Microbiological Hazards in the Food industry

Microbiological Hazards in the Food industry

 

Biological Hazard

A biological hazard, or bio-hazard, is a biological substance that poses a threat to the health of living organisms, primarily humans. This could include a sample of a microorganism, virus or toxin that can adversely affect human health.

Most common Microbiological Hazards in the Food industry

Pathogenic Bacteria: Bacillus cereus 

Bacillus cereus (B. cereus) is a Gram-positive, facultative anaerobic, endospore forming, large rod and has colonial morphology of about 2-7 mm in diameter, with a white granular texture.

The optimal growth temperature is 28°C to 35°C, with a minimum growth temperature of 4°C and a maximum of 48°C. Growth can occur in pH ranges from 4.9 to 9.

 

Pathogenicity: It causes two kinds of food borne disease:

1. An intoxication due to a toxin preformed in the food
2. An infection due to the ingestion of cells which produce enterotoxins in the small intestine.

Sources: Widespread in the environment being found in soil, water, air and vegetable matter.

 Rice products, pasta, vegetables, herbs, spices, milk and meat.

Illness, Symptoms and Complications:

B.cereus food poisoning is caused by toxins produced during the growth of the bacteria (emetic toxin (ETE)) and three different enterotoxins: Hemolysin (HBL), Nhe, and EntK. These toxins cause two distinctly different forms of food poisoning – the emetic/vomiting type or diarrhoeal type. Symptoms usually last around 24 hours. EntK ( Not involved in food poisoning).

Emetic type symptoms include nausea, vomiting and abdominal cramps.

Diarrhoeal type symptoms include watery diarrhoea, abdominal cramps and pain with occasional nausea and vomiting.

Although both forms are self-limiting more severe cases have been reported which included complications such as pyogenic infections, gangrene, septic meningitis, lung abscesses and infant death.

Controls to reduce the risk:

Foods should be cooked to a core temperature of 75°C (167°F) e.g. 70°C (158°F) for 2 minutes which will destroy the cells however in order to prevent the spores germinating it is essential that rapid cooling takes place. It may be beneficial to implement or install rapid chilling equipment to speed up the cooling process.

Hot food should be maintained at a temperature greater than or equal to 63°C (145.4°F) and chilled food should ideally be maintained at a temperature less than or equal to 4°C (39.2°F).

 

Pathogenic Bacteria : Staphylococcus Aureus

 

Characteristics: Staphylococcal species are Gram-positive, nonmotile, catalase-positive, small, spherical bacteria (cocci), which, on microscopic examination, appear in pairs, short chains, or bunched in grape-like clusters. S. aureus growth, in general, ranges from 7°C - 47.8°C, with 35°C being the optimum temperature for growth. The growth pH range is between 4.5 and 9.3, with an optimum from 7.0 - 7.5.

 

Pathogenicity: Staphylococcus aureus is found in foods and can make toxins (enterotoxins) that might not be destroyed by cooking, although the bacterium itself can be destroyed by heat. Staphylococcal enterotoxins are stable in the gastrointestinal tract and indirectly stimulate the emetic reflex centre by way of undetermined molecular events. It is thought that the vagus nerve is involved in the sequence of events that produce the emetic response.

Sources: It is very common in the environment and can be found in soil, water and air. It can live in humans and animals, approximately 50% of humans are carriers of this organism and food handlers are frequently implicated in the transmission of this pathogen to food. Some food sources include milk and milk-based products, cream, and cream-filled pastries and butter. Ham, other cured meats such as corned beef, bacon and sandwich.

Infectious Dose: The intoxication dose of Staphylococcus Enterotoxin is less than 1.0 microgram. This toxin level is reached when S. aureus populations exceed 100,000 organisms/g in food. In highly sensitive people, ingestion of 100 - 200ng of enterotoxin can cause symptoms.

Illness, Symptoms and Complications: Symptoms include nausea, abdominal cramping, vomiting and diarrhoea. In more severe cases headache, muscle cramping, dehydration and low blood pressure occur. The illness is relatively mild and usually lasts from only a few hours to one day; however, in some instances, the illness is severe enough to require hospitalization. Death from food poisoning from Staphylococcus aureus is uncommon, however, deaths have occurred among the elderly, infants and severely debilitated people.

