Poultry Inspection The Basis for a Risk-Assessment Approach (1987) / Chapter Skim
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4. Application of the Model to Microbiological Hazards
4. Application of the Model to Microbiological Hazards
Pages 56-99
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From page 56... ...
_ , Inspection methods in effect at that time were _ Specific recommendations to achieve this goal included education of producers, processors, food handlers, and consumers; determination of etiologic agents responsible for gross lesions resulting in condemnation; development of a trace-back capability to determine where pathogenic microorganisms contaminate the poultry between farm and table; and emphasis on the Hazard Analysis Critical Control Point (HACCP) concept in the inspection process (NRC, 1985b)
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From page 57... ...
For example, Escherichia cold is the dominant aerobic bacterium in all normal human stool samples, and most strains of E cold are harmless to a healthy adult; however, some carry specific virulence plasmids that have been associated with at least four distinct disease syndromes, including toxin-mediated secretory diarrhea and an invasive dysentery syndrome (Levine, 1985~.
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From page 58... ...
For ethical reasons, studies in volunteers are generally limited to healthy adults and to agents that cause only mild disease or for which there is good, effective therapy, but they can provide the best data on pathogenicity, permitting direct testing of Koch's postulates. These studies may also be useful in determining the relationship between dose and infection rates, in characterizing the disease syndrome, and, with an appropriate experimental design, in identifying specific virulence factors.
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From page 59... ...
Similarly, a study of disease outbreaks may demonstrate that one microorganism is significantly associated with illness among patients and is present in the food or other product incriminated as the cause of the outbreak. Epidemiological studies also permit characterization of microbial disease syndromes and can provide information on susceptibility and disease manifestations in persons other than normal healthy adults.
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From page 60... ...
Some infectious agents cause disease by producing toxins that may cause an incremental increase in the severity of illness with increasing toxin levels, rather than a threshold response. The botulinal toxin is one example: food-borne botulism is caused by a preformed neurotoxin present in contaminated food, and disease manifestations and severity correlate directly with the amount of toxin consumed.
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From page 61... ...
To completely characterize the risk associated with microbial contamination of chicken, there must be sufficient data from which to predict changes in disease occurrence that would result from changes in levels of product contamination at each of several steps from production to the consumer's table. Such data are likely to show an
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From page 62... ...
Yersinia enterocolitica 2. Bacteria known to be pathogenic in humans that have been associated with eating chicken: Bacillus cereus Clostridium botulinum Clostridium perfringens Shigella sppe Staphylococcus aureus
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From page 63... ...
Known Human Pathogens Carried on or Transmitted by Broiler Chickens at Retail CampYlobacter jejuni Hazard Identification and Evaluation. The gram-negative bacterium CampYlobacter ieiuni has recently been implicated as one of the most common bacterial causes of- gastroenter~t~s among both children and adults (Pai et al., 1979; Skirrow, 1977)
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From page 64... ...
Virulence factors and pathogenic properties of C jeJuni include invasiveness, enterotoxin production, and cytotoxin production (Kl~pstein et al., 1985~.
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From page 65... ...
Until national surveillance data are more complete, the best estimates of CampYlobacter incidence in the United States will continue to come from laboratories serving defined population groups. In the metropolitan area of Denver, Colorado, investigators found that the annual incidence of reported Campylobacter infections was 17.2 per 100,000 people (Blaser et al.
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From page 66... ...
(Grant et al., 1980; Smitherman et al., 1984) e Ce iejuni has been found at many points during slaughter and processing, and a significant proportion of the broiler chicken carcasses available for retail sale carry the microorganism (Table 4-1~.
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From page 67... ...
Sampled Percent Reference 40 30 Stern et al., 40 12.5 1984 36 69.4 Wempe et al ., 1983 36 66.7 94 82.9 Kinde et al., 1983 862 Chicken; supermarket shelf Whole, eviscerated chickens; chill tank exit in 1967 in 1979 Whole, eviscerated chickens; chill tank exit 862 597 28.6 601 36.9 Whole, eviscerated chickens; 171 20.5 chill tank exit Chicken; supermarket shelf 862 1.3 23.1 Harris et al., 1986b 4.3 Harris et al., 1986b Green et al., 1982 11.6 Campbell et al., 1983 Surkiewicz et al., 1969 Harris et al., 1986b Species of Campylobacter are present on a high percentage of chickens at the time of retail sale. Any reduction in the frequency or intensity of contamination may result in a corresponding reduction in the frequency of illness, but the commmittee found no studies that clearly support or refute this hypothesis.
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From page 68... ...
Nontyphoidal Salmonella Species Hazard Identification and Evaluation. Salmonella species are among the most common bacterial causes of gastroenteritis in humans.
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From page 69... ...
. Potential for Human Exposure.
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Yersinia enterocolitica is . recognized as a significant cause of acute enteritis and enterocolitis (Bottone, 1977~.
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From page 71... ...
In the United States serogroup 0:8 is the most common serogroup isolated, but this pattern may be changing (Bottone, 1983~. The invasive strains of plasmids encode, among other properties, the production of specific outer membrane proteins, calcium dependence, and adherence to HEp-2 tissue culture cells (Heesemann et al., 1984~; other proposed virulence factors, including invasion of HeLa cells and enterotoxin production, appear to be chromosomally mediated (Kay et al., 1983; Schiemann and Devenish, 1982~.
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From page 72... ...
