Foodborne Microbial Hazards (including human enteric virus and foodborne parasite)
Foodborne microbial hazards include (but are not limited to) pathogenic bacteria, viruses, algae, protozoa, fungi, parasites, prions, toxins and other harmful metabolites of microbial origin (FAO and WHO, 2007).
A human enteric virus is a virus that replicates in the gastro-intestinal tract or in the liver and is excreted in faeces and/or vomitus from humans. It is transmitted mainly by the faecal-oral route and is infectious to humans (FAO and WHO, 2012).
A foodborne parasite is any parasite that can be transmitted to humans by ingesting food (FAO and WHO, 2016).
Primary reference(s)
FAO and WHO, 2007. Principles and Guidelines for the Conduct of Microbiological Risk Management (MRM). CXG63 -2007. Codex Alimentarius. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 21 October 2020.
FAO and WHO, 2012. Guidelines on the Application of General Principles of Food Hygiene to the Control of Viruses in Food. CXG 79-2012. Codex Alimentarius. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 21 October 2020.
FAO and WHO, 2016. Guidelines on the Application of General Principles of Food Hygiene to the Control of Parasites. Accessed 21 October 2020.
Additional scientific description
Foodborne diseases caused by foodborne microbial hazards are an important cause of morbidity and mortality, and a significant impediment to socioeconomic development worldwide. The symptoms of foodborne diseases range from mild and self-limiting (nausea, vomiting, diarrhoea) to debilitating and life-threatening (such as kidney and liver failure, brain and neural disorders, paralysis and potentially cancers), leading to long periods of absenteeism and premature death (WHO, 2015).
Human enteric virus refers to viruses that are very small microorganisms, ranging from 0.02 to 0.4 mm in diameter, whereas bacteria generally range in size from 0.5 to 5 mm. In addition to size, other (structural and biological) properties of viruses may also vary greatly, both among viruses and between viruses and bacteria. In contrast to bacteria, which are free living, viruses use the host cells to replicate. Viruses are diverse; for example, the virus genome can be DNA or RNA, in double- or single-stranded form. The virus particle can vary from a relatively simple structure consisting of a non-enveloped genome with a single protein coat, as is the case for most foodborne viruses, to a complex structure consisting of a segmented genome, encapsulated in a complex protein capsid and enveloped by a membrane. The structure of the virus particle is linked to the environmental resistance of the virus, with the more complex structure particles being less resistant (FAO and WHO, 2008).
Foodborne parasites are a major public health concern worldwide, particularly in areas with poor sanitary facilities and in populations that traditionally consume raw and undercooked food dishes. Infections may have prolonged, severe, and sometimes fatal outcomes, and result in considerable hardship in terms of food safety, food security, quality of life, and negative impacts on livelihood (FAO and WHO, 2016). Metrics and numeric limits The World Health Organization (WHO) reports that each year worldwide, unsafe food causes 600 million cases of foodborne diseases and 420,000 deaths. 30% of foodborne deaths occur among children under 5 years of age. The WHO estimated that 33 million years of healthy lives are lost due to eating unsafe food globally each year, and that this number is likely to be an underestimate (WHO, no date, 2015).
Metrics and numeric limits
The World Health Organization (WHO) reports that each year worldwide, unsafe food causes 600 million cases of foodborne diseases and 420,000 deaths. 30% of foodborne deaths occur among children under 5 years of age. The WHO estimated that 33 million years of healthy lives are lost due to eating unsafe food globally each year, and that this number is likely to be an underestimate (WHO, no date, 2015).
Key relevant UN convention / multilateral treaty
The Joint Food and Agriculture Organization of the United Nations (FAO) and WHO Food Standards Program (Codex Alimentarius Commission) for the establishment of food safety standards, such as maximum levels for food additives (quantitative levels above which there is a risk for consumer’s health) (FAO and WHO, no date).
The WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) (WTO, no date).
Examples of drivers, outcomes and risk management
Foodborne microbial hazards: Diseases caused by foodborne microbial hazards constitute a world-wide public health concern. During recent decades, the incidence of foodborne diseases has increased in many parts of the world. Foodborne threats occur for a number of reasons. These include: microbial adaptation; changes in the food production systems, including new feeding practices and changes in animal husbandry, agronomic process and food technology; increase in international trade, susceptible populations and travel; change in lifestyle and consumers demands; and changes in human demographics and behaviour. The globalisation of food markets has increased the challenge to manage these risks (FAO and WHO, 2007).
