326 Introduction to Human Nutrition
Economic consequences of
food-borne illness
As well as morbidity and mortality associated with
food-borne diseases, there are direct economic costs
incurred, including the cost of medical treatment
and industry losses. WHO estimates that in the USA
diseases caused by the major food-borne pathogens
have an annual cost of up to US$35 billion. The
annual cost for illness due to E. coli O157 infections
in the USA has been estimated at US$405 million,
which includes costs for medical care (US$30 million),
lost productivity (US$5 million) and premature
deaths (US$370 million); however, this estimate does
not include costs due to pain and suffering, and
expenditure on outbreak investigations (Frenzen et
al., 2005). The cost of salmonellosis in England and
Wales in 1992 was estimated at between US$560
million and US$800 million. Over 70% of costs were
directly associated with treatment and investigation
of cases, and costs to the economy of sickness related
to absence from work. In 2006, Cadbury Schweppes,
the world’s largest confectionary company, were
forced to recall seven Cadbury-branded products in
the UK and two in Ireland due to Salmonella con-
tamination. The estimated cost of the product recall
was £30 million, including a £5 million marketing
campaign to rebuild consumer confi dence. In addi-
tion, Cadbury Ltd in the UK was fi ned £1 million
and ordered to pay costs totaling £152 000 for
distributing the contaminated chocolate products
which led to illness in 42 people being reported, three
of whom were hospitalized (Cadbury press release,
2007).
Bearing these fi gures in mind, the true estimates of
food-borne disease and the likely economic costs are
unknown. In industrialized countries only a small
proportion of cases of food-borne diseases is reported,
and even fewer are investigated. Very few non-
industrialized countries have established food-borne
disease reporting systems, and in those that have, only
a small fraction of cases is reported.
Emerging food safety issues
The emergence of new food-borne pathogens is one
factor leading to increased concern about food safety.
During the twentieth century improvements in sewage
treatment, milk pasteurization, and water treatments,
and better controls on animal disease have led to the
control of food-borne and water-borne diseases such
as typhoid, tuberculosis, and brucellosis. However,
new food-borne pathogens have emerged. Food-
borne organisms such as E. coli O157, Campylobacter
jejuni, and Salmonella Enteritidis phage type 4 were
virtually unknown in the 1970s, but have come to
prominence as virulent pathogens associated with
foods of animal origin. Cyclospora cayetanensis
emerged as a food-borne pathogen in 1995, when it
was associated with outbreaks of illness traced to
raspberries imported into the USA from Guatemala.
Cryptosporidium parvum emerged as a pathogen of
worldwide signifi cance during the 1990s and has been
linked to contaminated drinking water and to a range
of foods including salads, unpasteurized milk, and
apple juice. Some known pathogens such as Listeria.
monocytogenes have only recently been shown to be
predominantly food-borne and, since they can grow
at refrigeration temperatures, have increased in
importance with the expansion of the cold chain for
food distribution. Enterobacter sakazakii has recently
been implicated in outbreaks of infection associated
with powdered infant formula. Many of these emerg-
ing pathogens are of animal origin and do not usually
cause serious illness in the animal host.
Another concern is that a proportion of food-
borne illness is caused by pathogens that have not yet
been identifi ed, and therefore cannot be diagnosed.
In the USA, it is estimated that unknown food-borne
agents caused 65% of the estimated 5200 annual
deaths from food-borne disease (Mead, 1999; Frenzen,
2004). This is of concern since many of today’s
commonly recognized food-borne pathogens were
not recognized as causes of food-borne illness 30
years ago. In this regard, Mycobacterium avium sub-
species paratuberculosis (Map) is an organism of
potential concern. Map is the causative agent of
Johne’s disease in cattle, but it has been proposed that
Map is also the causative agent of Crohn’s disease in
humans, and that it may be transmitted via milk
(including pasteurized milk) and possibly other
foods.
During the 1980s and 1990s, antibiotic-resistant
food-borne pathogens emerged that are associated
with the inappropriate use of antibiotics in animal
husbandry. For example, Salmonella typhimurium
DT 104 routinely shows resistance to fi ve different
antibiotics. Strains of Salmonella and Campylobacter
are showing resistance to fl uoroquinolones since