The story of foodborne illness has long been dominated by bacterial villains like Salmonella and E. coli. But public health experts are increasingly sounding the alarm about a different, more elusive class of pathogens that are now recognized as the leading cause of foodborne sickness worldwide: viruses. While names like norovirus and hepatitis A may be familiar, their profound impact on global health and the complex challenges they present to our food supply are only now coming into full focus.
Recent analyses confirm that viruses are responsible for the greatest number of illnesses from foodborne outbreaks. In the United States alone, despite having one of the world’s safest food supplies, an estimated 48 million foodborne illnesses occur annually, and enteric viruses cause a staggering 59% of them. The global scale is even more sobering, with approximately 600 million foodborne illnesses and 420,000 deaths each year.
What makes these viral threats so formidable is their nature. Unlike bacteria, viruses cannot grow on food; they are simply passengers, but incredibly hardy ones. They can persist on surfaces, hands, and in the environment for extended periods, waiting for an opportunity to infect a host. They are also notoriously difficult to detect in food products, and often, the first sign of their presence is an outbreak of sick people. As our food supply chains become more global and interconnected, the potential for these viruses to spread rapidly has never been greater. This reality is forcing a fundamental shift in how scientists, regulators, and the food industry think about protecting our plates.
The Leading Culprits: Norovirus and Hepatitis A
At the forefront of this viral wave are two well-known but persistently problematic pathogens: norovirus and hepatitis A virus (HAV). A landmark 2024 report by the World Health Organization (WHO) and the UN Food and Agriculture Organization (FAO) ranked these viruses as the top foodborne viral threats to public health.
Norovirus is the undisputed heavyweight champion of foodborne illness. It is estimated to cause about 125 million foodborne cases and 35,000 deaths globally each year. In the U.S., it is the leading cause of foodborne illness, responsible for roughly 5.46 million cases annually. The virus is infamous for its brutal efficiency. It is highly contagious, requiring only a few viral particles to cause infection, and it spreads easily through contaminated food, water, surfaces, and direct person-to-person contact.
The symptoms—violent vomiting, diarrhea, nausea, and abdominal pain—are debilitating but typically short-lived. However, for vulnerable populations like the very young, elderly, or immunocompromised, the resulting dehydration can be severe and require hospitalization. Recent data underscores its relentless presence. As of late December 2024, more than 22% of norovirus tests in the U.S. were returning positive, a significant increase from the same time the previous year. Outbreaks are frequently linked to ready-to-eat foods contaminated by an ill food handler, as well as produce like leafy greens and shellfish, particularly oysters, which filter the virus from contaminated water.
Hepatitis A presents a different, more insidious danger. While it causes fewer annual cases than norovirus—an estimated 14 million foodborne illnesses globally—it is far more severe, resulting in approximately 28,000 deaths each year. Unlike the rapid-onset gastroenteritis of norovirus, hepatitis A attacks the liver. After an incubation period of weeks, it can cause fever, fatigue, loss of appetite, nausea, and jaundice (yellowing of the skin and eyes). The illness can last for weeks or months, and in rare cases, lead to acute liver failure and death.
The virus is primarily spread through the “fecal-oral” route, often when an infected person, who may not yet show symptoms, handles food without proper hand hygiene. Like norovirus, it has been linked to outbreaks from contaminated fresh and frozen berries, shellfish, and prepared foods. A critical distinction, however, is that hepatitis A is vaccine-preventable. This tool adds a powerful layer of defense that is not available for most other foodborne viruses.
The Emerging Concern: Hepatitis E and Other Viral Threats
Beyond the top two, the FAO/WHO report highlighted a third virus of major concern: hepatitis E (HEV). For years, hepatitis E was considered a travel-related disease in wealthy nations, associated with contaminated water in developing regions. Today, it is recognized as an emerging foodborne threat in industrialized countries, including those in Europe and North America.
In places like Germany, the majority of reported hepatitis E cases are now acquired locally and are linked to a zoonotic genotype (HEV-3) that is widespread in domestic pigs and wild boars. The animals show no symptoms, but the virus can be transmitted to humans through the consumption of raw or undercooked meat and liver products from infected animals. Studies in Germany have found HEV antibodies in over 15% of the general population, indicating past infection, though most cases go unnoticed. For most, the infection is mild or asymptomatic, but it can cause severe, chronic liver disease in immunocompromised individuals and is particularly dangerous for pregnant women in certain regions.
The viral risk profile extends further. The FAO/WHO expert group identified a third tier of foodborne viruses that include rotavirus, sapovirus, enterovirus, and astrovirus. These viruses, often overshadowed by their more famous counterparts, are significant causes of acute gastroenteritis worldwide. Astrovirus outbreaks, for example, frequently result from foods contaminated by infected food handlers or the consumption of tainted shellfish or produce. While typically causing less severe illness, they contribute substantially to the overall burden of foodborne disease, especially in children.
