Fundamental Food Microbiology, Third Edition - Fuad Fathir

NEW AND EMERGING FOODBORNE PATHOGENS 419
reasons for these changes can be attributed to many factors, some of which include
changes in our food consumption pattern, modern innovation in food processing
and retailing technologies, changes in agriculture and animal husbandry practices,
increase in food imports from many countries due to changes in the trade barrier,
increase in international travel, increase in elderly people and immunocompromised
people, and better knowledge of pathogens and regulations for testing foods. Some
are discussed here.
\
II. ASSOCIATED FACTORS
A. Better Knowledge of Pathogens
The etiological agents in foodborne disease outbreaks (and in sporadic incidences)
are not always confirmed. Table 28.2 presents epidemiological data of foodborne
diseases (bacterial, viral, parasitic, and chemical) from four countries — the U.S.
(1960–1987), Canada (1975–1984), the Netherlands (1979–1982), and Croatia
(1986–1992). It is surprising that in the U.S., even in the 1980s, the etiological
agents for 62% of the outbreaks were not identified (also see tables in Chapter 23
to Chapter 26). Similar situations exist in the other three countries. In general, among
etiological agents, bacterial and viral pathogens are the major causes of foodborne
illnesses; many of these with unknown etiology are considered to be of bacterial or
viral origin. In a reported outbreak, when the food and environmental samples and
samples from the patients are available, they are examined for the presence of the
most likely or most common pathogens. Thus, in many incidents, the samples will
usually not be tested for pathogens that are not considered at that time to be a
foodborne pathogen. This is generally the situation with reported sporadic cases or
small outbreaks. In case of a large outbreak or a similar type of outbreak occurring
Table 28.2 Total Foodborne Disease Outbreaks of Unknown Etiology in Several Countries
Period
Outbreaks
(Country)
a Unknown Etiology (%)
Average/Year Range Average/Year Range Ref.
1960–1969b (U.S.)
240 91 to 369 44 13 to 60 1
1970–1979
(U.S.)
409 301 to 497 63 55 to 71 3
1980–1987
(U.S)
531 387 to 656 62 54 to 66 3, 5, 6
1975–1984
(Canada)
867 647 to 1180 78 61 to 84 8
1979–1982
(The
Netherlands)
292 163 to 415 74 71 to 77 9,10
1986–1992
49 72 to 37 87
(Croatia)
c Not
11
available
a Includes outbreaks of bacterial, viral, parasitic, and chemical origin.
b May include a few that were known. In 8 out of 10 years, % unknown ranged from 46 to 60.
c For total number of cases.