can result from any one of several plausible
causes. Although the sanitarian is most
interested in those related to microbial ori-
gin, other causes are chemical contaminants,
toxic plants, animal parasites, allergies, and
overeating. Each of these conditions is rec-
ognized as a potential source of illness in
human. Subsequent discussions will be con-
fined to those illnesses caused by microor-
ganisms.
Foodborne Disease
A foodborne disease is considered to be
any illness associated with or in which the
causative agent is obtained by the ingestion
of food. A foodborne disease outbreakis
defined as “two or more persons experienc-
ing a similar illness, usually gastrointestinal,
after eating a common food, if analysis iden-
tifies the food as the source of illness.”
Approximately 66% of all foodborne illness
outbreaks are caused by bacterial pathogens.
Of the 200 foodborne outbreaks reported
each year, approximately 60% are of unde-
termined etiology. Unidentified causes may
be from the SalmonellaandCampylobacter
species,Staphylococcus aureus,Clostridium
perfringens,Clostridium botulinum, Listeria
monocytogenes, Escherichia coli O157,
Shigella,Vibrio, and Yersinia enterocolitica,
which are transmitted through foods. A wide
variety of home-cooked and commercially
prepared foods have been implicated in out-
breaks, but they are most frequently related
to foods of animal origin, such as poultry,
eggs, red meat, seafood, and dairy products.
Foodborne illnesses
Food poisoning is considered to be an ill-
ness caused by the consumption of food con-
taining microbial toxins or chemical poisons.
Food poisoning caused by bacterial toxins is
calledfood intoxication; whereas, that caused
by chemicals that have gotten into food is
referred to as chemical poisoning. Illnesses
caused by microorganisms exceed those of
chemical origin. Illnesses that are not caused
by bacterial by-products, such as toxins, but
through ingestion of infectious microorgan-
isms, such as bacteria, rickettsia, viruses, or
parasites, are referred to as food infections.
Foodborne illnesses caused from a combina-
tion of food intoxication and food infection
are called food toxicoinfections. In this food-
borne disease, pathogenic bacteria grow in
the food. Large numbers are then ingested
with the food by the host and, when in the
gut, pathogen proliferation continues, with
resultant toxin production, which causes ill-
ness symptoms. Illness caused by the mind,
due to one witnessing another human sick or
to the sight of a foreign object, such as an
insect or rodent, in a food product, is termed
psychosomatic food illness.
To provide protection against foodborne
illness, it is necessary to have up-to-date
knowledge of production, harvesting, and
storage techniques to accurately evaluate the
quality and safety of raw materials. Thor-
ough knowledge of design, construction,
and operation of food equipment is essen-
tial to exercise control over processing,
preservation, preparation, and packaging of
food products. An understanding of the vul-
nerability of food products to contamina-
tion will help establish safeguards against
food poisoning.Aeromonas hydrophilaFoodborne Illness
Evisceration and cold storage of chickens
at 3ºC may permit an increase in A. hydro-
phila. Chill waters and the evisceration pro-
cess itself appear to be probable sources of
contamination in the typical broiler process-
ing operation and may contribute to the high
efficiency of occurrence of this microorgan-
ism at the retail level. This microorganism
has been isolated from raw milk, cheese, ice