Selection of Cases and Attributes Plans
8.4 Categorizing Microbial Hazards According to Risk
8.4.3 Severe Hazards, Life Threatening
These microbial hazards can result in substantial chronic sequelae or the effects can be of long duration, can affect either the general population, or may be specific to populations at high risk. Factors influenc-ing the development of illness in high-risk populations include specific host susceptibility to infection such as listeriosis in pregnant women, cultural practices such as consumption of potentially hazardous foods unique to specific subpopulations, or to geographic influences such as fumonisin intoxication associated with regions in which moldy maize is consumed. About 5–10% of cases of acute infection due to E. coli O157:H7 go on to develop hemolytic uremic syndrome (HUS) and patients who develop HUS have a mortality rate of around 3–5%.
The major microbial pathogens and toxins associated with foods in relation to their impact to pub-lic health, their frequency of involvement in disease, the types of foods that have served as vehicles, and significant factors contributing to disease, are listed in Table 8.2. This table is not intended to be all-inclusive and no attempt has been made to arrange these pathogens and toxins according to fre-quency with which they cause outbreaks or cases of foodborne illness, because this varies with local-ity. Table 1.1 (Chap. 1) indicates whether microbiological testing of foods (e.g., at a port of entry) or other control measures have been instrumental in controlling the hazard and ensuring food safety.
Table 8.2 Ranking of foodborne pathogens or toxins into hazard groups (severity of threat to health)
Microorganism Frequency of involvement
in foodborne disease Examples of vehicles
associated with outbreaks Other factors contributing to significance
I. Moderate, not usually life-threatening; no sequelae; normally short duration; symptoms are self-limiting;
can be severe discomfort Bacteria
Arcobacter butzleri and A. cryaerophila
Low; the prevalence of Arcobacter infection may be underestimated and the exact routes of
transmission are unknown.
Contaminated foods of animal origin (particularly poultry and pork) and consumption of contaminated water are likely to be the most important transmission routes.
Patients can be asymptomatic.
Symptoms associated with acute watery diarrhea, sometimes being persistent or recurrent for greater than 2 weeks or even as long as 2 months. Antimicrobial therapies may be effective with resolution within few days.
Bacillus cereus (B.
cereus gastroenteritis) including emetic toxin
Common Fried and boiled rice;
reconstituted cereal products;
puddings, custards
Usually diarrhea and/or vomiting of short duration; death is rare
Campylobacter
jejuni a High; a leading cause of bacterial diarrheal illness in the US, often implicated with raw poultry.
Resident in the intestinal track, reported high contamination in raw poultry as well as with raw milk and untreated water.
Symptoms includes diarrhea, which may be watery or sticky, contain blood, lasting several days, but most are self-limiting.
(continued) 8.4 Categorizing Microbial Hazards According to Risk
172
Microorganism Frequency of involvement
in foodborne disease Examples of vehicles
associated with outbreaks Other factors contributing to significance
Clostridium perfringens type A (C. perfringens)a
High; the third most common foodborne disease in US and UK.
Spores of C. perfringens can withstand cooking
temperatures and grow with improper refrigeration.
Associated products include cooked, non-cured meats, poultry, and gravy.
Symptoms usually mild, but are more serious in elderly or debilitated persons; death is uncommon.
Enteropathogenic Escherichia coli (EPEC) a, and Enterotoxigenic E.
coli (ETEC) a
High; EPEC and ETEC are the leading bacterial cause of diarrhea in the developing world, as well as the most common cause of travelers’ diarrhea.
Foods handled by persons carrying EPEC or ETEC; foods contaminated with non-potable water.
Diarrhea remains a leading cause of death in children younger than 5 years globally, especially in the developing world. For the general population, diarrhea is short in duration.
Staphylococcal enterotoxins (S.
aureus)
(enterotoxicosis or food poisoning)
Medium; frequently found in the human respiratory tract and on the skin, some are pathogenic whilst others are capable of producing heat-stable enterotoxins.
Cooked foods handled by persons carrying S. aureus then temperature- abused; ham;
fermented sausages; cereal-filled pastries; cheese; milk, salads, peeled crustaceans, bivalve mollusk, and mushrooms.
Explosive vomiting and moderate diarrhea; symptoms usually resolve without treatment within 2 days of onset; death is rare.
Vibrio cholerae non O1 and non O139 (e.g., V.
cholera O75)
Low; sporadic; natural bacterial reservoir in sea and coastal waters, with seafood as vector for transmission for the disease.
