Norovirus, hepatitis A and E are now the leading causes of foodborne illness worldwide | Waterloo News

Foodborne viruses are a global health problem, and the type, severity, and impact of illness vary over time and among different communities and countries.

Dr. Shannon Majowicz, associate professor in the School of Public Health Sciences, was in Rome, Italy last month to participate in the FAO/WHO Joint Expert Meeting on Microbiological Risk Assessment of Viruses in Food (JEMRA) held by the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO).

During the meeting, the expert committee conducted a global review into the frequency and clinical severity of viruses associated with foodborne illness in humans. They emphasized that norovirus is the leading cause of viral foodborne illness, followed by hepatitis A and hepatitis E.

“Not only is norovirus highly contagious, but even tiny amounts of norovirus can make you sick,” Machovich said. “Data from 2010 tells us that there are approximately 125 million cases globally each year, with 35,000 people deaths. The World Health Organization’s Foodborne Disease Burden Epidemiology Reference Group is currently working to update these estimates using data from recent years.”

Hepatitis A and E ranked highest when considering clinical severity alone.

“Hepatitis E is not as serious a problem in Canada as it is in some other countries,” Macovic said. “The viruses that cause most foodborne illnesses vary between countries and over time.”

Majowicz explained that both norovirus and hepatitis A are spread through food and water contaminated with infected feces. The committee found that foods with the highest global public health risk associated with both viruses include prepared foods, frozen berries and shellfish, with significant variation across regions.

Hepatitis E is different in that it is a zoonotic pathogen, meaning it can be transmitted from animals to humans. While the virus can be spread through contaminated food and water, it has also been linked to animal products. Experts have concluded that the foods currently posing the highest public health risk for hepatitis E globally are pork and game.

“One of my main areas of expertise is disease burden, which means understanding how big of a problem foodborne infections like these viruses really are,” Macovic said. “This includes not just how many cases or deaths there are, but also any short- or long-term lasting health consequences. For example, one of the long-term effects of hepatitis A in some people is liver problems.”

While there are currently no hepatitis E or norovirus vaccines approved in Canada, the hepatitis A vaccine is highly preventable.

Prior to joining Waterloo, Majowicz worked in federal public health for more than 10 years and has been a member of the World Health Organization’s Foodborne Disease Burden Epidemiology Reference Group since 2021. She manages Waterloo’s foodborne illness epidemiology team. She is one of two Canadians on a panel of 23 experts from around the world.

The Committee recommends that all Member States continue to use methods for detecting viruses in food with a view to improving understanding of food properties and risks.

Read the meeting abstract here.