The WHO Foodborne Disease Burden Epidemiology Reference Group (FERG), provides the estimates of global foodborne disease incidence, mortality, and disease burden in terms of Disability Adjusted Life Years (DALYs). For the global estimates, 31 foodborne hazards causing 32 diseases are included: 11 diarrhoeal disease agents (1 virus, 7 bacteria, 3 protozoa), 7 invasive infectious disease agents (1 virus, 5 bacteria, 1 protozoon), 10 helminths and 3 chemicals. The most frequent causes of foodborne illness were diarrhoeal disease agents, particularly norovirus and Campylobacter spp. Foodborne diarrhoeal disease agents caused 230,000 deaths, particularly non-typhoidal Salmonella enterica (WHO, 2015).
Foodborne parasites: Foodborne parasites can be transmitted by ingesting fresh or processed foods that have been contaminated with the transmission stages (spores, cysts, oocysts, ova, larval and encysted stages) via the environment; by animals (often from their faeces); or by people (often due to inadequate hygiene). Foodborne parasites can also be transmitted through the consumption of raw and under-cooked or poorly processed meat and offal from domesticated animals, wild game and fish containing infective tissue stages. Despite the fact that the parasite does not replicate outside a live host, food processing techniques in common use can artificially amplify the quantity of contaminated food that reaches the consumer, increasing the number of human cases (e.g., sausage made from meats of different origin) (FAO and WHO, 2012).
The WHO FERG assessed data for the global burden of human foodborne trematodiasis in 2005, and estimated that 56.2 million people were infected by foodborne trematodes, of which 7.8 million suffered from severe sequelae and 7158 died worldwide (FAO and WHO, 2014).
Control of foodborne parasites can be achieved through the prevention of infection of farmed food animals with infective stages, the prevention of contamination of fresh and processed foods with infective stages, and/or the inactivation of parasites in or on foods during processing. Education and awareness-raising are important components of consumer protection from foodborne parasitic diseases and, in many cases, may be the only feasible option available (FAO and WHO, 2014).
Human enteric viruses: Humans become infected with enteric viruses following the ingestion of viruses present in faecally contaminated foods. The viruses enter the gastrointestinal tract, surviving the acidic conditions in the gut, and initiate an infection. Consequently, major foodborne viral disease outbreaks are caused by viruses from humans that are excreted in high numbers in human faeces. Another important factor affecting foodborne transmission is the stability of viruses outside the host. There is considerable potential for food contamination along the food chain continuum. For example, various reports have clearly provided strong evidence of ‘food handler’ transmission for some specific virus. A separate category is the animal viruses that are able to cause illness in humans. The viruses of potential risk to human health may enter the food chain through animal products, as well as when virus-laden animal manure contaminates food (FAO and WHO, 2012).
Estimates of the proportion of viral illness attributed to food are in the range of a few percent (around 5%) for Hepatitis A virus to 12–47% for Norovirus. This translates to estimated numbers of foodborne viral illness cases ranging from approximately 13,000 per million to 30,000 per million persons. Telephone surveys in the USA and Australia have also shown that such illness is common. No such data are available from developing countries but reports from the literature suggest that foodborne viral illness occurs worldwide (FAO and WHO, 2008).
Control of human enteric viruses such as Norovirus and Hepatitis A virus in food will typically require a stringent application of hygiene control systems, which could be referred to as, for example, Good Hygienic Practices (GHPs) and sanitation standard operation procedures (SSOPs). These prerequisite programmes, together with validated interventions, for example, as part of a hazard analysis and critical control point (HACCP)-based system, provide a framework for the control of enteric viruses (FAO and WHO, 2008).
References
FAO and WHO, no date. About Codex Alimentarius. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 19 September 2020.
FAO and WHO, 2007. Principles and Guidelines for the Conduct of Microbiological Risk Management (MRM). CXG63 -2007. Codex Alimentarius. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 21 October 2020.
FAO and WHO, 2008. Viruses in Food: Scientific Advice to Support Risk Management Activities. Microbial Risk Assessment Series 13. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 22 October 2020.
FAO and WHO, 2012. Guidelines on the Application of General Principles of Food Hygiene to the Control of Viruses in Food. CXG 79-2012. Codex Alimentarius. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 21 October 2020.
FAO and WHO, 2014. Multicriteria-based Ranking for Risk Management of Food-borne Parasites. Report of a Joint FAO/WHO Expert Meeting, 3–7 September 2012. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 22 October 2020.
FAO and WHO, 2016. Guidelines on the Application of General Principles of Food Hygiene to the Control of Parasites. CXG 88-2016. Codex Alimentarius. Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO). Accessed 21 October 2020.
WHO, no date. Estimating the Burden of Foodborne Diseases. World Health Organization (WHO). Accessed 22 October 2020.
WHO, 2015. WHO Estimates of the Global Burden of Foodborne Diseases. World Health Organization (WHO). Accessed 21 October 2020.
WTO, no date. The WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement). World Trade Organization (WTO). Accessed 3 October 2020.