404 ◾ Fundamental Food Microbiology
Cryptosporidium parvum
Cryptosporidium parvum is an intestinal protozoa and causes cryptosporidiosis in humans through
the consumption of contaminated food and water with the oocysts. It can also be present in the
GI tract of domesticated and wild animals and contaminate food and water. The infective dose is
thought to be very low, ~10 oocysts, and the incubation period is 2–10 days. The major symptoms of
infection in humans are watery diarrhea, abdominal pain, fever, muscle aches, dehydration, and, in
some debilitated individuals, such as AIDS patients, death. Cryptosporidium caused the largest waterborne outbreak in Milwaukee, Wisconsin (USA), involving 403,000 cases in 1993. Since then, there
have been four outbreaks in the United States from apple cider, chicken salad, and green onions.
These foods were contaminated with oocysts by the people infected with the protozoa because they
had poor personal hygiene. It is a significant cause of waterborne protozoan disease in humans. The
oocysts are resistant to disinfectants normally used to treat water.
Cyclospora cayetanensis
Cyclospora cayetanensis is a coccidian intestinal protozoan and is considered a newly emerging
foodborne pathogen in the United States. However, the pathogenic nature of the protozoan has
been recognized in many other countries for a long time. Humans and some primates are the only
natural hosts. Consumption of food and water contaminated with the oocysts and subsequent
infection results in the disease. The infective dose is unknown but the incubation period is typically one week. The disease usually lasts for two weeks. The main symptoms are watery diarrhea,
cramps, nausea, vomiting, fever, and fatigue. Since 1995, 80 outbreaks have been reported in the
United States from the consumption of contaminated raspberries, lettuce, and basil. In the late
1990s, contaminated raspberries from Guatemala caused widespread outbreaks in 20 states and
again in 2004; Guatemalan snow peas also caused an outbreak in the United States.
Conclusion
Several bacterial species, normally regarded as nonpathogenic, can cause enteric foodborne disease in susceptible individuals. With the rise in susceptible individuals, there may be more cases
of foodborne diseases in the future. An increase in the consumption of seafood, some raw, has
been regarded as the main cause in the increase of foodborne diseases of fish and shellfish toxins.
Similarly, an increase in the consumption of raw vegetables (salads) and fruits has been related to
the increase in foodborne diseases caused by different parasites. Proper selection of food, sanitation, and processing and preservation methods can be used to reduce their incidence in food.
QUESTIONS
1. Define an opportunistic pathogen. Briefly explain how Aer. hydrophila can be considered an
opportunistic pathogen.
2. Briefly discuss the possibility of causing foodborne gastroenteritis by Ple. shigelloides.
3. Name three noncoliforms that may be associated with human foodborne gastroenteritis.
What evidence can be given to justify them as the causative agents for gastroenteritis?
4. Discuss the importance of psychrotrophic Bacillus spp. as a possible causative agent for foodborne gastroenteritis. Why can the consumption of pasteurized milk stored in the refrigerator for a long time be associated with gastroenteritis caused by psychrotrophic Bacillus spp.?
Cryptosporidium parvum
Cryptosporidium parvum is an intestinal protozoa and causes cryptosporidiosis in humans through
the consumption of contaminated food and water with the oocysts. It can also be present in the
GI tract of domesticated and wild animals and contaminate food and water. The infective dose is
thought to be very low, ~10 oocysts, and the incubation period is 2–10 days. The major symptoms of
infection in humans are watery diarrhea, abdominal pain, fever, muscle aches, dehydration, and, in
some debilitated individuals, such as AIDS patients, death. Cryptosporidium caused the largest waterborne outbreak in Milwaukee, Wisconsin (USA), involving 403,000 cases in 1993. Since then, there
have been four outbreaks in the United States from apple cider, chicken salad, and green onions.
These foods were contaminated with oocysts by the people infected with the protozoa because they
had poor personal hygiene. It is a significant cause of waterborne protozoan disease in humans. The
oocysts are resistant to disinfectants normally used to treat water.
Cyclospora cayetanensis
Cyclospora cayetanensis is a coccidian intestinal protozoan and is considered a newly emerging
foodborne pathogen in the United States. However, the pathogenic nature of the protozoan has
been recognized in many other countries for a long time. Humans and some primates are the only
natural hosts. Consumption of food and water contaminated with the oocysts and subsequent
infection results in the disease. The infective dose is unknown but the incubation period is typically one week. The disease usually lasts for two weeks. The main symptoms are watery diarrhea,
cramps, nausea, vomiting, fever, and fatigue. Since 1995, 80 outbreaks have been reported in the
United States from the consumption of contaminated raspberries, lettuce, and basil. In the late
1990s, contaminated raspberries from Guatemala caused widespread outbreaks in 20 states and
again in 2004; Guatemalan snow peas also caused an outbreak in the United States.
Conclusion
Several bacterial species, normally regarded as nonpathogenic, can cause enteric foodborne disease in susceptible individuals. With the rise in susceptible individuals, there may be more cases
of foodborne diseases in the future. An increase in the consumption of seafood, some raw, has
been regarded as the main cause in the increase of foodborne diseases of fish and shellfish toxins.
Similarly, an increase in the consumption of raw vegetables (salads) and fruits has been related to
the increase in foodborne diseases caused by different parasites. Proper selection of food, sanitation, and processing and preservation methods can be used to reduce their incidence in food.
QUESTIONS
1. Define an opportunistic pathogen. Briefly explain how Aer. hydrophila can be considered an
opportunistic pathogen.
2. Briefly discuss the possibility of causing foodborne gastroenteritis by Ple. shigelloides.
3. Name three noncoliforms that may be associated with human foodborne gastroenteritis.
What evidence can be given to justify them as the causative agents for gastroenteritis?
4. Discuss the importance of psychrotrophic Bacillus spp. as a possible causative agent for foodborne gastroenteritis. Why can the consumption of pasteurized milk stored in the refrigerator for a long time be associated with gastroenteritis caused by psychrotrophic Bacillus spp.?