may be contaminated” by these viruses.

While all of this is alarming, the authors also stated that improved surveillance data and better reporting of foodborne cases of these illnesses could help control or prevent their spread. 

“The Expert Committee recommends that member countries consider capacity-building to support training and adoption of these methods for detecting viruses in foods and the environment,” it concluded. “This approach has the potential to enhance knowledge on food attribution, support risk analysis, and reduce the burden of viral foodborne disease worldwide. Appropriate global actions will help alleviate the anticipated increase in public health risk from viral foodborne illness arising from population growth, the climate crisis, and globalization of food supply chains.” And in the end, better training and detection could save millions of lives worldwide. See the full report at iris.who.