Food Safety 325complex, giving increased opportunities for food
contamination. International trade in foods has
expanded dramatically, and today the Food and
Agriculture Organization of the United Nations
(FAO) estimates over 500 million tonnes of food,
valued around US$400–500 billion, move in interna-
tional trade annually. Globalization of the food trade
presents a major challenge to food safety control
authorities, in that food can become contaminated in
one country and cause outbreaks of food-borne
illness in another. It is not unusual for an average
meal to contain ingredients from many countries that
have been produced and processed under different
standards of food safety.
Chronic effects of food-borne illness
Food-borne diseases are classifi ed as either infections
or intoxications. Food-borne infections are caused
when viable microorganisms are ingested and
these can then multiply in the human body.
Intoxications are caused when microbial or naturally
occurring toxins are consumed in contaminated
foods. Illnesses that relate to the consumption of
foods that are contaminated with chemical toxins or
microorganisms are collectively referred to as food
poisoning.
The health consequences of food-borne illness are
varied and depend on such factors as the individual’s
susceptibility, the virulence of the pathogen, and the
type of disease. Symptoms are often mild and self-
limiting in healthy individuals and people recover
within a few days from acute health effects. Acute
symptoms include diarrhea, stomach pain and
cramps, vomiting, fever, and jaundice. However, in
some cases microorganisms or their products are
directly or indirectly associated with long-term
health effects such as reactive arthritis and rheuma-
toid syndromes, endocarditis, Reiter syndrome,
Guillain–Barré syndrome, renal disease, cardiac and
neurological disorders, and nutritional and other
malabsorptive disorders. It is generally accepted that
chronic, secondary after-effect illnesses may occur in
2–3% of cases of food-borne infections and that the
long-term consequences to human health may be
greater than the acute disease. In one salmonellosis
outbreak, associated with drinking contaminated
milk, about 2% of patients developed reactive arthri-
tis. It is estimated that up to 10% of patients with
hemorrhagic colitis develop hemolytic uremic syn-
drome (HUS), a life-threatening complication
of Escherichia coli O157:H7 infection characterized
by acute renal failure, hemolytic anemia, and
thrombocytopenia.Vulnerable groups
Vulnerable groups tend to be more susceptible to
food-borne infections and generally suffer more
severe illness because their immune systems are in
some way impaired. The immune system of infants
and young children is immature. In pregnant women,
increased levels of progesterone lead to the downreg-
ulation of cell-mediated immunity, increasing the
susceptibility of both mother and fetus to infection
by intracellular pathogens (Smith, 1999). In older
people, a general decline in the body’s immune
response occurs with age, as does a decrease in
stomach acid production. Immune responses in older
people are also adversely affected if that person is
malnourished through poor diet. Furthermore, age-
related loss of sensory abilities, such as sight and taste,
can lead to diffi culties in choosing and preparing
food. An aging population is one factor infl uencing
the increase in the prevalence of food-borne disease.
In 1999, 20% of Europe’s population was older than
60 years of age, but this is predicted to rise to 35% by
2050 (Kaferstein, 2003). Other groups in which the
immune system may be suppressed, making them
more susceptible to food-borne infection, include
cancer patients, transplant patients receiving immu-
nosuppressant drugs, and patients with acquired
immunodefi ciency syndrome (AIDS). In nonindus-
trialized countries, political unrest, war, and famine
lead to increased malnutrition and can expose poorer
populations to increased risk of food-borne disease.Improved surveillance
Improved surveillance systems lead to an increase in
the reported incidence of food-borne disease. Using
information technology, many countries have devel-
oped enhanced surveillance systems to gain a better
picture of the true incidence of food-borne disease.
International outbreaks are more readily detectable
with the use of electronic databases for sharing molec-
ular typing data (such as PulseNet in the USA and
EnterNet in Europe) and rapid alert systems, websites,
or list servers. However, even with this enhanced sur-
veillance, it is unlikely that statistics refl ect the true
incidence of food-borne disease worldwide.