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834 Part 8: Food Safety and Food Allergensillness (Schraff 2010). The Centers for Disease Control (CDC)
annual food-borne disease report posted through the FoodNet
data site reports incidences of illness based on data from ten
sentinel sites across the United States. The data cover approx-
imately 46 million people representing approximately 15% of
the population. Current data suggest that the incidence of infec-
tions caused byCampylobacter,Salmonella,Listeria, and shiga
toxin-producingEscherichia coli(STEC),Yersinia,andShigella
(CDC 2010) is declining.
While focusing on food-borne pathogens in this review it
is important to define what this review means by an “emerg-
ing food-borne pathogen.” Mor-Mur and Yuste (2010) suggest
that there are pathogens not previously known (new pathogens),
others that have arisen as food-borne (emerging pathogens),
and others that have become more potent with other products
(evolving pathogens). Emerging pathogens are therefore present
strains that are adapting to stresses in new environments. Emerg-
ing pathogens that have newly arisen have been recognized as a
pathogen for many years and are now associated with food-borne
transmission (Meng and Doyle 1997, 1998, Sofos 2008). While
a considerable number of pathogens are present and capable of
causing disease in foods, there are over 200 recognized natural
chemical and physical agents (Acheson 1999). Perhaps the most
important and emergent areCampylobacter jejuni,Salmonella
typhimuriumDT104,E coliO157:H7, and other enterohem-
orrhagicE. coli(EHEC) and STEC,Listeria monocytogenes,
Arcobacter butzleri,Mycobacterium aviumsbspparatuberculo-
sis,Aeromonas hydrophila, andCronobacter sakazakii. Other
agents of emergence include prions, viruses, (noroviruses, hep-
atitis A, rotavirus), severe acute respiratory syndrome (SARS),
and parasites such asAscaris,Cryptosporidium,andTrichinella.
Also of concern is the emergence of antibiotic-resistant strains in
pathogens such asSalmonella,Campylobacter,Shigella,Vibrio,
Staphylococcus aureus,E. coli, andEnterococci.
There are a number of factors that contribute or have had an
influence on the changing trends in food-borne disease; Newell
et al. (2010) provides an excellent overview of changes that have
occurred and contribute to the changing trends in food-borne
disease. Some of the highlights include: a rapid increase in the
human population and a shift towards an aging population; an in-
creasing global market for foods, transportation, travel, changes
in eating habits, a greater population of immunocompromised,
and changes in farming practices and so on.
Ray (2004a) cites other factors including some which overlap
with Newell et al. (2010) that can be attributed to our recogni-
tion of how we can define an emerging food-borne pathogen.
There is an overall better knowledge of food-borne pathogens:
previously, outbreaks linked to foods were screened for a range
of standard pathogens but over the years we have expanded the
repertoire to include new pathogens. Perhaps our abilities to
test for new pathogens are based on our understanding of them.
Technologies incorporating molecular analysis and the use of
genomics have expanded our capabilities of what to search for.
So too does the technology available to rapidly screen and iden-
tify greatly expand our knowledge.
Improvements in regulations and the actions of regulatory au-
thoritieshave enhanced our capabilities to rapidly identify andmonitor for emerging threats. Regulatory authorities at the state
and national levels are able to collate data regarding specific
outbreaks and the modes of transmission or vehicles implicated
in food-borne outbreaks. On the basis of this type of criteria
it is possible to make recommendations regarding criteria for
what is acceptable and what is not, as well as methods to detect
pathogens of concern. These agencies have also developed or
guide the development of appropriate sanitation procedures to
reduce the risk of human disease or educate consumers in safe
handling practices. In the United States, agencies such as United
States Department of Agriculture Food Safety and Inspection
service (USDA FSIS), and the Food and Drugs Administration
(FDA) direct some of these activities, while in Europe, the Eu-
ropean Food Safety Authority (EFSA) has a similar role.
Changes in the lifestyle habits of consumershave changed
significantly in the last 50 years. These have included traveling,
(domestic and international), changes in consumer eating habits,
(close to half of every dollar earned is spent eating out), the
types of food consumed has changed, and there are increases
in seafood consumption, exotic foods, cheeses, and minimally
processed or more fresh or natural foods as well as greater access
to a larger variety of fresh and raw foods that are imported.
New processing technologieshave led to faster and more ef-
ficient ways to produce foodstuffs for larger retail markets and
consequently there is considerably more product distributed over
a wide area—examples of the effects of this have been seen in the
outbreak of listeriosis associated with the consumption of con-
taminated hotdogs distributed nationally (CDC 1998, Donnelly
2001).
Some additional factors that may contribute to the emergence
of food-borne pathogensinclude the recognition of illness as-
sociated with multiple strains ofE. colitermed STEC (Eblen
2007), or strains that appear to be emergent as a result of trans-
fer of resistance and other genetic virulence properties (Fricke
et al. 2009), additional factors that warrant inclusion here are
also related to the transfer of antimicrobial resistance and the se-
lection of drug-resistant strains, which can become dominant in
a food system (Endtz et al. 1991, Aarestrup and Engberg 2001,
Engberg et al. 2001, Nielsen et al. 2006, Logue et al. 2010)
and have potential links to disease that is difficult to treat. Also
of interest are the capabilities of certain pathogens to grow at
refrigeration temperatures (Listeria,Yersinia,Aeromonas) and
the ability to survive in low-pH (acid) foods (E. coliO157:H7,
Salmonella,Listeria).
In this chapter, we address emerging food-borne pathogens
of human disease and their potential impacts on human health
and methods for their detection. In general, trends in addressing
disease have shown a reduction (downward trends). The latest
data from the CDC shows prevalence in sentinel states has been
decreasing (CDC 2010).Emerging Food-Borne PathogensSalmonellaNontyphoidalSalmonellais a major cause of food-borne dis-
ease in industrialized countries. In the United States alone, it