CAC/GL 79-2012 Guidelines on the Application of General Principles of Food Hygiene to the Control of Viruses in Food
INTRODUCTION
1. In recent years, viruses have been increasingly recognized as important causes of foodborne diseases. Viruses are microorganisms that differ in size, structure and biological characteristics from bacteria. Viruses are strictly host-dependent for their replication and have their own typical host range and cell preference (tropism). Viruses can be transmitted in different ways, e.g., via the respiratory or faecal-oral routes. Human viruses can be transmitted directly from person-to person, but also indirectly via virus-contaminated water, air, soil, surfaces or food. Some viruses (zoonotic viruses) are transmitted from animals to humans. Data from recent studies have shown that foodborne viral infections are very common in many parts of the world, despite the measures already in place mainly targeted at reducing bacterial contamination.
2. The human enteric viruses most frequently reported as involved in foodborne outbreaks are norovirus (NoV) and hepatitis A virus (HAV). Other viruses such as rotavirus, hepatitis E virus (HEV), astrovirus, Aichi virus, sapovirus, enterovirus, coronavirus, parvovirus and adenovirus can also be transmitted by food, and anecdotal evidence suggests the list of foodborne viruses may be even longer. Based on the symptoms of disease, these viruses can be grouped into those that cause gastroenteritis (e.g., NoV), enterically transmitted hepatitis (e.g., HAV, that replicates in the liver), and a third group which replicates in the human intestine, but only causes illness after they migrate to other organs such as the central nervous system (e.g., enterovirus). The major foodborne viruses are those that infect via the gastrointestinal tract and are excreted in faeces and/or vomit, and are infectious for humans when ingested via the oral route. Asymptomatic infections and shedding are common and have to be considered in food production.
3. Noteworthy aspects of foodborne viruses and the associated infections/illnesses that determine management strategies to be different from management strategies for bacterial pathogens:
