316 ◾ Fundamental Food Microbiology
frequency of foodborne disease outbreaks with foods from large commercial processors is low. This
is generally because of their use of good quality control, sanitation, and testing of the products for
the pathogens. However, when a contamination of food by a pathogen occurs in a big processing
establishment, a large number of people over a wide area are affected. 9
Predominant Contributing Factors Associated with Confirmed
Foodborne Disease Outbreaks from Pathogenic Bacteria and Viruses
Before consumption, foods are exposed to many different environments and conditions. These
dictate whether a pathogen present initially will survive or be killed, whether recontamination can
occur, or whether a pathogen can multiply to reach a high population to cause disease. The foodborne disease outbreak data between 1983 and 1987 in the United States revealed that the most
predominant cause of the outbreaks was improper holding (refrigerated) temperature of the food,
which was responsible for 34.6% outbreaks. The temperature abuse resulted in the growth of
pathogens (bacteria) reaching a level that causes illness following consumption. The other factors,
in order of importance, were contamination of foods resulting from poor personal hygiene (20.5%
outbreak), survival of pathogens after cooking at lower temperatures than specified (16.7%), crosscontamination of foods from equipment (previously contaminated with pathogens) (15.3%), and
food from unsafe sources, such as raw foods (5.5%). These five factors, in combination, were
responsible for 92.6% of the outbreaks caused by pathogenic bacteria and viruses. 9
Influence of Month (of the Year) to Number of Foodborne Disease
Outbreaks Caused by Pathogenic Bacteria and Viruses
In general, foodborne outbreaks of pathogenic bacterial and viral origin are more prevalent during
the summer months. The compiled data between 1983 and 1987 show that in the United States
about 66% of the outbreaks occurred during May to September with the highest incidence in
August. 9 Between November and April, the incidence was reduced to about 34%. During commercial processing, the food products are exposed to indoor temperatures, which may not vary
greatly in the summer or the winter. However, both raw products and processed products could
be exposed to outside temperatures for a long time during transportation, displays in retail stores,
at food establishments, and at home. Also, during the summer, picnics and outdoor eating occur
more frequently. A high temperature during the summer can stimulate rapid growth of the contaminating pathogens, reaching high levels, even from a low initial level, within a relatively shorter
period. During the winter months, the growth rate can be greatly reduced; fewer outbreaks are
reported to occur during February.
Influence of Location on Foodborne Diseases of
Pathogenic Bacterial and Viral Origin
It has been mentioned previously that, in general, the incidence of foodborne disease outbreaks is
lower in the developed countries than in the developing countries. Several socioeconomic reasons
and climatic conditions have major roles in this difference. However, the frequency of outbreaks
can vary greatly among regions, both in the developed and developing countries. In the United
States, foodborne disease outbreaks have been recorded more frequently in some states than in
others. States with high populations, large numbers of industry, and warm climates have more
frequency of foodborne disease outbreaks with foods from large commercial processors is low. This
is generally because of their use of good quality control, sanitation, and testing of the products for
the pathogens. However, when a contamination of food by a pathogen occurs in a big processing
establishment, a large number of people over a wide area are affected. 9
Predominant Contributing Factors Associated with Confirmed
Foodborne Disease Outbreaks from Pathogenic Bacteria and Viruses
Before consumption, foods are exposed to many different environments and conditions. These
dictate whether a pathogen present initially will survive or be killed, whether recontamination can
occur, or whether a pathogen can multiply to reach a high population to cause disease. The foodborne disease outbreak data between 1983 and 1987 in the United States revealed that the most
predominant cause of the outbreaks was improper holding (refrigerated) temperature of the food,
which was responsible for 34.6% outbreaks. The temperature abuse resulted in the growth of
pathogens (bacteria) reaching a level that causes illness following consumption. The other factors,
in order of importance, were contamination of foods resulting from poor personal hygiene (20.5%
outbreak), survival of pathogens after cooking at lower temperatures than specified (16.7%), crosscontamination of foods from equipment (previously contaminated with pathogens) (15.3%), and
food from unsafe sources, such as raw foods (5.5%). These five factors, in combination, were
responsible for 92.6% of the outbreaks caused by pathogenic bacteria and viruses. 9
Influence of Month (of the Year) to Number of Foodborne Disease
Outbreaks Caused by Pathogenic Bacteria and Viruses
In general, foodborne outbreaks of pathogenic bacterial and viral origin are more prevalent during
the summer months. The compiled data between 1983 and 1987 show that in the United States
about 66% of the outbreaks occurred during May to September with the highest incidence in
August. 9 Between November and April, the incidence was reduced to about 34%. During commercial processing, the food products are exposed to indoor temperatures, which may not vary
greatly in the summer or the winter. However, both raw products and processed products could
be exposed to outside temperatures for a long time during transportation, displays in retail stores,
at food establishments, and at home. Also, during the summer, picnics and outdoor eating occur
more frequently. A high temperature during the summer can stimulate rapid growth of the contaminating pathogens, reaching high levels, even from a low initial level, within a relatively shorter
period. During the winter months, the growth rate can be greatly reduced; fewer outbreaks are
reported to occur during February.
Influence of Location on Foodborne Diseases of
Pathogenic Bacterial and Viral Origin
It has been mentioned previously that, in general, the incidence of foodborne disease outbreaks is
lower in the developed countries than in the developing countries. Several socioeconomic reasons
and climatic conditions have major roles in this difference. However, the frequency of outbreaks
can vary greatly among regions, both in the developed and developing countries. In the United
States, foodborne disease outbreaks have been recorded more frequently in some states than in
others. States with high populations, large numbers of industry, and warm climates have more