Primary transmission through consumption of raw or undercooked seafood, particularly bivalve mollusks, cross-contaminated cooked crustaceans.
Mild diarrhea to severe watery diarrhea not typically associated with fever or bloody diarrhea.
Treatment primarily by rehydration, and antibiotic therapy.
Vibrio
parahaemolyticus (Vibrio
parahaemolyticus gastroenteritis)
Medium; common, natural bacterial reservoir in sea and coastal waters with seafood as vector for transmission for the disease.
Parasites Cryptosporidium parvuma
Medium; Cryptosporidium pose a risk to rural environments where water supplies are untreated and susceptible to contamination from agricultural animal waste/manure, animal wastewater, septic tank effluents and septage.
Untreated water, unpasteurized apple juice, contaminated produce, and unpasteurized milk.
Cryptosporidiosis is typically an acute, short- term infection, but can become severe in children and the immunocompromised.
Cyclospora cayetanensis
Medium; infection can occur by consuming food or water contaminated with the parasite. People living or traveling in countries where cyclosporiasis is endemic may be at increased risk for infection.
Humans are the only host with infection transmitted through the fecal-oral route. Foods associated include berries especially raspberries (fresh and frozen); lettuce; basil;
snow peas, cilantro, and water.
Gastroenteritis with a persistent watery diarrhea lasting over several days to weeks before self-limiting. Unless treated, illness may relapse with increase severity for
immunocompromised people.
Giadia lamblia Medium; common in developing countries, but low in developed countries.
Giardiasis is most frequently associated with the consumption of contaminated water.
Contaminated water, vegetables, and food contamination by infected or infested food handlers.
Infection can be asymptomatic.
Diarrhea within 1 week of cyst ingestion with illness lasting for 1–2 weeks, with some chronic cases lasting from months to years.
Table 8.2 (continued)
(continued) 8 Selection of Cases and Attributes Plans
173
Microorganism Frequency of involvement
in foodborne disease Examples of vehicles
associated with outbreaks Other factors contributing to significance
Toxoplasma gondii
a
Medium; infection (close to 30% of the world population may be infected with Toxoplasma) but with sporadic illnesses.
Undercooked, contaminated meat (especially pork, lamb, and venison) with cysts, any food or water contaminated with oocycsts, or through contacts with cat feces that contain Toxoplasma.
Although mild, flu-like symptoms occasionally occur during the first few weeks following exposure, infection are usually asymptomatic in healthy people.
Trichinella. spp. Medium; sporadic and occasional outbreaks. Most of the infections in Europe, with about half from Romania.
Pork (from domestic pigs and wild boars), horse meat, wild game meat.
Acute stage with general weakness, chills, headache, fever (up to 40 °C), excessive sweating and tachycardia followed by symmetrical eyelid and periocular oedema.
Viruses Caliciviridae, including norovirus and sapovirus
High: can be found in human and other animal host, with transmission generally by the fecal-oral route, but can also be transmitted via the respiratory route.
Faecally contaminated raw bivalve mollusks and transmission of food handled by infected persons, leafy vegetables, fruit (especially berries) and mollusks.
Commonly cause acute gastroenteritis which may include vomiting and diarrhea.
Symptoms emerge after an incubation time of 2 days and the symptoms only generally last for 3 days.
Hepatitis E virusa Low; found worldwide, but with the highest prevalence in East and South Asia and Sub-Saharan Africa and in developing countries.
Contaminated water; sporadic cases linked to raw or undercooked pig liver/
sausages.
Typical signs and symptoms of hepatitis include jaundice, loss of appetite, an enlarged, tender liver, abdominal pain and tenderness, nausea and vomiting as well as fever. In rare cases, acute hepatitis E can result in acute liver failure and death. Overall population mortality rates from hepatitis E range from 0.5% to 4.0%.
Others Biogenic amines (e.g., histamine)
Rare; histamine is produced and can accumulate when bacterial enzymes metabolize naturally occurring histidine in fish or in the fermentation of some food products.
Scombroid fish, fermented sausages and fermented fish meat and some cheeses.
May occur when fish is held at ambient or high temperatures or when fermented food products have availability of free amino acids, the presence of microorganisms producing biogenic amines enzymes.
II. Serious hazard; incapacitating but not life-threatening; sequelae infrequent; moderate duration Bacteria
Listeria monocytogenesa
Low; sporadic, making epidemiological links to food can be difficult. The capability for growth at low temperatures permits multiplication in refrigerated foods.
