Marguerite A Neill

Implied in the concept of food "safety" is that there is a risk of illness associated with its ingestion. Transmission of disease by food has been recognized since Biblical times, and the then current concept of food safety was straightforward and simple - namely, exposure avoidance. It has been a relatively modern construct that food could be made safer and healthier - safer from specific risks to thus prevent transmission of infection, but also healthier to prevent disease and promote health. Improved nutritional content through food fortification has eliminated the major nutritional deficiencies of goiter (iodine), rickets (vitamin D), and pellagra (niacin) in the developed world, and decreases in microbial contamination have decreased specific infectious food-borne diseases as well. The availability of safer and healthier foods is considered one of the ten great public health achievements of the twentieth century in the United States (CDC, 1999a, 1999b).

Both acute and chronic illness may occur following consumption of tainted food (Tauxe and Neill, 2006). While diarrheal illness has traditionally been considered the main manifestation of food-borne disease, several other clinical manifestations are now recognized, ranging from hepatitis, sepsis, meningitis, and paralysis to chronic neurologic disease (see Table 8.1). The microbial agents that cause these illnesses are diverse, and include bacteria, mycobacteria, viruses, parasites, and probably prions. Since 1990, eleven emerging pathogens to humans have been recognized (Nipah, Hendra, Hanta, West Nile, avian influenza and SARS viruses, Escherichia coli O157:H7, Vibrio choierae O139, Cyclospora, cryptosporidium, and variant Creutzfeld-Jacob disease, or vCJD). All but two (V choierae O139, Cyclospora) came from zoonotic sources, and of the nine with zoonotic origin three have been food-borne (E. coii O157:H7, Cyclospora and, probably, vCJD). While many factors converge to facilitate the emergence of a pathogen (IOM, 2003), of note are those most relevant to new food-borne pathogens (see Table 8.2). Since these factors are neither static nor self-limited, it should be anticipated that additional food-borne pathogens will emerge even

Table 8.1 Clinical spectrum of food-borne illness and examples of common

causative agents

Type of illness

Examples of causative agents

Acute enteric illness

• Nausea and vomiting within 6 hours

Staphylococcus aureus, Bacillus cereus

• Vomiting and diarrhea

Norovirus, rotavirus

• Diarrhea and abdominal cramping

ETEC, EPEC, Clostridium perfringens

• Diarrhea and fever

Non-typhoidal Salmonellae

Vibrio

• Bloody diarrhea

E. coli O157:H7

Campylobacter jejuni

Shigellae

Vibrio parahemolyticus

Enteric fever

Salmonella typhi

Brucella

Acute sepsis

V. vulnißcus

Acute hepatitis

Hepatitis A virus

Acute pseudoappendicitis

Yersinia enterocolitica,

Y. pseudotuberculosis

Acute neurological illness

• Paralysis

Botulism

Paralytic shellfish poisoning

Guillain-Barre syndrome

• Paresthesias

Scombroid, ciguatera

• Meningitis

Listeria monocytogenes

Chronic enteric illness

• Diarrhea >3 weeks

Giardia

Cryptosporidium parvum

Cyclospora cayetensis

Brainerd diarrheal syndrome

Chronic neurologic illness

• Seizures (neurocysticercosis)

Taenia solium

• Congenital abnormalities

Toxoplasma gondii

• Encephalitis (AIDS patients)

Toxoplasma gondii

Chronic anemia

Hookworm

Vitamin B-12 deficiency

Diphyllobothrium latum

if more traditional ones (e.g. Salmonella typhi, Mycobacterium tuberculosis) are controlled or eliminated. The question is not "if" new pathogens will be recognized, but when, to which microbial sector will they belong, who will be most affected, and what will be the burden of disease?

Table 8.2 Factors in the emergence of food-borne pathogens

• Microbial adaptation

• Human susceptibility to infection

• Human demographics and behavior

• Economic development and land use

• International travel and commerce

• Technology and industry

Reprinted with permission: Institute of Medicine (2003a).

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