Controls to reduce the risk: Implementation of a food safety management system based on the principles of HACCP. This includes good process control, e.g. temperature control during cooking – sources report that the Staphylococcus Aureus enterotoxin will be inactivated during cooking of 100°C for 30 minutes. Although they are lower water activity foods, those with high salt such as ham may need a longer cooking time. It is also important to store foods correctly e.g. refrigeration of high-risk foods.

 

Pathogenic Bacteria: Listeria monocytogenes

Characteristics: Listeria monocytogenes is a Gram-positive, rod-shaped, facultative bacterium, motile by means of flagella typically measuring 0.5 to 2μm long and 0.5μm in diameter. It has the ability to grow at low temperatures, a range of pH values (between 4.3 and 9.6), and can reproduce at temperatures between 1 and 45°C.

Not only can it survive at 1°C, unlike many other pathogens but it can also grow in these conditions so it is known as a psychrophile. It is also notable for its persistence in food-manufacturing environment.

Pathogenicity: Listeria monocytogenes is the bacteria that is the principal cause of listeriosis in humans. It was first described as a human pathogen in the 1920s.

The main target populations for Listeriosis are pregnant women/foetuses/neonates - perinatal and neonatal infections; persons immunocompromised by, for example, corticosteroids, anticancer drugs, graft suppression therapy, AIDS, cancer patients, particularly leukemic; the elderly.

Sources (Including High - Risk food groups): Many foods have been associated with Listeria monocytogenes. Examples include raw milk, inadequately pasteurized milk, chocolate milk, cheeses (particularly soft cheeses), soft serve ice cream, pâté, raw vegetables, raw poultry and meats (all types).

It is also found widely in the environment, soil, manure, decaying vegetable matter, silage, water and animal feed. Another major source is the food manufacturing environment especially on floors and drains.

Illness, Symptoms and Complications: It can cause 2 forms of disease. One can range from mild symptoms to intense symptoms of diarrhoea, nausea, vomiting, aches, fever and usually will go usually away by itself.

The other is a deadlier form which can occur when the infection spreads through the bloodstream and can result in meningitis and blood poisoning.

The duration of symptoms generally depends on the health status of the infected person and can last from days to several weeks.

In pregnant women, Listeriosis occurs mostly during the third trimester, and is characterised by a “flu like” illness with symptoms such as fever, chills, malaise, arthralgia, back pain, and diarrhoea. Intrauterine infection of the foetus can lead to foetal death, spontaneous abortion, premature delivery, or the birth of a foetus that dies shortly after birth.

Controls to reduce the risk:

The design and layout of floors and drainage systems is particularly important as floors and drains have been confirmed as a source of Listeria monocytogenes.

Where feasible, food processors should incorporate a listericidal processing step (e.g. cooking meat products to 70°C for two minutes) into the production of RTE and other at risk foods. Thermal processing steps such as cooking and pasteurisation are very effective in reducing numbers of Listeria monocytogenes. In some foods, a single intrinsic or extrinsic variable (e.g. pH, Temperature) may be used as a listericidal step.

 

Pathogenic Bacteria: Clostridium perfringens

Characteristics: Clostridium perfringens is an anaerobic (but aerotolerant) Gram-positive, spore-forming rod that produces enterotoxin. There are different strains (types A-E), most cases of food poisoning are caused by type A and sometimes type C. Not all strains are enterotoxin producers.

It can grow between temperatures of 15-55°C with the optimum being between 43-47°C (109.4-116.6°F). The optimum growth pH is 6.0 – 7.0.

 

Pathogenicity: The enterotoxins are produced when vegetative cells of the bacterium start to multiply in the human intestine and sporulate. During the sporulation the organism also releases the enterotoxin that causes the symptoms.

Sources: Type A is widely distributed in the environment in soil, vegetation and intestinal tracts of animals.

Food sources include cooked meats especially beef and poultry products. Meat containing products such as stews, rolled meat, meat pies and gravies.

Can also be found on vegetable products, including spices and herbs.

Illness, Symptoms and Complications: Foodborne illness caused by Clostridium perfringens can take two forms.

Gastroenteritis form: Symptoms include, abdominal cramps and watery diarrhoea. It is generally self-limiting depending on the strain, in some cases it can lead to more severe gastroenteritis which can lead to damage of the small intestine.

Enteritis necroticans (pig-bel disease): This is much more severe and fatal, but it is rare. Symptoms include pain and gassy bloating in the abdomen, diarrhoea and vomiting.