Soft and semi-soft cheeses, deli-meats, paté, smoked fish, fermented raw-meat sausages, produce (e.g., cantaloupe, cut celery, sprouts)
Its ability to grow at temperatures as low as 3 °C permits multiplication in refrigerated foods. Low numbers of L. monocytogenes are often consumed on a wide range of RTE foods.
Salmonella Enteritidis, Salmonella Typhimurium and other Salmonella serovarsa (salmonellosis)
High; widespread occurrence in animals, especially in poultry and swine and environmental sources including water, soil, insects, factory surfaces and food preparation surfaces.
Eggs; poultry; produce, dairy products; wide range of other foods, including low-moisture foods
Can be serious for young and elderly persons; cross-
contamination from raw meat and poultry; eggs and poultry meat can be internally contaminated during production; some serovars of Salmonella are highly virulent;
reactive arthritis occurs in 1–2% of cases (Reiter’s syndrome) Table 8.2 (continued)
(continued) 8.4 Categorizing Microbial Hazards According to Risk
174
Shigella flexneri, S. boydii, S.
sonnei (shigellosis) (non-dysentery)
Low; sporadic in industrialized countries, sometimes endemic in developing countries.
Fecally contaminated water and unsanitary handling by food handlers are the most common causes of contamination.
Foods subject to contamination includes salads, raw vegetables, milk and dairy products, and poultry.
Serious for young and elderly persons; secondary infections among contacts; sometimes low infectious dose, HUS occasionally.
Yersinia enterocolitica (pathogenic), Yersinia
pseudotuberculosis (yersiniosis)
Rare; sporadic, does not occur frequently, unless due to loss of food manufacturing controls.
Yersiniosis is most often acquired by eating contaminated food, especially raw or undercooked pork products. Drinking contaminated unpasteurized milk or untreated water can also transmit the infection.
Most infections occur in children less than 5 years of age, with symptoms of mild gastroenteritis; in older children symptoms are severe, presenting a pseudo appendicular syndrome; only certain serovars and strains of Y. enterocolitica are pathogenic; sequelae; arthritis can occur in genetically- predisposed persons that carry the human leucocyte antigen (HLA-B27).
III.A. Severe hazard for general population, life threatening or substantial chronic sequelae or long duration Bacteria
Botulinum neurotoxin (Clostridium botulinum, C.
butyricum, C. barati) (botulism)a
Rare; associated with inadequately processed, home- canned foods, but occasionally commercially produced foods have been involved.
Improperly processed canned or preserved low acid foods:
“home” cured meat products;
smoked fish, other marine products; foil wrapped baked potato in salad, garlic in oil, and carrot juice.
Rapid recognition and treatment essential for patient survival; substantial mortality
Brucella melitensis, B.
abortus, B. suis (brucellosis)
Low; transmission is by contact with infected animals or animal products contaminated with the bacteria (cattle, goats, pigs, and dogs, amongst others).
Common in endemic areas.
Raw milk and raw milk cheese, especially from goats and sheep.
Brucella function as facultative intracellular parasites, causing chronic disease, which usually persists for life.
Coxiella burnetii (Q fever)
Rare; Q fever is a worldwide disease with acute and chronic stages caused by the bacterium Coxiella burnetii. Cattle, sheep, and goats are the primary reservoirs.
Human infections mainly result from the inhalation of dust contaminated with bacteria from the placenta and birth fluids or faeces from infected animals, and consumption of unpasteurized milk. Other modes of transmission, such as through contaminated water or the faeces of infected arthropods are rare.
Most people with acute Q fever infection recover, although others may experience serious illness.
Pregnant women who are infected may be at risk for pre-term delivery or miscarriage. Chronic Q fever is a severe disease occurring in <5% of acutely infected patients.
(continued) Table 8.2 (continued)
Microorganism Frequency of involvement in foodborne disease
Examples of vehicles associated with
outbreaks Other factors contributing to significance
8 Selection of Cases and Attributes Plans
175
Enteroaggregative hemorrhagic E. coli (e.g., E. coli O104:H4) (hemorrhagic colitis and hemolytic uremic syndrome)
Low; emerging E. coli pathotype that is endemic in Central Africa, but can be sporadic in Europe and Asia.
One large outbreak, in Germany, was traced to raw sprouted seeds.
Very severe for children and elderly, severe complications including kidney failure and death, low infectious dose .
Enterohemorrhagic E.
coli (e.g., E. coli O157:H7, O26, O111) (hemorrhagic colitis and hemolytic uremic syndrome)
Medium; hemorrhagic colitis infections are not too common, but may not be reflective of the true frequencies, with undercooked or raw hamburger implicated in outbreaks.
