Important Facts in Foodborne Diseases ◾ 313
Toxico-Infection
Illness occurs from the ingestion of a large number of viable cells of some pathogenic bacteria
through contaminated food and water. Generally, the bacterial cells sporulate, colonize, or die and
release toxin(s) to produce the symptoms (e.g., Clo. perfringens gastroenteritis).
In addition to the pathogenic microorganisms associated with foodborne illnesses, there are
some bacterial species and strains, normally considered nonpathogenic, that are capable of causing gastroenteritis, especially in susceptible individuals. They are designated as opportunistic
pathogens. They are normally required to be alive and present in large numbers when consumed
through a contaminated food.
Predominant Food Types Associated with Foodborne
Diseases of Bacterial and Viral Origin
Certain food types or foods prepared under specific conditions and environments have been
implicated more frequently with foodborne disease than others. Some of the factors could be the
presence of a pathogen in the raw materials in higher frequency with a greater chance of contamination of the finished products, the ability of a pathogen to grow advantageously in a particular
type of food, a greater chance of failure in quality control in a specific environment, and a higher
possibility of contaminating the finished products by food handlers. Some of these aspects can
be explained from the foodborne disease outbreak data presented in Table 24.5. Foods of animal
origin (meat, fish, eggs, and dairy products), fresh fruits and vegetables, nuts, and spices are major
source for outbreaks in recent years. However, the general trend for outbreaks in recent years
is associated more with fresh produce involving lettuce, sprouts, cantaloupes, etc. The primary
pathogens involved in many of these outbreaks are Salmonella, Esc. coli, Listeria, and norovirus. 6–8 Salmonella serovars were involved in a large proportion of the outbreaks because many
food animals harbor Salmonella as carriers in the digestive tract and thus can contaminate meat,
eggs, and dairy products and the environment. Peanuts and peanut butter and spices were also
involved with several Salmonella outbreaks, possibly resulting from contamination from birds or
environmental sources. Processed fish, especially those that are smoked, are found to contain large
numbers of Lis. monocytogenes. In recent years, fish consumption has increased, and foodborne
disease outbreaks from fishery products have also increased. Similarly, fruits and vegetables can be
contaminated with Esc. coli, Lis. Monocytogenes, and Salmonella from untreated manure/fertilizer
of animal origin, irrigation water, and the soil. In contrast, salads, which are handled extensively,
can be contaminated with several pathogens of human origin. The high incidence of Clo. perfringens in Mexican foods and Bac. cereus in Chinese fried rice or pasta is likely a result of the methods
used in the preparation of certain ethnic foods. Ready-to-eat processed lunchmeats (bologna,
hotdogs) and soft cheeses made with unpasteurized milk (e.g., Mexican-style soft cheese) have
high incidences of Lis. monocytogenes. However, one can speculate from the high incidence of
Salmonella in both multiple foods and unknown food categories that many were probably foods
of animal origin.
Predominant Places of Food Consumption Associated with Confirmed
Foodborne Disease Outbreaks of Bacterial and Viral Origin
An analysis of the relationship between the places of food consumption and the number of
foodborne disease outbreaks revealed that, at least in the United States, the highest number of
Toxico-Infection
Illness occurs from the ingestion of a large number of viable cells of some pathogenic bacteria
through contaminated food and water. Generally, the bacterial cells sporulate, colonize, or die and
release toxin(s) to produce the symptoms (e.g., Clo. perfringens gastroenteritis).
In addition to the pathogenic microorganisms associated with foodborne illnesses, there are
some bacterial species and strains, normally considered nonpathogenic, that are capable of causing gastroenteritis, especially in susceptible individuals. They are designated as opportunistic
pathogens. They are normally required to be alive and present in large numbers when consumed
through a contaminated food.
Predominant Food Types Associated with Foodborne
Diseases of Bacterial and Viral Origin
Certain food types or foods prepared under specific conditions and environments have been
implicated more frequently with foodborne disease than others. Some of the factors could be the
presence of a pathogen in the raw materials in higher frequency with a greater chance of contamination of the finished products, the ability of a pathogen to grow advantageously in a particular
type of food, a greater chance of failure in quality control in a specific environment, and a higher
possibility of contaminating the finished products by food handlers. Some of these aspects can
be explained from the foodborne disease outbreak data presented in Table 24.5. Foods of animal
origin (meat, fish, eggs, and dairy products), fresh fruits and vegetables, nuts, and spices are major
source for outbreaks in recent years. However, the general trend for outbreaks in recent years
is associated more with fresh produce involving lettuce, sprouts, cantaloupes, etc. The primary
pathogens involved in many of these outbreaks are Salmonella, Esc. coli, Listeria, and norovirus. 6–8 Salmonella serovars were involved in a large proportion of the outbreaks because many
food animals harbor Salmonella as carriers in the digestive tract and thus can contaminate meat,
eggs, and dairy products and the environment. Peanuts and peanut butter and spices were also
involved with several Salmonella outbreaks, possibly resulting from contamination from birds or
environmental sources. Processed fish, especially those that are smoked, are found to contain large
numbers of Lis. monocytogenes. In recent years, fish consumption has increased, and foodborne
disease outbreaks from fishery products have also increased. Similarly, fruits and vegetables can be
contaminated with Esc. coli, Lis. Monocytogenes, and Salmonella from untreated manure/fertilizer
of animal origin, irrigation water, and the soil. In contrast, salads, which are handled extensively,
can be contaminated with several pathogens of human origin. The high incidence of Clo. perfringens in Mexican foods and Bac. cereus in Chinese fried rice or pasta is likely a result of the methods
used in the preparation of certain ethnic foods. Ready-to-eat processed lunchmeats (bologna,
hotdogs) and soft cheeses made with unpasteurized milk (e.g., Mexican-style soft cheese) have
high incidences of Lis. monocytogenes. However, one can speculate from the high incidence of
Salmonella in both multiple foods and unknown food categories that many were probably foods
of animal origin.
Predominant Places of Food Consumption Associated with Confirmed
Foodborne Disease Outbreaks of Bacterial and Viral Origin
An analysis of the relationship between the places of food consumption and the number of
foodborne disease outbreaks revealed that, at least in the United States, the highest number of