Controls to reduce the risk:

Heat Treatment

Cook foods until core temperature of 75°C (176°F) and serve immediately or store above 63°C (145.4°F). This will inactivate the vegetative cells however cooling is required to prevent spore germination.

Cooling

Rapid cooling of high risk product after cooking especially through the temperature of 55-15°C (131-59°F) followed by storage at a temperature of below 4°C (39.2°F).

 

Pathogenic Bacteria: Clostridium botulinum

Characteristics: Clostridium botulinum is an anaerobic, gram-positive, spore-forming bacterium that produces a potent neurotoxin. The spores are heat-resistant and can survive in foods that are incorrectly or minimally processed. It can grow between a temperature of 3 to 50°C and a pH of 4.6 – 9.0.

There are 7 distinct forms of botulinum toxin, types A–G. Four of these (types A, B, E and rarely F) cause human botulism. Types C, D and E cause illness in other mammals, birds and fish.

 

Pathogenicity: Botulism is caused by a neurotoxin formed during the growth of Clostridium botulinum. This neurotoxin binds to the neuromuscular junction and blocks excitatory synaptic transmission by inhibiting acetylcholine release causing (flaccid) paralysis and sometimes fatal respiratory failure.

Foodborne botulism, caused by consumption of improperly processed food, is a rare but potentially fatal disease if not diagnosed rapidly and treated with antitoxin.

Sources (Including High - Risk food groups): Widley distributed in nature with it being found in soil and marine environments as well as the intestinal tracts of fish and mammals.

Common food vehicles include low-acid processed foods, canned products, garlic oil, smoked fish or other marine products especially those packed in vacuum packs.

llness, Symptoms and Complications: Initial symptoms include double vision, blurred vision, slurred speech, vertigo, trouble swallowing and muscle weakness.

If the disease is not treated symptoms may progress to paralysis of the arms, legs, trunk and respiratory muscles. Patients with severe cases that involve paralysis of the respiratory muscles may need mechanical ventilation and intensive care for weeks or months.

Controls to reduce the risk:

Sources recommend that the following controlling factors should be used singly or in combination to prevent growth and toxin production in chilled foods with a shelf-life of more than ten days.

A heat treatment of 90ºC for ten minutes or equivalent lethality, a pH of 5 or less throughout the food and throughout all components of complex foods.

A minimum salt level of 3.5% in the aqueous phase throughout the food and throughout all components of complex foods, a water activity (aw) of 0.97 or less throughout the food and throughout all components of complex foods.

Safety of canned food is based on the destruction of the spores i.e 121°C for a minimum of 3 minutes also known as (Botulinum Cook).

 

Pathogenic Bacteria : Escherichia.coli O157

 

Characteristics: Escherichia coli O157 is gram negative, rod shaped, non-spore forming bacteria belonging to the family, Enterobacteriacae. It is a harmful bacterium that is particularly dangerous because it has the ability to survive during refrigeration and freezing and has been shown to be tolerant of acid, salt and dry conditions. It can grow between temperature of 7-46°C and at a pH as low as 4.4.

Pathogenicity: Escherichia coli 0157 is commonly found in the lower intestine of warm-blooded organisms. It can produce a toxin (Shiga toxin) which can cause serious illness. It can affect all ages, however there have been higher mortality rates occur in the elderly and young.

Infectious Dose: The infective dose of Escherichia.coli O157 is estimated to be very low, in the range of 10 to 100 cells.

Sources (Including High - Risk food groups): Ground meats, unpasteurised milk, unpasteurised fruit juice, lettuce, spinach and sprouts. Soil where fresh produce grows can become contaminated so root crops and leafy vegetables are a potential source. Also, a major source is animals and their environment, in particular cattle.

Waterborne transmission has been reported both from contaminated drinking water and from recreational waters. Person to person contact is also a mode of transmission through the oral-faecal route. An asymptomatic carrier state has been reported, where individuals show no clinical signs of disease but are capable of infecting others.

Illness, Symptoms, and Complications: Bloody diarrhoea (haemorrhagic colitis), severe cramping, nausea and vomiting. In severe cases this may progress to life-threatening complications as (HUS) where red blood cells are destroyed causing kidney injury. This can result in the person requiring intensive care, kidney dialysis, and transfusions. It can also lead to Thrombotic thrombocytopenic purpura (TTP). About 3% -7% of the haemorrhagic colitis cases progress to HUS or TTP.

