Important Facts in Foodborne Diseases ◾ 317
incidences. Some of the states in this group are New York, Washington, California, Hawaii, and
Pennsylvania. Some other factors, such as a large ethnic population, greater frequency of migration and traveling of people, as well as better surveillance systems, could also be the reasons for
the high incidence rate. In comparison, states with lower populations had very few incidents.
Imported foods from countries around the globe were also responsible for foodborne outbreaks
in the United States. In 2013, the CDC, based on the data collected from 2005 to 2010 reported
that imported foods from 15 countries were responsible for 39 outbreaks involving 2348 illnesses
in the United States (see Chapter 29). 10
Human Factors in Foodborne Disease Symptoms
When a group of people consumes food contaminated with live cells of pathogens or their toxins, it does not make everybody develop disease symptoms. 9 Also, among those who develop the
symptoms, all may not show either the same symptoms or the same severity of any symptom. This
is probably a result of the difference in resistance among individuals. One of the factors involved
in developing symptoms from the consumption of a contaminated food is susceptibility of an
individual to the contaminants. In general, infants and old, sick, pregnant, and immunodeficient
people (e.g., AIDS patients) are more susceptible than normal adults and healthy individuals. The
chance of developing disease symptoms is directly related to the amount of a contaminated food
consumed. This is related to the number of viable cells of a pathogen or the amount of a toxin
consumed by an individual. The virulence of a pathogen or a toxin consumed through a food also
determines the onset of a disease and severity of symptoms. For some highly virulent pathogens,
such as Esc. coli serovar O157:H7, O104:H4 consumption of as low as 10 viable cells can cause
disease in an infant. In contrast, for some pathogens, such as Yersinia enterocolitica, consumption
of as high as 1 million or more viable cells is necessary for the symptoms to develop.
Acceptance Quality of Food Resulting from Growth of Pathogens
Pathogenic viruses and protozoan parasites need viable host cells for growth; thus, in prepared
foods, they cannot grow, and they do not affect the food quality. Pathogenic bacteria can grow in
many foods. When the environment is suitable, only a few viable cells present initially can reach
a high level, maybe several millions per gram or milliliter. However, growth of some pathogens,
even to a high level, may not alter the color, texture, and odor of a food (such as Sta. aureus). People
can consume this food without suspicion and develop symptoms of a foodborne illness.
Sequence of Events in a Foodborne Disease
For a foodborne disease to occur, several events have to happen in sequence (Figure 24.2). 9 An
understanding of these sequences is helpful in investigating the cause (the source and means of
transmission) of a foodborne disease. It also helps in recognizing how the sequence can be broken
in order to stop a foodborne disease. Initially, there has to be a source of a pathogen. Next, the
pathogen has to contaminate a food. Consumption of the food contaminated with a pathogenic
virus or parasites may lead to viral or parasitic infection. For bacterial pathogens (and toxicogenic
molds), the contaminated food has to support growth and be exposed for a certain period of time
at a suitable temperature to enable the pathogens to grow. However, for some potent pathogens
(such as Esc. coli O157:H7) growth may not be necessary to cause a foodborne infection. For
intoxication, the growth should reach a sufficient level to produce enough toxins so that when
incidences. Some of the states in this group are New York, Washington, California, Hawaii, and
Pennsylvania. Some other factors, such as a large ethnic population, greater frequency of migration and traveling of people, as well as better surveillance systems, could also be the reasons for
the high incidence rate. In comparison, states with lower populations had very few incidents.
Imported foods from countries around the globe were also responsible for foodborne outbreaks
in the United States. In 2013, the CDC, based on the data collected from 2005 to 2010 reported
that imported foods from 15 countries were responsible for 39 outbreaks involving 2348 illnesses
in the United States (see Chapter 29). 10
Human Factors in Foodborne Disease Symptoms
When a group of people consumes food contaminated with live cells of pathogens or their toxins, it does not make everybody develop disease symptoms. 9 Also, among those who develop the
symptoms, all may not show either the same symptoms or the same severity of any symptom. This
is probably a result of the difference in resistance among individuals. One of the factors involved
in developing symptoms from the consumption of a contaminated food is susceptibility of an
individual to the contaminants. In general, infants and old, sick, pregnant, and immunodeficient
people (e.g., AIDS patients) are more susceptible than normal adults and healthy individuals. The
chance of developing disease symptoms is directly related to the amount of a contaminated food
consumed. This is related to the number of viable cells of a pathogen or the amount of a toxin
consumed by an individual. The virulence of a pathogen or a toxin consumed through a food also
determines the onset of a disease and severity of symptoms. For some highly virulent pathogens,
such as Esc. coli serovar O157:H7, O104:H4 consumption of as low as 10 viable cells can cause
disease in an infant. In contrast, for some pathogens, such as Yersinia enterocolitica, consumption
of as high as 1 million or more viable cells is necessary for the symptoms to develop.
Acceptance Quality of Food Resulting from Growth of Pathogens
Pathogenic viruses and protozoan parasites need viable host cells for growth; thus, in prepared
foods, they cannot grow, and they do not affect the food quality. Pathogenic bacteria can grow in
many foods. When the environment is suitable, only a few viable cells present initially can reach
a high level, maybe several millions per gram or milliliter. However, growth of some pathogens,
even to a high level, may not alter the color, texture, and odor of a food (such as Sta. aureus). People
can consume this food without suspicion and develop symptoms of a foodborne illness.
Sequence of Events in a Foodborne Disease
For a foodborne disease to occur, several events have to happen in sequence (Figure 24.2). 9 An
understanding of these sequences is helpful in investigating the cause (the source and means of
transmission) of a foodborne disease. It also helps in recognizing how the sequence can be broken
in order to stop a foodborne disease. Initially, there has to be a source of a pathogen. Next, the
pathogen has to contaminate a food. Consumption of the food contaminated with a pathogenic
virus or parasites may lead to viral or parasitic infection. For bacterial pathogens (and toxicogenic
molds), the contaminated food has to support growth and be exposed for a certain period of time
at a suitable temperature to enable the pathogens to grow. However, for some potent pathogens
(such as Esc. coli O157:H7) growth may not be necessary to cause a foodborne infection. For
intoxication, the growth should reach a sufficient level to produce enough toxins so that when