Fundamental Food Microbiology, Third Edition - Fuad Fathir

IMPORTANT FACTS IN FOODBORNE DISEASES 327
E. Predominant Etiological Agents
As indicated before, gastrointestinal disorders can be caused by the consumption
of food and water containing pathogenic microorganisms and their toxins; pathogenic
algae and parasites and their toxins; toxic chemicals, either natural or as a
contaminant; and by other factors. Among these, the largest number of outbreaks,
the total number of cases, and the number of deaths are caused by pathogenic
bacteria and their toxins. Data presented in Table 23.2 show that in the U.S., from
1983 to 1987, bacteria caused ca. 66% of the outbreaks affecting 92.2% of the
cases and 96.4% of the fatalities. 1–3 Outbreaks caused by viruses, parasites, and
chemicals were 4.5, 4.0, and 25.5%, respectively. The number of cases and deaths
from these agents were also low. No outbreak from molds was reported during
this period. Results of a similar U.S. study between 1972 and 1978 showed that
percentages of foodborne disease outbreaks and cases, respectively, were as follows:
bacterial, 66.3% and 90.9%; viral, 2.7% and 3.5%; parasitic, 7.8% and 1.1%,
and chemical 23.5% and 4.3%. This report did not include the number of fatalities.
Both reports indicated that pathogenic bacteria are the major cause of foodborne
diseases in the U.S. This is probably also true for other countries. Current information
for recent years, presented later, also shows the same trend (see Table
23.10). Several factors might be responsible for the high incidence caused by
pathogenic bacteria: many pathogenic bacteria are found in the raw food materials
of animal and plant origin, many are present in the food environments, many grow
very effectively in different foods, and many are not killed by the conditions used
for processing of different foods.
F. Types of Microbial Foodborne Diseases
Foodborne diseases in humans result from the consumption of either food and water
contaminated with viable pathogenic bacterial cells (or spores in the case of infant
botulism) or food containing toxins produced by toxigenic bacteria and molds. On
the basis of mode of illnesses, these can be arbitrarily divided into three groups:
intoxication or poisoning, infection, and toxicoinfection (Table 23.3).
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Table 23.2 Confirmed Foodborne Disease Outbreaks, Cases, and Deaths by Etiological
Agents from 1983 to 1987 in the U.S.
Etiological
Agentsa Outbreaks Cases Deaths
No. % No. % No. %
Bacterial 600 66.0 50,304 92.2 132 96.4
Viral 41 4.5 2,789 5.1 1 0.7
Parasiticb 36 4.0 203 0.4 1 0.7
Chemicalsc 232 25.5 1,244 2.3 3 2.2
Total 909 100 54,540 100 137 100
a No incidence from mycotoxins was reported.
b Includes Trichinella spiralis and Giardia.
c Includes Ciguatoxin, scombrotoxin, mushrooms, heavy metals, and other chemicals.