410 ◾ Fundamental Food Microbiology
In the future, other pathogens will be recognized as “new” pathogens in the same way. This is
probably true for several pathogens, such as Aeromonas hydrophila, Edwardsiella spp., Plesiomonas
shigelloides, and other opportunistic pathogens, as well as Helicobacter pylori, Mycobacterium paratuberculosis, Clostridium difficile, and several enteric viruses, which have been suspected from circumstantial evidence to be foodborne pathogens but have not yet been directly confirmed.
One of the major reasons for testing available food samples for new pathogens, other than those
tested routinely, is our current expanded knowledge about the characteristics of many pathogens.
Much information is available about different pathogens with respect to their physiological, biochemical, immunological, and genetic characteristics, as well as their pathogenicity, habitat, and
mode of disease transmission. Recent knowledge of entire genome sequences of several pathogens
and advances in molecular biology techniques have greatly aided these studies. This information
has helped develop new, effective, and specific methods to isolate and identify foodborne pathogens from samples. Many of the identification techniques are specific, rapid, and less involved,
even in the presence of large numbers of associated bacteria. This aids in testing, economically
and effectively, a large number of samples in a relatively short span of time for many pathogens,
which includes those routinely tested and those that are probably suspected. Availability of readyto-use kits from commercial sources has advanced this approach. It is anticipated that more new
or emerging pathogens will be added to the list of pathogens of concern in coming years similar to
a new strain of enteroaggregative Escherichia coli (EAEC) O104:H4 that caused one of the largest
outbreaks in Germany and other countries in Europe in 2011 due to consumption of sprouts (see
below).
Improvement in Regulatory Actions
In recent years, at least in most developed countries, the local, state, and federal regulatory agencies have been highly active in reporting a foodborne outbreak and taking quick actions to identify
the etiological agents. The number of reported outbreaks has increased in the United States from
an average of 240 per year in the 1960s to an average of 530 per year in the 1980s. In 2009, there
were 675 outbreaks and in 2010, 852 outbreaks. Norovirus was at the top of the list, responsible
for 42% and Salmonella was second with 30% of outbreaks in 2009 and 2010. 4 This increase is
a result, in large part, of an increase in reporting. Once a new foodborne pathogen is identified,
its frequency of occurrence in foods, mode of transmission in foods, and growth and survival in
foods under conditions of processing, storage, and handling at different stages from production
to consumption are determined. After this information becomes available, regulatory agencies
develop effective methods to either prevent or reduce its presence in the food ready for consumption. This is accomplished by developing proper methods of sanitation during processing and
handling of foods and preservation. For some pathogens, methods to reduce their presence in
raw foods or even in live animals (such as for Esc. coli O157:H7) are being studied. Finally, some
improved efforts have been and are being made by regulatory agencies to educate consumers (especially at home) and food handlers (especially at food service facilities) about the means by which
one can reduce the incidence of contamination (such as for Salmonella from uncooked chicken or
eggs) resulting from cross-contamination and improper cooking or cooling of foods. Public education will need increased focus in order to reduce the incidence of foodborne diseases by pathogens,
including those that are and will become newly emerging. Because foods served at home and at
food service facilities have been implicated in high frequencies of foodborne disease outbreaks,
including those with unknown etiology, people involved in handling food in these two places need
to be aware of the means by which the incidences can be prevented or reduced.
In the future, other pathogens will be recognized as “new” pathogens in the same way. This is
probably true for several pathogens, such as Aeromonas hydrophila, Edwardsiella spp., Plesiomonas
shigelloides, and other opportunistic pathogens, as well as Helicobacter pylori, Mycobacterium paratuberculosis, Clostridium difficile, and several enteric viruses, which have been suspected from circumstantial evidence to be foodborne pathogens but have not yet been directly confirmed.
One of the major reasons for testing available food samples for new pathogens, other than those
tested routinely, is our current expanded knowledge about the characteristics of many pathogens.
Much information is available about different pathogens with respect to their physiological, biochemical, immunological, and genetic characteristics, as well as their pathogenicity, habitat, and
mode of disease transmission. Recent knowledge of entire genome sequences of several pathogens
and advances in molecular biology techniques have greatly aided these studies. This information
has helped develop new, effective, and specific methods to isolate and identify foodborne pathogens from samples. Many of the identification techniques are specific, rapid, and less involved,
even in the presence of large numbers of associated bacteria. This aids in testing, economically
and effectively, a large number of samples in a relatively short span of time for many pathogens,
which includes those routinely tested and those that are probably suspected. Availability of readyto-use kits from commercial sources has advanced this approach. It is anticipated that more new
or emerging pathogens will be added to the list of pathogens of concern in coming years similar to
a new strain of enteroaggregative Escherichia coli (EAEC) O104:H4 that caused one of the largest
outbreaks in Germany and other countries in Europe in 2011 due to consumption of sprouts (see
below).
Improvement in Regulatory Actions
In recent years, at least in most developed countries, the local, state, and federal regulatory agencies have been highly active in reporting a foodborne outbreak and taking quick actions to identify
the etiological agents. The number of reported outbreaks has increased in the United States from
an average of 240 per year in the 1960s to an average of 530 per year in the 1980s. In 2009, there
were 675 outbreaks and in 2010, 852 outbreaks. Norovirus was at the top of the list, responsible
for 42% and Salmonella was second with 30% of outbreaks in 2009 and 2010. 4 This increase is
a result, in large part, of an increase in reporting. Once a new foodborne pathogen is identified,
its frequency of occurrence in foods, mode of transmission in foods, and growth and survival in
foods under conditions of processing, storage, and handling at different stages from production
to consumption are determined. After this information becomes available, regulatory agencies
develop effective methods to either prevent or reduce its presence in the food ready for consumption. This is accomplished by developing proper methods of sanitation during processing and
handling of foods and preservation. For some pathogens, methods to reduce their presence in
raw foods or even in live animals (such as for Esc. coli O157:H7) are being studied. Finally, some
improved efforts have been and are being made by regulatory agencies to educate consumers (especially at home) and food handlers (especially at food service facilities) about the means by which
one can reduce the incidence of contamination (such as for Salmonella from uncooked chicken or
eggs) resulting from cross-contamination and improper cooking or cooling of foods. Public education will need increased focus in order to reduce the incidence of foodborne diseases by pathogens,
including those that are and will become newly emerging. Because foods served at home and at
food service facilities have been implicated in high frequencies of foodborne disease outbreaks,
including those with unknown etiology, people involved in handling food in these two places need
to be aware of the means by which the incidences can be prevented or reduced.