Controls to reduce the risk: The control starts on the farm with the implementation of good agricultural practice which can help reduce the shedding of Escherichia.coli 0157 from animals such as cattle.

The prevention also requires controls during manufacturing and preparation of foods such as preventing cross-contamination of foods and cooking food so that the core reaches at least 70°C for 2 minutes. Water supplied to food businesses, including private supplies, must meet potable water standards.

Pathogenic Bacteria :: Salmonella

Characteristics: Salmonella is a motile, non-spore forming, Gram-negative, rod-shaped bacterium of the family Enterobacteriaceae that is approximately 0.7-1.5 by 2.0-5.0μm in size. It has the ability to grow between a pH of 3.7-9.5 and a temperature of 7-48°C.

Pathogenicity: Salmonellosis is a zoonotic infection which means it can be transmitted to humans from animals. Salmonella can cause two types of illness

(1) Non-typhoidal salmonellosis and

(2) Typhoid fever.

The symptoms of nontyphoidal salmonellosis can be quite unpleasant, but this illness is generally self-limiting among healthy people with an intact immune system (although it can cause life-threatening illness even in healthy people).

Typhoid fever is more serious and has a higher mortality rate than nontyphoidal salmonellosis. Vulnerable people would be the young, elderly and those suffering from chronic illness or disease such as HIV.

Sources (Including High - Risk food groups): Raw meats, poultry, eggs, unpasteurised milk and dairy products, seafood, fresh produce (including seed sprouts) and spices. Salmonella is also widely dispersed in nature and the environment. It can colonize in the intestinal tracts of vertebrates, including livestock, wildlife, domestic pets, and humans.

Illness, Symptoms, and Complications: Salmonellosis symptoms include nausea, vomiting, abdominal cramps, diarrhoea, fever and headache and can last between 4-7 days with acute symptoms lasting 1-2 days depending on the host factors and the dose ingested.

Nontyphoidal Salmonella can sometimes escape from the gastrointestinal tract into the body and cause blood poisoning (septicemia) or infect the blood, internal organs, and/or joints (bacteremia).

Typhoid fever which symptoms include high fever, lethargy, gastrointestinal symptoms including abdominal pain, diarrhoea or constipation, achiness, loss of appetite. Sometimes a rash of flat rose-coloured spots can occur. Septicemia, with colonization of other tissues and organs, may lead to endocarditis. Septic arthritis may occur, in which the infection directly affects the joints and may be difficult to treat. Chronic infection of the gallbladder may occur, which may cause the infected person to become a carrier.

Controls to reduce the risk: The control of Salmonella in food should start on the farm with the careful production of animal-derived raw materials such as eggs, poultry, pork and fresh produce. Suppliers should carefully source their ingredients and supplies from approved suppliers and in particular, purchase pasteurised products (such as milk or eggs). Salmonella can be effectively controlled by relatively mild heat processing (e.g pasteurisation) but it is essential that cross-contamination between food is avoided.

 

Pathogenic Bacteria : Shigella

Characteristics: Shigella species are gram-negative, non-spore forming, rod shaped bacteria.

They belong to the group Enterobacteriaceae and there are four different species which include

S. sonnei, S. dysenteriae, S. flexneri and S .boydii. They are non-motile, non-encapsulated, facultative anaerobes.

 

Pathogenicity: Pathogens that are ingested have the ability to survive gastric acidity and they

can cause illness by infecting the colonic mucosa. They can then multiply in the colonic epithelial cells and can spread laterally to adjacent cells.

The organisms can spread through the faecal-oral route e.g. either through the ingestion of

contaminated foods that have been washed or produced using faecal contaminated water or

handled with poor hygiene.

Sources (Including High - Risk food groups): Humans are the main source for Shigella, and it is known to be very contagious. Almost any food can become contaminated with faecal material from infected individuals e.g. eating food that was prepared or cooked by an individual who is ill with Shigella. Food can also become contaminated with sewage contaminated water.

Foods that are handled a lot during manufacturing and are not later cooked e.g. Ready to Eat

foods such as salads and sandwiches are of specific risk as they can become contaminated from infected food handlers and with no subsequent step such as cooking.

Illness, Symptoms and Complications: Abdominal pain, cramps, fatigue, fever and diarrhoea which can sometimes be bloody, are the most common symptoms of the illness. Due to diarrhoea it can also lead to dehydration.

