Chapter 22
Introduction to Foodborne
Pathogens
INTRODUCTION
Although a number of different infectious diseases may be contracted from foods under certain
circumstances, there are those that are contracted exclusively or predominantly from the consumption
of food products. Two examples of the former are hemorrhagic colitis and listeriosis and of the latter
are botulism and staphylococcal food poisoning. Anthrax and brucellosis are two diseases that have in
decades past been contracted from eating diseased animals, but, with the prevalence of these diseases
being so low, they are rarely if ever contracted via the foodborne route. The recognized foodborne
pathogens include multicellular animal parasites, protozoa, fungi, bacteria, viruses, and prions (Exhibit
22–1). An overview of these organisms is presented in this chapter relative to their general habitats,
their entry into foods, and general mechanisms of pathogenesis, and how they differ from closely
related nonpathogenic species/strains. More details on each can be found in the respective chapters
that follow.
Foodborne Illness Cases in the United States
The Centers for Disease Control and Prevention (CDCP) is the federal agency that gathers, analyzes,
maintains, and reports statistics on all human diseases in addition to its other vast activities related
to human health. In spite of the research and surveillance activities of this agency, there is no exact
count of the number of foodborne illnesses for any year, and there are many reasons for this. First
and foremost is the fact that not all foodborne illnesses are reported to health authorities at any level.
Another important factor is the lack of a reporting requirement for foodborne illnesses caused by B.
cereus, C. perfringens, S. aureus, and some other agents; and this leads to an undercount of these
syndromes in any given year. For example, for B. cereus cases, the CDCP estimates the number of
cases to be 38 times the number of reported cases (see reference 72). Although botulism cases are
reported, the CDCP assumes that the actual number for a given year is two times the reported number,
and that 100% of reported cases are foodborne. On the other hand, L. monocytogenes is reported and
is covered by sentinel site surveillance (see below) but the total cases are estimated to be two times
the reported cases. Foodborne shigellosis is estimated to be 20 times the reported cases but only 20%
of this number is estimated to be foodborne (see reference 72).
519
Introduction to Foodborne
Pathogens
INTRODUCTION
Although a number of different infectious diseases may be contracted from foods under certain
circumstances, there are those that are contracted exclusively or predominantly from the consumption
of food products. Two examples of the former are hemorrhagic colitis and listeriosis and of the latter
are botulism and staphylococcal food poisoning. Anthrax and brucellosis are two diseases that have in
decades past been contracted from eating diseased animals, but, with the prevalence of these diseases
being so low, they are rarely if ever contracted via the foodborne route. The recognized foodborne
pathogens include multicellular animal parasites, protozoa, fungi, bacteria, viruses, and prions (Exhibit
22–1). An overview of these organisms is presented in this chapter relative to their general habitats,
their entry into foods, and general mechanisms of pathogenesis, and how they differ from closely
related nonpathogenic species/strains. More details on each can be found in the respective chapters
that follow.
Foodborne Illness Cases in the United States
The Centers for Disease Control and Prevention (CDCP) is the federal agency that gathers, analyzes,
maintains, and reports statistics on all human diseases in addition to its other vast activities related
to human health. In spite of the research and surveillance activities of this agency, there is no exact
count of the number of foodborne illnesses for any year, and there are many reasons for this. First
and foremost is the fact that not all foodborne illnesses are reported to health authorities at any level.
Another important factor is the lack of a reporting requirement for foodborne illnesses caused by B.
cereus, C. perfringens, S. aureus, and some other agents; and this leads to an undercount of these
syndromes in any given year. For example, for B. cereus cases, the CDCP estimates the number of
cases to be 38 times the number of reported cases (see reference 72). Although botulism cases are
reported, the CDCP assumes that the actual number for a given year is two times the reported number,
and that 100% of reported cases are foodborne. On the other hand, L. monocytogenes is reported and
is covered by sentinel site surveillance (see below) but the total cases are estimated to be two times
the reported cases. Foodborne shigellosis is estimated to be 20 times the reported cases but only 20%
of this number is estimated to be foodborne (see reference 72).
519