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Foodborne Pathogenic Microorganisms
and Natural Toxins Handbook
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Infective Dose Information
Most chapters include a statement on infectious dose. These
numbers should be viewed with caution for any of the following
reasons:
- Often they were extrapolated from epidemiologic
investigations.
- They were obtained by human feeding studies on healthy, young
adult volunteers.
- They are best estimates based on a limited data base from
outbreaks.
- They are worst case estimates.
- Because of the following variables they cannot be directly used
to assess risk:
Variables of the Parasite or Microorganism
- Variability of gene expression of multiple pathogenic
mechanism(s)
- Potential for damage or stress of the microorganism.
- Interaction of organism with food menstruum and
environment
- pH susceptibility of organism
- Immunologic "uniqueness" of the organism
- Interactions with other organisms
Variables of the Host
- Age
- General health
- Pregnancy
- Medications--OTC or prescription
- Metabolic disorders
- Alcoholism, cirrhosis, hemochromatosis
- Malignancy
- Amount of food consumed
- Gastric acidity variation: antacids, natural variation,
achlorhydria
- Genetic disturbances
- Nutritional status
- Immune competence
- Surgical history
- Occupation
Because of the complexity of factors involved in making risk
decisions, the multidisciplinary Health Hazard Evaluation Board
judges each situation on all available facts.
December 1991
M. Walderhaug