407
Chapter 29
new and emerging
Foodborne Pathogens
introduction
A comparison of the lists of bacteria and viruses that were known to be foodborne pathogens in
the past and those confirmed as foodborne pathogens currently reveals quite an astonishing picture.
Many that were not considered or known to be foodborne pathogens in the past have later been implicated in foodborne illnesses. These pathogens, following their recognition, are generally designated
as new or emerging foodborne pathogens. Table 29.1 presents a list of pathogens recognized as new
foodborne pathogens during the past 30 years in the United States. Before 1959, four bacterial species
were considered as foodborne pathogens: Staphylococcus aureus; Salmonella enterica serovars, including
Typhi and Paratyphi; Clostridium botulinum Types A and B; and Shigella spp. In the 1960s, Vibrio
cholerae non-O1 and Clo. botulinum Type E were added to the list of bacteria, along with hepatitis A
virus. Between 1971 and 1980, Vibrio parahaemolyticus, enteropathogenic Escherichia coli (O124:H17),
Yersinia enterocolitica, Vib. cholerae O1, Campylobacter jejuni, and Vib. vulnificus were confirmed either
in foodborne disease outbreaks or sporadic cases. The food association of Clo. botulinum with infant
botulism was also recognized. In the 1980s and 1990s, Listeria monocytogenes, enterohemorrhagenic
Esc. coli O157:H7, enterotoxigenic Esc. coli O27:H20, Norovirus, and Campylobacter, Cryptosporidium,
and Cyclospora became the new pathogens. Salmonella enterica ser. Enteritidis, which was earlier
involved in foodborne outbreaks in a relatively low frequency, became a major causative agent of
foodborne salmonellosis. In recent years, the possible role of several pathogens, namely, Clostridium
difficile, Cronobacter sakazaki, Helicobacter pylori, Mycobacterium paratuberculosis, and a few enteric
viruses in foodborne/waterborne diseases has been suspected. Similar situations involving the sudden
emergence of new foodborne pathogens with time also exist in other countries.
Are they really “new” foodborne pathogens? If a pathogen uses a food as a vehicle for its transmission to humans for the first time and causes the specific illness, then it is probably not new. Rather,
it is appropriate to recognize that it probably has caused foodborne illnesses before but has not been
confirmed. Because of changes in several situations, its direct involvement in a foodborne illness has
probably been suspected before and identified later for the first time. In this section, the changes in
several situations that have probably led to the discovery of a new foodborne pathogen are discussed.
Chapter 29
new and emerging
Foodborne Pathogens
introduction
A comparison of the lists of bacteria and viruses that were known to be foodborne pathogens in
the past and those confirmed as foodborne pathogens currently reveals quite an astonishing picture.
Many that were not considered or known to be foodborne pathogens in the past have later been implicated in foodborne illnesses. These pathogens, following their recognition, are generally designated
as new or emerging foodborne pathogens. Table 29.1 presents a list of pathogens recognized as new
foodborne pathogens during the past 30 years in the United States. Before 1959, four bacterial species
were considered as foodborne pathogens: Staphylococcus aureus; Salmonella enterica serovars, including
Typhi and Paratyphi; Clostridium botulinum Types A and B; and Shigella spp. In the 1960s, Vibrio
cholerae non-O1 and Clo. botulinum Type E were added to the list of bacteria, along with hepatitis A
virus. Between 1971 and 1980, Vibrio parahaemolyticus, enteropathogenic Escherichia coli (O124:H17),
Yersinia enterocolitica, Vib. cholerae O1, Campylobacter jejuni, and Vib. vulnificus were confirmed either
in foodborne disease outbreaks or sporadic cases. The food association of Clo. botulinum with infant
botulism was also recognized. In the 1980s and 1990s, Listeria monocytogenes, enterohemorrhagenic
Esc. coli O157:H7, enterotoxigenic Esc. coli O27:H20, Norovirus, and Campylobacter, Cryptosporidium,
and Cyclospora became the new pathogens. Salmonella enterica ser. Enteritidis, which was earlier
involved in foodborne outbreaks in a relatively low frequency, became a major causative agent of
foodborne salmonellosis. In recent years, the possible role of several pathogens, namely, Clostridium
difficile, Cronobacter sakazaki, Helicobacter pylori, Mycobacterium paratuberculosis, and a few enteric
viruses in foodborne/waterborne diseases has been suspected. Similar situations involving the sudden
emergence of new foodborne pathogens with time also exist in other countries.
Are they really “new” foodborne pathogens? If a pathogen uses a food as a vehicle for its transmission to humans for the first time and causes the specific illness, then it is probably not new. Rather,
it is appropriate to recognize that it probably has caused foodborne illnesses before but has not been
confirmed. Because of changes in several situations, its direct involvement in a foodborne illness has
probably been suspected before and identified later for the first time. In this section, the changes in
several situations that have probably led to the discovery of a new foodborne pathogen are discussed.