366 ◾ Fundamental Food Microbiology
be present. Some strains can cause scarlet fever. 45 Foodborne infections have been recorded from
the consumption of contaminated raw milk and milk products made with raw milk and different types of salads (contaminated by infected food handlers). In the United States, between 1983
and 1987, seven outbreaks affected 1019 individuals. In one outbreak in 1983, 553 people were
affected from eating a contaminated potato salad. According to 2011 report, Group A streptococci
is responsible for about 11,200 illnesses each year in the United States. 29 In addition to Group
A streptococci, some other streptococci have been implicated in foodborne infections. Control
measures include pasteurization of dairy products and avoiding the consumption of raw milk and
products made with raw milk. People who are suffering from streptococcal infections or are carriers should not handle ready-to-eat foods such as salads. Proper sanitation in all phases of processing and proper refrigeration will help reduce the incidence.
Q Fever
Q fever in humans is caused by a unique bacterium (rickettsia), Coxiella burnetii. Animals carry
this organism without any symptom. People handling animals, raw milk, and meat can be
infected by the rickettsia and develop symptoms of Q fever. Symptoms include fever, malaise,
anorexia, muscular pain, and headache. Symptoms appear two to four weeks after infection and
last for approximately two weeks. Foodborne infection occurs from the consumption of raw or
improperly pasteurized milk and milk products. Cox. burnetii is more resistant to heat than many
pathogenic bacteria. Because of this, the current temperature and time of pasteurization of milk
have been set to either 145°F (62.8°C) for 30 minutes or 160°F (71.1°C) for 15 seconds so that
Cox. burnetii is killed. Recently (in 2011), consumption of raw milk in Michigan (United States)
resulted in a Cox. burnetii outbreak that infected five people. 46
Conclusion
Foodborne infection is caused by several enteric pathogenic bacteria. The viable cells survive the
GI environment and set up infection in the intestine to produce enteric symptoms and fever.
Several can also infect the organs inside the body and produce specific diseases. Several pathogens of this group can also produce a high rate of mortality. All of them are sensitive to low heat
and killed by pasteurization. Proper sanitation, heat treatment, and refrigeration can be adopted
to reduce their incidence. However, a few can multiply even at 1°C; to overcome problems from
them, foods should not be refrigerated for a long time and a refrigerated food should be reheated
uniformly before consumption.
QUESTIONS
1. List some characteristics of foodborne microbial infections. Define enteric and nonenteric
infections and give examples of three pathogens in each group.
2. How do symptoms of foodborne infection, intoxication, and toxico-infection differ?
3. Explain the possible reasons for the current increase in foodborne salmonellosis in a developed country.
4. Briefly discuss the current scheme used in the taxonomy of Salmonella serovars.
5. Discuss the regulatory requirements and suggestions directed to control foodborne salmonellosis in the United States.
be present. Some strains can cause scarlet fever. 45 Foodborne infections have been recorded from
the consumption of contaminated raw milk and milk products made with raw milk and different types of salads (contaminated by infected food handlers). In the United States, between 1983
and 1987, seven outbreaks affected 1019 individuals. In one outbreak in 1983, 553 people were
affected from eating a contaminated potato salad. According to 2011 report, Group A streptococci
is responsible for about 11,200 illnesses each year in the United States. 29 In addition to Group
A streptococci, some other streptococci have been implicated in foodborne infections. Control
measures include pasteurization of dairy products and avoiding the consumption of raw milk and
products made with raw milk. People who are suffering from streptococcal infections or are carriers should not handle ready-to-eat foods such as salads. Proper sanitation in all phases of processing and proper refrigeration will help reduce the incidence.
Q Fever
Q fever in humans is caused by a unique bacterium (rickettsia), Coxiella burnetii. Animals carry
this organism without any symptom. People handling animals, raw milk, and meat can be
infected by the rickettsia and develop symptoms of Q fever. Symptoms include fever, malaise,
anorexia, muscular pain, and headache. Symptoms appear two to four weeks after infection and
last for approximately two weeks. Foodborne infection occurs from the consumption of raw or
improperly pasteurized milk and milk products. Cox. burnetii is more resistant to heat than many
pathogenic bacteria. Because of this, the current temperature and time of pasteurization of milk
have been set to either 145°F (62.8°C) for 30 minutes or 160°F (71.1°C) for 15 seconds so that
Cox. burnetii is killed. Recently (in 2011), consumption of raw milk in Michigan (United States)
resulted in a Cox. burnetii outbreak that infected five people. 46
Conclusion
Foodborne infection is caused by several enteric pathogenic bacteria. The viable cells survive the
GI environment and set up infection in the intestine to produce enteric symptoms and fever.
Several can also infect the organs inside the body and produce specific diseases. Several pathogens of this group can also produce a high rate of mortality. All of them are sensitive to low heat
and killed by pasteurization. Proper sanitation, heat treatment, and refrigeration can be adopted
to reduce their incidence. However, a few can multiply even at 1°C; to overcome problems from
them, foods should not be refrigerated for a long time and a refrigerated food should be reheated
uniformly before consumption.
QUESTIONS
1. List some characteristics of foodborne microbial infections. Define enteric and nonenteric
infections and give examples of three pathogens in each group.
2. How do symptoms of foodborne infection, intoxication, and toxico-infection differ?
3. Explain the possible reasons for the current increase in foodborne salmonellosis in a developed country.
4. Briefly discuss the current scheme used in the taxonomy of Salmonella serovars.
5. Discuss the regulatory requirements and suggestions directed to control foodborne salmonellosis in the United States.