Common Food Safety Hazards – Viruses

Identifying Hazards is an important part of developing your HACCP System. The information here assists with Principle 1 requirement to Conduct a hazard analysis and identify potential hazards. See our article HACCP 7 principles explained – How to implement a HACCP System based on new CODEX HACCP Principles and Decision Tree for more details.

The Main viruses associated with Food, Sources and Control Measures are summarized below

Viruses in General

Foodborne viruses are unable to multiply outside of a living host and therefore the virus must remain viable in contaminated food and be able to survive the stresses associated with the food environment until the food is consumed. Foodborne viruses are commonly transmitted by the fecal-oral route with the primary infection occurring in the gastrointestinal tract.

Unlike bacteria, viruses do not replicate in food and so viruses do not cause deterioration of the product or the organoleptic properties of the food. This makes contamination with viruses impossible to detect without analytical methods such as PCR or ELISA.

High numbers of viral particles are shed in the vomit and stools of infected persons, often exceeding a million per gram but less than 100 are needed to cause infection.

Joint FAO/WHO Expert Meeting on Microbiological Risk Assessment (JEMRA) has reported that Norovirus was considered to pose the greatest burden to public health. Next on the list were Hepatitis A virus and Hepatitis E virus. Other viruses transmitted through food with lower impact included Rotavirus, Sapovirus, enterovirus, Astrovirus and enteric Adenovirus.

Norovirus

Norovirus is the leading cause of foodborne illness outbreaks in the United States causing about half of all outbreaks of food-related illness. Norovirus is highly contagious, it only takes small number of the virus to contaminate food and then causes gastroenteritis, an inflammation of the stomach and intestines. Common symptoms include nausea, stomach pain, watery diarrhea, and sometimes a mild fever and body aches, which typically appear 12 to 48 hours after exposure and last for 1 to 3 days. Norovirus spreads through contaminated food, water, surfaces, or direct contact with an infected person. Most reported norovirus outbreaks are caused by people who touch or prepare food when they are sick, or sometimes by food that comes from contaminated water.

Foods commonly associated with Norovirus outbreaks include leafy greens, fresh fruits, and shellfish (especially raw oysters), often because they are handled directly by infected people or contaminated during preparation or from contaminated water. Other foods, particularly those that are raw or ready-to-eat like salads and sandwiches, are also high-risk.

Preventing norovirus in food production involves strict hygiene and safety protocols, including thorough handwashing, preventing bare-hand contact with ready-to-eat foods, washing fruits and vegetables and cook seafood well excluding sick employees, and using proper cleaning and sanitizing methods.

Norovirus & Hepatitis A are a Risk in berries, pomegranates (the arils), and any fresh, refrigerated, or frozen products containing berries or pomegranate generally

Good Hygienic Practices and exclusion of food handlers that are carriers or infected can reduce the potential for transfer of pathogens including Hepatitis A, and Norovirus.

Hepatitis A virus

Hepatitis A is a food safety hazard transmitted through the fecal-oral route, it spreads when an infected person prepares food or water without following strict hygienic protocols thus contaminating the food which is then consumed by others. Symptoms of foodborne hepatitis, most commonly hepatitis A, include fever, fatigue, nausea, vomiting, abdominal pain, loss of appetite, and dark urine. Jaundice (yellowing of the skin and eyes), pale stools, and joint pain can also occur. These symptoms generally appear 2 to 6 weeks after infection and can last for several months. Foods and drinks contaminated with the hepatitis A virus are often raw or undercooked items but also include other potential sources including food prepared by an infected person with poor hygiene, and ready-to-eat items like salads or sandwiches that have been cross-contaminated.

Contaminated foods often include raw or undercooked shellfish, poorly washed fruits and vegetables, and ready-to-eat cold foods that may be subject to cross-contamination. Contaminated water and ice can also be sources of the virus, this is usually caused by poor hygienic practices.

Prevention of Norovirus infections relies on good personal hygiene (especially handwashing), thorough cooking and careful food handling to prevent cross-contamination between raw and cooked foods.

Rotavirus

Rotavirus is highly contagious and is transmitted by the fecal–oral route. It infects and damages the cells that line the small intestine and causes gastroenteritis and often called ‘stomach flu’ despite but has no relation to influenza. Rotaviruses are the most common cause of diarrheal disease among infants and young children with most children in the world being infected with a rotavirus at least once by the age of five. This is because the primary mode of transmission for rotavirus is person-to-person spread. The feces of an infected person can contain more than 10 trillion infectious particles per gram and less than 100 of these are required to cause an infection in another person. Immunity normally develops with each infection, so subsequent infections are less severe and adults are rarely affected.

Rotavirus outbreaks have included fresh salad sandwiches from catering outlets.

Other implicated dishes included spicy seafood salad, shrimp in sauce, roast duck with vegetables and water from a cooler. Contaminated water and infected food handlers were probable sources of cross-contamination.

Note that sanitary measures that are considered adequate for eliminating bacteria and parasites seem to be less effective in control of rotavirus, as the incidence of rotavirus infection in countries with high and low health standards is similar.

Other Viruses

Data for outbreaks between 2009–2018 shows that 4 Adenovirus, 10 Astrovirus and 107 Sapovirus gastroenteritis outbreaks were reported to the US National Outbreak Reporting System. Most were attributable to person-to-person transmission in long-term care facilities, daycares, and schools. Investigations of norovirus-negative gastroenteritis outbreaks should include testing for these viruses.