ABSTRACT
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.