Generally, however, raw chicken does not appear to be a major channel through which other pathogenic microorganisms enter the kitchen. Spore-forming microorganisms such as Bacillus cereus, Clostridium botulinum, and C
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From page 73... ...
inoculated vanilla sauce with a strain of B cereus isolated from an outbreak of food poisoning in Norway, and ingested about 200 ml of the sauce containing approximately 101° microorganisms; 13 hours later he experienced severe abdominal pain, diarrhea, and rectal tenesmus, which persisted for 8 hours.
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From page 74... ...
disease in the United States (Midura et al., 1970) and in several other outbreaks reported in the literature, but there are no good data on rates of isolation from raw chicken (Gilbert, 1979~.
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From page 75... ...
Consequently, disease severity is directly related to the amount of toxin present in the food. A dose of 10 g of purified botulinal toxin is probably sufficient to cause disease in a human; doses between 10-6 and 10g can be a lethal (Morris and Hatheway, 1983)
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From page 76... ...
Botulinal spores may be carried on raw chicken, but given the wide distribution of spores in the environment, there is no evidence that This is associated with an increased risk of illness. Microorganisms; Known to he Pathogen; c in (10 skins: That Are of Questionable Significance as Food-Borne Pathogens Transmitted by, Broiler Chickens Many other microorganisms, including bacteria, viruses, and parasites, are common causes of disease in poultry but play an uncertain role in human disease.
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From page 77... ...
sYnoviae causes both respiratory disease and infectious synovitis in poultry, current knowledge does not suggest that they pose a health hazard to consumers of broiler chickens. Nontuberculous mycobacteria, including those in the MYcobacterium avium complex, cause chronic pulmonary disease, lymphadenitis, other soft tissue infections, and bone and joint disease in humans (Wolinsky, 1979~.
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From page 78... ...
One hundred cases of Newcastle disease virus (NDV) infections in humans were reported frown 1943 to 1958 (Chang, 1981)
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From page 79... ...
The frequency with which these cases are due to person-to-person, water-borne, or food-borne transmission is unknown. USING THE RISK MODEL TO DEVELOP PROGRAMS AND STRATEGIES The need to reduce the public health risk associated with microbial contamination of foods, including poultry products, has been clearly established.
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From page 80... ...
. These comparative data on microbial contamination of passed and condemned carcasses are needed for evaluation of inspection procedures.
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From page 81... ...
For microorganisms that are known human pathogens, such as Yers~nia spp., more careful assessment of the potential for human exposure is needed; for example, evaluation of data on product contamination levels and acquisition of data on attributable risk (i.e., what percentage of cases can be attributed to chickens) similar to the study of Campylobacter conducted by the Seattle-King County Department of Public Health for FDA (SKCDPH, 1984)
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From page 82... ...
The HACCP systems would undoubtedly have some effect on disease incidence, but the limited studies reviewed in this chapter do not show a clear relationship between reduced contamination levels and the occurrence of illness. Numerous studies have documented both the expense and the frustration of trying to control microbial contamination of poultry and suggest that very strict guidelines for limiting microbial contamination during processing may not provide commensurate health benefits.
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From page 83... ...
The county would require a public health infrastructure that includes centralized laboratory facilities and prompt reporting to the epidemiologist in charge; microbiological competence for isolating and identifying specified pathogens; and the ability to perform epidemiological studies adequately so that risk factors can be identified for each infection found. Data on disease incidence in these counties could then be correlated with FSIS microbiological survey data, thereby permitting direct correlation of illness rates and microbial contamination levels.
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From page 84... ...
This might include increased emphasis on school education programs, development of adult consumer education materials, dissemination of information on public or commercial television or radio, or the development of product inserts describing proper handling techniques for poultry. Given the frequency of food-borne disease outbreaks associated with restaurants and institutions, efforts should also be directed toward reenforcing the importance of correct food-handling practices in those establishments.
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From page 85... ...
Compliance could be determined by physical measurement of contamination at critical control points and by analysis of microbial contamination, if any microbiological standards or guidelines were established. Surveillance to determine microbial contamination of the end products would provide a measure of the overall program's success in reducing the prevalence of human pathogens on market-ready poultry and would permit the tracking of trends in product contamination.
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From page 86... ...
1978. Epidemic Yersinia enterocolitica infection due to contaminated chocolate milk.
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From page 87... ...
1977. Yersinia enterocolitica: A panoramic view of a charismatic microorganism.
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From page 88... ...
1983b. Foodborne Disease Surveillance, Annual Summary 1981.
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From page 89... ...
1962 . The reaction to infection with the B1 strain of Newcastle disease virus in man.
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1974. The survival and growth of Bacillus cereus in boiled and fried rice in relation to outbreaks of food poisoning.
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1984. Genetically manipulated virulence of Yersinia enterocolitica.
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From page 92... ...
C~mpylobacter II: Proceedings of the Second International Workshop on Campylobacter Infections held in Brussels, September 6-9, 1983. Public Health Laboratory Service, London.
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From page 93... ...
1980. Yersinia enterocolitica infections and rheumatic diseases.
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From page 94... ...
1981. Bacillus cereus food poisoning.
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N . - associated virus closely related to avian infectious laryngotracheitis virus.
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Falkow. 1981 e Characterization of plasmids and plasmid-associated determinants of Yersinia enterocolitica pathogenesis.
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From page 97... ...
1978. Isolation of Yersinia enterocolitica from raw milk.
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From page 98... ...
1982. Human Yersinia enterocolitica infections in Wisconsin: Clinical, laboratory and epidemiologic features.
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From page 99... ...
19770 Severe systemic and pyogenic infections with Bacillus cereus.
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