Longer-term complications can occur such as reactive arthritis and haemolytic uraemic syndrome.

Controls to reduce the risk:

Can be inactivated by heat treatment at temperatures at 65°C/149°F and above.

 

Pathogenic Bacteria :: Pseudomonas aeruginosa

 

Characteristics: Pseudomonas aeruginosa is a gram negative, non-spore forming, strictly aerobic bacterium. They are sensitive to heat and are readily inactivated by normal cooking processes.

They are sensitive to desiccation and are not tolerant of acid pH.

They are notable for their relative resistance to disinfectants and they can form biofilms on surfaces, making them very difficult to remove.

 

Pathogenicity: Pseudomonads are ubiquitous and are usually transmitted through contaminated water. Can invade the tissue, cause infection and bacteraemia.

Sources (Including High - Risk food groups): Commonly present in environmental sources such as soil and water. It is thought that it can be found on fruits, vegetables and thought to be found in meat. However, the most concern is in water supplies and bottled water.

Illness, Symptoms and Complications:

Can cause urinary tract infections, soft tissue infections, bone and joint infections and gastrointestinal infections.

Serious Pseudomonas infections usually occur in people in the hospital and/or with weakened immune systems. Infections of the blood, pneumonia, and infections following surgery can lead to severe illness and death in these people.

Controls to reduce the risk:

Mild heat processes can readily inactivate the microorganism.

 

Pathogenic Bacteria: Campylobacter jejuni

Characteristics: Campylobacter jejuni (C. jejuni) is a nonsporeforming, gram-negative rod with a curved- to S-shaped morphology. It is 0.2-0.9 μm wide and 0.5-5 μm long, and moves by a corkscrew-like motion. It can grow between a temperature of 30 to 45°C with an optimum of 42°C and between a pH of 6.5 to 7.5.

 

Pathogenicity: C. jejuni cause infections by invading and colonizing the human gastrointestinal tract. Motility appears to be an important factor in the pathogenesis, enabling the bacterium to invade the human intestinal mucosa.

Sources (Including High - Risk food groups): Can be found in the intestinal tract of many warm-blooded animals such as poultry, cattle, sheep and pigs.

Major food sources linked to C. jejuni infections include improperly handled or undercooked poultry products, unpasteurised (“raw”) milk, cheese made from unpasteurised milk and contaminated water.

C. jejuni has been found in a variety of other foods such as vegetables and seafood. C. jejuni also occurs in non-chlorinated water, such as that found in ponds and streams.

Illness, Symptoms and Complications: Anyone can get sick from food contaminated with C. jejuni and it is generally self-limiting in healthy people. Younger children and those with weaker immune systems are at higher risk.

Symptoms include fever, diarrhoea, abdominal cramps, headache and muscle pain. Blood and mucus may be present in stools.

Long term complication includes autoimmune disorders such as Guillain-Barre syndrome (GBS) which is a severe nerve disorder and can lead to paralysis. Reactive Arthritis is another potential long-term complication.

C. jejuni bacteraemia may also affect pregnant women, leading to infection of the foetus, which can lead to miscarriage or stillbirth.

Controls to reduce the risk:

At abattoir and poultry plants, control measures should be implemented to prevent or control contamination of meat from the skin, hides or alimentary tract of infected animals.

Ensure that only drinking water is used in food preparation. Where water from private group schemes or private wells is used, it is essential that any disinfection/treatment systems are properly maintained.

Campylobacter is killed by heat, so cooking to 70°C for 2 minutes eliminates this bacterium.

 

Pathogenic Bacteria: Vibrio cholerae

Characteristics: V. cholerae is a highly motile, comma shaped, halophilic, gram-negative rod. Initial isolates are slightly curved, whereas they can appear as straight rods upon laboratory culturing. The bacterium has a flagellum at one cell pole as well as pili. The Vibrios tolerate alkaline media that kill most intestinal commensals, but they are sensitive to acid. V. cholerae is a facultative anaerobic, and can undergo respiratory and fermentative metabolism. It measures 0.3 micron in diameter and 1.3 micron in length with average swimming velocity of around 75.4 +/- 9.4 microns/sec.

Pathogenicity: V. cholerae secretes cholera toxin (CT), a protein that causes profuse, watery diarrhea (known as "rice-water stool").

