BLBS102-c41 BLBS102-Simpson March 21, 2012 14:25 Trim: 276mm X 219mm Printer Name: Yet to Come
792 Part 8: Food Safety and Food AllergensTable 41.2.The Incidence of the Four Most Frequent Foodborne Disease-Causing
Pathogens in Canada and the United StatesEstimated Cases/Year (Based on Population Ratio)Bacteria Canada United StatesaCampylobacter 110,000–700,000 1,100,000–7,000,000
Listeria 93–177 928–1767
Salmonella 69,600–384,000 696,000–3,840,000
VerotoxigenicE. coli(Including
E. coliO157:H7)1600–3200 16,000–32,000Total 181,3000–1,087,400 1,812,900–10,873,800aAdapted from Buzby and Roberts 1997.number of reported cases ofSalmonella, Campylobacter, and
E. coliO157 increased from 2- to 40-fold between 1982 and 1994
(Sharp and Reilly 2000). The increase in the number of cases
was attributed to heightened awareness of foodborne related ill-
ness, improved diagnostic methods, and improved reporting and
surveillance procedures.Campylobacteris currently the leading
cause of foodborne disease in the United States and Canada,
followed bySalmonella-related infections. The numbers of es-
timated cases of foodborne illness per year in the United States
and Canada countries are listed in Table 41.2. Although the
number ofListeria monocytogenes–related infections is consid-
erably lower than those of other pathogens, foodborne infections
caused by this organism are characterized by a high case mor-
tality ratio, especially in certain high risk groups such as the
elderly, the young, immunocompromised individuals, and preg-
nant women. Infections caused byE. coliO157:H7 often result
in a high morbidity and mortality rate. For example, complica-
tions such as hemolytic uremic syndrome can result in kidney
failure and death (Riley et al. 1983, Karmali 1989). Sources of
bacterial infections are not limited to contaminated foods; con-
taminated water and person-to-person transmission have also
been implicated. For example, in a waterborne outbreak of
E. coli0157:H7 in Walkerton, Ontario, 1700 cases and seven
deaths were reported. This led to changes in the Ontario Drink-
ing Water Regulations to include strict water treatment proce-
dures and zero tolerance for the presence of coliforms andE.
coliin drinking water. Current food safety programs in the food
industry must now document the use of pathogen-free water in
food production and processing facilities.CAMPYLOBACTEREnteritisCampylobacter jejuniandC. coliare the species ofCampy-
lobacterimplicated in mostCampylobacterenteritis infections.
Other species ofCampylobactersuch asC. lariandC. up-
saleusismay also causeCampylobacterenteritis. Symptoms of
Campylobacterinfection in humans are watery and/or bloody di-
arrhea, abdominal pain, fever, and general malaise. The disease
is usually self-limiting, and antibiotics are required only when
complications occur. It is estimated thatCampylobacterenteri-tis accounts for 10% of cases of foodborne illness, and death
is rarely reported. Most cases of this disease are sporadic, and
foods of animal origin, particularly poultry, are largely responsi-
ble for most infections. Contaminated fruits and vegetables have
also been implicated inCampylobacterenteritis cases.SalmonellosisSalmonellosis infection ranks second in incidence toCampy-
lobacterenteritis. This organism is ubiquitous (present every-
where) in the environment, especially in the feces of most food-
producing animals; hence, a variety of foods are readily con-
taminated by this organism.Salmonellaare present in animals
without causing apparent illness. However, certain serotypes of
Salmonellasuch asS. enteritidiscan penetrate poultry repro-
ductive organs, resulting in contamination of egg content and
posing a health risk to consumers. Salmonellosis symptoms in-
clude watery diarrhea, abdominal pain, nausea, fever, headache,
and occasional constipation. Hospitalization may be required in
cases of severe infections. Foods that can become contaminated
withSalmonellainclude meat, raw milk, poultry, eggs, dairy
products, and other types of foods that can become contami-
nated with fecal material. An increase in the number of cases
of Salmonellosis linked to consumption of contaminated fruits
and vegetables such as bean sprouts, raw tomatoes, melons, and
cantaloupes has been reported. In addition to fecal contamina-
tion, cross-contamination of foods bySalmonelladuring food
preparation can be a source of foodborne illness.ListeriosisListeriosis is caused byListeria monocytogenes. The ubiquitous
nature of this organism contributes to the widespread incidence
of the organism in foods. It is psychrotrophic in nature and is
able to grow at refrigeration temperatures. Hence, this organism
is of concern in refrigerated foods with extended shelf life. Lis-
teriosis infections often result in septicemia and/or meningitis.
The case mortality ratio for Listeriosis infections is much higher
than those ofSalmonella,Campylobacter,andE. coli0157:H7
infections. An estimated 500 deaths associated with Listeriosis