Undercooked ground beef, unpasteurized apple juice, vegetable sprouts, leafy greens, venison, yoghurt, fermented sausage, untreated and recreational water, contact with farm animals.
Very severe for children and elderly, severe complications including kidney failure and death, low infectious dose, acid tolerance.
Mycobacterium bovis (tuberculosis)
Rare in developed countries, but common in developing countries where milk pasteurization or cattle examination are not routine.
M. bovis can cause tuberculosis in humans and other mammals.
Raw (unpasteurized) milk, raw milk cheeses.
Tuberculosis typically attacks the lungs, but can also affect other parts of the body. It is spread through the transmission of respiratory fluids through the air. If left untreated, may lead to high mortality.
Salmonella Typhi, S.
Paratyphi A, B (S.
Schotmulleri) and C (typhoid and paratyphoid fevers)
Medium, endemic in many parts of the world, occasionally epidemic.
Untreated water, raw milk, meat products, raw shellfish, and unpasteurized tempeh.
Prolonged medical care required, asymptomatic chronic carrier state commonly occurs Shigella dysenteriae I
(shigellosis)
Low; in developed countries. High; sporadic and endemic in developing countries where the spread is by contaminated water and food.
Fecally contaminated water and unsanitary handling by food handlers are the most common causes of contamination; salads, raw vegetables, and untreated water.
Severe dysentery due to potent Shiga toxin.
High mortality rate, especially among children, low infectious dose.
Vibrio cholerae O1 and O139 (cholera)
Medium; cholera is generally a disease spread by poor sanitation, resulting in contaminated water supplies, but may also be transmitted by shellfish harvested from nonpolluted waters. Sporadic; endemic;
sometimes epidemic
Raw seafood from polluted water; untreated water.
Substantial mortality among dehydrated, untreated persons; moderate symptoms with available rehydration treatment.
Parasites
Taenia saginata Medium: globally found to be most prevalently where cattle are raised and beef is consumed. Common in Africa, some parts of Eastern Europe, Southeast Asia, South Asia and Latin America.
Raw or undercooked beef or game meat containing live cysticerci.
Patients are either
asymptomatic or suffer from non-specific symptoms like vomiting, nausea, epigastric pain, diarrhoea and weight loss, and in rare cases, ileus, ancreatitis, cholecystitis, cholangitis and an acute cholangitis.
Taenia solium (Cysticercosis)
Medium; an intestinal zoonotic parasite found throughout the world, and is most prevalent in countries where pork is eaten.
Raw or undercooked pork for adult tapeworm and fresh produce for cysticerci, the larval form of T. solium,
(continued) Table 8.2 (continued)
Microorganism Frequency of involvement
in foodborne disease Examples of vehicles
associated with outbreaks Other factors contributing to significance
8.4 Categorizing Microbial Hazards According to Risk
176
Others
Abnormal Prions or Protease Resistant protein (PrPSc)
Rare; sporadic diseases such as variant Creuzefeldt- Jacob disease.
Bovine offal of infected animals, where prions are accumulated. Those organs are target of regulation at slaughter as Specified Risk Material (SRM) (brain, spinal cord, intestines, tonsils, thymus, spleen).
Severe central nervous system disorder resulting in death; no treatment or cure.
III.B. Severe hazard for vulnerable populations, life-threatening or substantial chronic sequelae or long duration
Bacteria Campylobacter jejuni serovar O19 and other serotypes associated with GBS (Guillain- Barré Syndrome) a
Low, infection with Campylobacter jejuni has emerged as one of the most common antecedent events associated with Guillain-Barré Syndrome.
Poultry, water, and raw milk.
Guillain-Barré Syndrome is an acute demyelinating
polyneuropathy characterized by an immunologic attack upon peripheral nerve myelin.
Clostridium perfringens type C (enteritis necroticans) a
Rare, in developed countries, where it has been seen primarily in diabetics. Sporadically in parts of Asia, Africa, and the South Pacific, where it primarily affects children with severe protein malnutrition.
Cooked poultry and cooked pork
High mortality in protein- deficient persons, associated with
malnutrition and a diet rich in trypsin inhibitors
Clostridium botulinum (types A and B) a
Rare; sporadic. Infant botulism results from the ingestion of the C.
botulinum spores, subsequent colonization of the small intestine with release of neurotoxins.
Honey (infants under
1 year of age) Infant botulism, if untreated, may progress to cause paralysis of the respiratory muscles, arms, legs, and trunk.
