Yersinia enterocolitica. Often found in raw milk,
chocolate milk, water, pork, other raw meats.
Spoiled milk is also mostly caused by bacteria
such asLactococcus cremorisorEnterobacter aero-
genes, that cause the milk to form long white strands.
Water contamination is usually due to the pres-
ence of three bacteria,E. coli,Clostridium perfringens,
and enterococci, the bacteria normally found in the
feces of people and many animals.
Parasitic food contamination
Parasites are organisms that lives in or on a host, and
obtain nourishment without benefiting or killing the
host. They enter the body through the mouth when con-
taminated food or drink is swallowed. There are many
different types and range in size from single-celled, micro-
scopic organisms (protozoa) to larger, multi-cellular
worms (helminths) that can be seen without a micro-
scope. Parasites that contaminate food include:
Entamoeba histolytica. Parasite that causes amoebic
dysentery, characterized by severe diarrhea. It is
transmitted by contaminated water, and is often
called ‘‘traveler’s dysentery’’ because of its preva-
lence in developing nations.
Giardia duodenalis. Microscopic parasite that can live
in the intestines of animals and people. It is found in
every region of the world and is one of the most
common causes of waterborne and foodborne) illness.
Cryptosporidium parvum. Microscopic parasite, a
significant cause of water contamination worldwide.
It is found in the intestines of many herd animals
including cows, sheep, goats, deer, and elk.
Cyclospora cayetanensis. Single-celled, microscopic
parasite. Little is known about this organism,
although cases of infection are being reported from
various countries with increasing frequency.
Toxoplasma gondii. Single-celled, microscopic para-
site found throughout the world. Found in foods
such as raw or undercooked meats, especially pork,
lamb, or wild game, and in drinking untreated water.
Trichinella spiralis. Intestinal roundworm whose lar-
vae may migrate from the digestive tract and form
cysts in various muscles of the body. In the United
States, infections are most prevalent where pork or
wild game is consumed raw or undercooked.
Taenia saginata/solium.Taenia saginata(beef tape-
worm) andTaenia solium(pork tapeworm) are para-
sitic worms (helminths). They are now uncommon in
the United States, although travelers and immigrants
are occasionally infected.
Precautions
Simple precautions can reduce the risk of contam-
ination. For instance, meat left at room temperature
promotes bacterial growth and refrigeration helps to
suppress it. One can also be careful about eating cer-
tain foods. Eating raw meats and fish should be
avoided as well as salads prepared in restaurants
where meats and vegetables share a common surface
during preparation.
Most food-related illnesses can be avoided by wash-
ing fresh fruits and vegetables, cooking meat thoroughly,
drinking only pasteurized milk, and common-sense
hygiene. Heating food to an internal temperature
above 160F, or 78C, is usually sufficient to killKEY TERMS
Amoeba—A single-celled organism, many species
of which live in free in water.
Amoebic dysentery—Disease characterized by
severe diarrhea, caused by infection of the gut by
Entamoeba histolytica.
Bacteria—Microorganisms found in the environ-
ment. Bacteria can multiply quickly in food, and
can cause foodborne illnesses. Not all bacteria are
harmful: some are used to make yogurt and cheese.
Contamination—The undesired occurrence of
harmful microorganisms or substances in food.
Cross-contamination—The transfer of harmful
bacteria from one food to another, or also from
hands to food.
Feces—Waste product of digestion formed in the
large intestine. About 75% of its mass is water, the
remainder is protein, fat, undigested roughage,
dried digestive juices, dead cells, and bacteria.
Foodborne illness—Illness caused by pathogenic
bacteria transmitted to humans by food.
Microorganism—A general term for bacteria,
molds, fungus, or viruses, that can be seen only
with a microscope.
Parasite—An organism that lives in or on a host; it
obtains nourishment from the host without benefit-
ing or killing the host. The parasites responsible for
foodborne illnesses are mostly single-cell organ-
isms such as amoeba, giardia, and trichomonas,
while others have a worm-like appearance.
Pathogen—A disease-causing microorganism.Food contamination