Sources: The bacterium's natural habitat is brackish or saltwater where they attach themselves easily to the chitin-containing shells of crabs, shrimps, and other shellfish. Some strains of V. cholerae cause the disease cholera, which can be derived from the consumption of undercooked or raw marine life species. Contaminated water.

Illness, Symptoms and Complications: V. cholerae infects the intestine where it then causes diarrhea. Some symptoms include: watery diarrhea, vomiting, rapid heart rate, loss of skin elasticity, low blood pressure, thirst, and muscle cramps. This illness can get as serious as kidney failure and possible coma.

Controls to reduce the risk: Provision of safe water and sanitation is critical to prevent and control the transmission of cholera and other waterborne diseases.

This organism is heat sensitive, with a D-value of 2.65 minutes at 60°C

 

Pathogenic Virus: Hepatitis A

Characteristics: HAV is a member of the Picornaviridae family and Hepatovirus genus. It is an icosahedral, non-enveloped, positive-sense RNA virus and is 27-32 nm in diameter. Although HAV cannot grow in the environment, it can survive refrigeration and freezing for up to two years and is resistant to acid (pH 1 for 2 hours at room temperature). HAV has a higher resistance to many chemicals and drying than other enteroviruses.

 

Pathogenicity: HAV causes acute hepatitis and is not associated with chronic liver disease. Most individuals infected with HAV develop nonspecific constitutional signs and symptoms followed by gastrointestinal symptoms. The virus is primarily spread when an uninfected (and unvaccinated) person ingests food or water that is contaminated with the faeces of an infected person.

 

Sources: HAV is most commonly spread by direct person to person contact via the faecal-oral route. Food-borne outbreaks can often be traced back to an infected food handler or foods that have come into contact with faecally contaminated water. Food sources include water, shellfish (such as oysters, cockles and mussels) and milk. Fresh produce such as salads, fruit and vegetables are also sources. These are likely to be consumed raw or lightly cooked and can become contaminated with faecal matter at almost any point during growing, harvesting, transport and packing.

Illness, Symptoms and Complications: Symptoms usually include fever, nausea, vomiting, diarrhoea, fatigue, poor appetite, abdominal discomfort and often jaundice. The jaundice starts to occur generally 5-7 days after the onset of the gastrointestinal symptoms.

Controls to reduce the risk: Strategies to reduce the risk of food-borne outbreaks of Hepatitis A should focus on preventing foods from becoming contaminated. It is always important to make sure only approved suppliers are used when purchasing raw materials. It is also important that clean, treated water should be used for the irrigation, washing and processing of foods.

HAV is relatively heat resistant, however thorough cooking at a temperature of 85°C for 1 minute can inactivate the virus.

Pathogenic Virus: Norovirus

Characteristics: Noroviruses are a group of viruses belonging to the Norovirus genus and the Caliciviridae family. Based on the sequence of the major capsid protein, these viruses are further divided into 6 genogroups (GI-GVI), consisting of numerous genotypes. GI, GII and GIV are the only genogroups known to infect humans.

The virus is round, non-enveloped, single-stranded, positive-sense, polyadenylated RNA.

Pathogenicity: Noroviruses are environmentally hardy organisms that not only can be transmitted by food and water, but also can be easily transmitted through person to person contact and contact with environmental surfaces.

Norovirus infection causes acute gastroenteritis, characterized by rapid onset of symptoms. Up to 30% of infections are asymptomatic however, these individuals are able to transmit the virus.

Sources : Consumption of contaminated water or food. Also through the faecal/oral route.

Food vehicles can include shellfish, salad ingredients and fruit.

Illness, Symptoms and Complications: Typical symptoms are vomiting (often projectile), diarrhoea, abdominal pain, nausea, headache, stomach cramps and occasionally low-grade fever.

The severity of symptoms appears to be higher in hospitalized patients, immunocompromised people and elderly people.

Dehydration is the most common complication especially among the young, the elderly and patients with underlying medical conditions.

The illness usually lasts from 12 -60 hours although there have been reports symptoms have lasted for more than two weeks.

Controls to reduce the risk:

To reduce the risk of food-borne transmissions of noroviruses controls include, using only potable water for food processing. Only using approved suppliers and shellfish from approved harvesting waters.

Adequate cleaning of surfaces and equipment using approved detergents and sanitizers.

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