Cronobacter species (C.
sakazakii)
Low; while Cronobacter infection can rarely occur in adults and children, neonatal and infant infections have been associated particularly with C. sakazakii.
Powdered infant formula (temperature abuse of dehydrated infant formula)
Causes death in infants <6 months of age (up to 70% mortality rate among neonates).
E. coli (EPEC and ETEC) a
Low; comprise a small proportion of enterovirulent E. coli, the species have been associated with diarrheal illness of all age groups from diverse global locations.
Untreated water; food contaminated by non-potable water or infected food handler.
Symptoms are mild, but can be severe in infants; major cause of infant mortality in certain regions;
travelers’ diarrhea.
Listeria monocytogenes a
Low; sporadic; occasionally epidemic.
Foods where multiplication has occurred during storage (see list above).
High-risk groups include immunocompromised persons and pregnant women; high mortality (ca. 25%) in high risk
populations; infrequent illness in immunocompetent persons; low numbers of L. monocytogenes are frequently consumed in foods.
Salmonella spp.a Rare; incidence salmonellosis among infants, higher than other age groups, has been associated with powdered infant formula.
Powdered infant formula and foods for infants <1 year of age.
Infants <1 year of age at risk for septicemia.
(continued) Table 8.2 (continued)
Microorganism Frequency of involvement
in foodborne disease Examples of vehicles
associated with outbreaks Other factors contributing to significance
8 Selection of Cases and Attributes Plans
177
Vibrio vulnificusa Low, sporadic; present in marine environments such as estuaries, brackish ponds, or coastal areas.
Raw oysters High mortality (ca. 50%) among persons that have elevated levels of serum iron; and those with liver disorders associated with high alcohol consumption.
Parasites Cryptosporidium parvuma
Medium; sporadic;
endemic;
occasionally epidemic.
Untreated water;
unpasteurized apple juice, contaminated produce, and unpasteurized milk.
Severe prolonged diarrhea that is life-threatening in immunocompromised;
prognosis is poor for AIDS patients; usually short term diarrhea that resolves
spontaneously in immunocompetent persons.
Toxoplasmaa gondii
Medium; infection (close to 30% of the world population may be infected with Toxoplasma) but with sporadic illnesses.
Undercooked, contaminated meat (especially pork, lamb, and venison) with cysts, any food or water contaminated with oocycsts, or through contacts with cat feces that contain Toxoplasma.
Usually asymptomatic in healthy people, but infection in pregnant women can result in fetal death, central nervous system abnormalities or eye disease in children.
Severe toxoplasmosis could be developed in immunocompromised people.
Viruses Hepatitis A virusa
Medium; common in certain regions;
severe disease more common in developed world.
Raw or underprocessed bivalve mollusks, produce (e.g., green onions, semi-dried tomatoes, frozen berries), untreated water.
Very severe for patients with liver disease, convalescence prolonged. Illness in adults more severe than in children. Lifelong immunity and vaccine available.
Hepatitis E virusa Low; found worldwide, but with the highest prevalence in East and South Asia and Sub-Saharan Africa.
Common in developing countries.
Contaminated water.
Sporadic cases have been linked to raw or undercooked pig liver/
sausages.
Usually self-limiting, but may develop into acute liver failure. Pregnant women are at greater risk of obstetrical complications and mortality from hepatitis E, which can induce a mortality rate of 20% among pregnant women in their third trimester.
Cases of chronic hepatitis E infection have been reported in immunosuppressed people.
III.C. Serious to Severe hazard for mycotoxins, acute or chronic dependent on exposure.
Fungi IARC
Classificationb Examples of vehicles
associated with outbreaks Other factors contributing to significance
Aflatoxins, produced by Aspergillus flavus, A. nomius and A. parasiticus
(aflatoxicosis)
Group 1, carcinogenic to humans.
Nuts, tree nuts, oilseeds, especially peanuts and maize, and dried figs in warmer climates.
Most potent liver carcinogens known; acutely toxic in high doses; carcinogenic, teratogenic and probably
immunosuppressive at low levels.
Fumonisins, produced mostly by Fusarium verticillioides and F. proliferatum
Group 2B, possibly carcinogenic to humans.
Fungus endemic in maize, toxins present in staple diets in regions of high maize consumption.
Immunosuppressive, carcinogenic to rats and probably man, implicated in esophageal cancer.
(continued) Table 8.2 (continued)
Microorganism Frequency of involvement in foodborne disease
Examples of vehicles associated with
outbreaks Other factors contributing to significance
8.4 Categorizing Microbial Hazards According to Risk