Preharvest Food Safety

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Preharvest Food Safety
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Why pre-harvest food safety ought to be
considered.....

• The evidence that farms serve as reservoirs for
  certain foodborne agents is overwhelming.
• The disease/pathology based inspection system has
  little impact on preventing farm-origin pathogens
  from entering the food supply.
• Pre-harvest control has worked for some foodborne
  agents
• Complete control at processing and consumer
  stages is not possible
• Interventions at all levels of the food chain
  will result in the safest food (multiple
  hurdles approach).

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Evidence that domestic animals are reservoirs for
certain enteric disease agents

• Outbreak investigations
• Casecontrol of sporadic cases
• Microbiological data from farm to table
• Molecular epidemiology
• Contrast typhoidal and non-typhoidal
  Salmonellosis

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Risk factors for Sporadic E. coli O157H7 cases
From CDC Foodnet CID 20438-S271, 2004
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Risk factors for Sporadic campylobacteriosis cases
From CDC Foodnet CID 20438-S285, 2004
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Case control studies examining risk factors for
Toxoplasma gondii infection during pregnancy.
Odds ratios for selected exposures.
NS not significantly different from 1 NE not
examined
Kapperud, Am J Epi 144405, 1996 Baril, Scan J
Inf Dis 31305, 1999 Cook, BMJ 321142, 2000
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From Elder RO, et al, PNAS, 972999, March 28
,2000
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Jack in the Box outbreak,
WA ID NV CA
contaminated lot of ground beef patties served in
all 4 states
Human cases
Barrett, J Clin Microbiol. 1994 December 32(12)
30133017.
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(No Transcript)
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Multiple hurdles for control of disease
associated with shigatoxin-producing E. coli O157
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Possible means of pre-harvest control

• Eradication/Biosecurity
• Universal testing
• Competitive exclusion
• Vaccination
• Immediate pre-slaughter measures
• Niche engineering

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