Why Viruses Are a Uniquely Stubborn Problem
Controlling foodborne viruses presents a suite of challenges that differ sharply from battling bacteria. First, they are extremely resilient in the environment. Hepatitis E virus, for instance, is stable against acids, alkalis, and high salt concentrations, and can remain infectious on surfaces for weeks to months. Norovirus can survive on countertops, door handles, and utensils for days, resisting many common disinfectants.
Second, detection is a major hurdle. Current standardized testing methods often look for viral genetic material (nucleic acids) in food, but finding this material does not definitively prove the virus is still infectious and capable of causing disease. The levels of contamination can be very low, yet still sufficient to cause an outbreak, making them hard to find in complex food matrices like berries or salad greens.
Perhaps the most difficult challenge is the human element. As food safety expert Jeffrey LeJeune has pointed out, asymptomatic carriage is a major problem. Food workers or harvesters can shed viruses without knowing they are infected, leading them to be less vigilant about hygiene than someone who feels ill. A single infected person preparing a salad or handling fresh produce can inadvertently sift hundreds.
Furthermore, many high-risk foods are consumed raw or lightly cooked. Oysters, berries, leafy greens, and certain sausages made with raw liver are valued for their fresh, unprocessed qualities, but these very attributes bypass the most reliable kill-step for viruses: thorough cooking.
Frontline Defenses: From Handwashing to High-Tech Solutions
Given the difficulties of detection and removal, the cornerstone of defense against foodborne viruses remains prevention. Experts universally agree that the first and most important line of defense is strict, uncompromising hygiene.
Hand hygiene is non-negotiable. Proper and frequent handwashing with soap and water is the single most effective practice to break the chain of transmission, especially for food handlers. Safe food handling practices, including using clean utensils and surfaces, preventing cross-contamination, and rigorously washing fruits and vegetables, are essential in both commercial and home kitchens.
For specific viruses, vaccination offers targeted protection. The hepatitis A vaccine is highly effective and is recommended for travelers to endemic areas, people with chronic liver disease, and as a routine childhood immunization in many countries. Some experts are now exploring incentives for vaccinating food workers in high-risk settings as part of a broader prevention strategy.
On a systemic level, regulatory agencies are adapting their strategies. In early 2025, the U.S. Food and Drug Administration (FDA) rolled out a new strategy focused on preventing enteric virus outbreaks linked to fresh and frozen berries. The plan emphasizes promoting compliance with safety requirements, urging the global berry industry to ensure consistent sanitary practices from field to package, and broadening scientific knowledge about how viruses persist and spread in these products. As Conrad Choiniere, PhD, director of the FDA’s Office of Microbiological Food Safety, stated, collaboration between regulators, industry, and other stakeholders is critical to developing these proactive defenses.
Finally, thorough cooking is a guaranteed solution where applicable. Heating food to a sufficient temperature destroys viral pathogens. Public health agencies stress that cooking pork and wild boar meat thoroughly can effectively inactivate hepatitis E virus, and avoiding raw or undercooked shellfish significantly reduces the risk of norovirus and hepatitis A.
Analysis & Next Steps
The evolving understanding of foodborne viruses marks a significant pivot in food safety. What’s new is the formal, data-driven recognition by global bodies like the FAO and WHO that viruses—not bacteria—are the predominant cause of foodborne illness, and that this threat includes both perennial problems like norovirus and emerging zoonotic risks like hepatitis E. This matters because it shifts the priority from simply responding to bacterial contamination to building systems that address the unique stealth, resilience, and transmission pathways of viruses. The people affected are everyone who eats, but the burden falls most heavily on the very young, the elderly, the immunocompromised, and those in regions with less robust food safety infrastructure.
The path forward requires a layered approach built on awareness, adaptation, and investment. For consumers, the message is to double down on the basics: meticulous handwashing, careful washing of produce, and avoiding high-risk items like raw shellfish if you are in a vulnerable group. For the food industry, it means integrating viral risk into every step of the supply chain, from implementing stricter worker health policies and hygiene training on farms to exploring new processing technologies that can inactivate viruses without compromising food quality. For scientists and regulators, the urgent tasks are to improve and standardize methods for detecting infectious viruses in food, to better understand how climate change and global trade influence viral spread, and to support the development of vaccines for other foodborne viruses.
The era of viewing foodborne illness solely through a bacterial lens is over. The viral challenge is complex and persistent, but by recognizing its distinct nature and mobilizing our defenses accordingly—from the simplicity of soap and water to the complexity of global surveillance networks—we can build a more resilient food system for everyone.
