Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MICR3215: Food Microbiology and Biotechnology > Foodborne Pathogens - Fungi and Viruses > Flashcards

Foodborne Pathogens - Fungi and Viruses Flashcards

1
Q

What is the characteristic feature of viruses when it comes to multiplication?

A

Viruses multiply only in living cells (hosts) and are fairly hard to kill while in humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Can viruses replicate in food?

A

No, viruses do not replicate in food.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are viruses usually killed?

A

Viruses are usually killed during the cooking process.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How can food become contaminated with viruses after cooking?

A

Food may become contaminated after cooking by human carriers or by contaminated water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are some examples of viruses?

A
  • Hepatitis A
  • Norwalk Virus,
  • Rotavirus,
  • Adenovirus.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the typical mode of infection for enteric viruses?

A

Enteric viruses generally infect subsequent to ingestion and are shed in faeces.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Do viruses primarily have human hosts?

A

Viruses have human hosts, but animal hosts are possible. However, animal hosts are either unknown or of no particular significance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which part of the body is mainly affected by viruses?

A

The principal site of action for viruses is the lining of the small intestine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does disease result from viral infections?

A

Disease results from either the killing of infected cells by the viral replicative process or from the destruction of infected cells by the host’s immune response.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the structure of the Hepatitis A virus?

A
  • gram-negative sense single-stranded RNA virus lacking an envelope.
  • It appears similar to other picornaviruses with a diameter of approximately 28 nm
  • has a spherical shape with smooth surfaces.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can the presence of the Hepatitis A virus be detected?

A
  • RT-PCR,
  • ELISA,
  • other serological tests.
  • Diagnosis is usually based on symptoms, elevated liver enzymes, and the detection of anti-HAV IgM antibodies in the serum.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is Hepatitis A transmitted?

A
  • through the faecal-oral route.
  • The main reservoir is human faeces.
  • It can be contracted through contaminated food sources such as water, ice, shellfish, cold cuts, sandwiches, milk, dairy products, and fruits and vegetables washed with infected water or contaminated by infected humans or animals.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the symptoms of Hepatitis A?

A
  • discomfort,
  • fatigue,
  • headache,
  • nausea,
  • loss of appetite,
  • vomiting,
  • abdominal pain,
  • dark urine,
  • jaundice.
  • These symptoms may appear weeks or months after exposure. The incubation period for Hepatitis A is 15 to 45 days.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How can Hepatitis A be controlled?

A

Hepatitis A can be controlled through:
1. vaccination,
2. good personal hygiene including handwashing, proper sanitation and water treatment to reduce the risk of contamination
3. cooking food to proper temperatures to kill the virus.
4. It is also advised to avoid consuming raw or undercooked shellfish or other potentially contaminated foods.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the characteristics of the Hepatitis E virus?

A
  • looks like caliciviruses with a diameter of approximately 32 nm.
  • It is spherical and has visible cup-shaped concavities on its surfaces.
  • HEV is a non-enveloped virus with ssRNA.
  • It is endemic to areas of poor sanitation, especially in developing countries.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How can the presence of the Hepatitis E virus be detected?

A
  • RT-PCR,
  • ELISA,
  • other serological tests.
  • Diagnosis is usually based on symptoms, elevated liver enzymes, and the detection of anti-HEV IgM antibodies in the serum.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is Hepatitis E transmitted?

A
  • transmitted through the faecal-oral route.
  • Contaminated water or food, including undercooked or raw pork, deer, and wild boar meat, can serve as sources of transmission.
  • Hepatitis E virus is endemic to areas with poor sanitation, especially in developing countries.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the symptoms of Hepatitis E?

A
  • anorexia,
  • vomiting,
  • profound malaise.
  • The incubation period ranges from 2 to 10 weeks.
  • HEV can cause both sporadic and epidemic outbreaks, especially in developing countries with poor sanitation.
  • It can cause severe illness and death, particularly in pregnant women.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How can Hepatitis E be controlled?

A
  1. proper sanitation and water treatment to reduce the risk of contamination,
  2. cooking food to proper temperatures to kill the virus,
  3. Avoid the consumption of raw or undercooked pork, deer, and wild boar meat.
  4. While an HEV vaccine is available in some countries, it is not widely used.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the main characteristics of Norovirus?

A
  • an unenveloped, positive-sense single-stranded RNA virus
  • a diameter of 23-40 nm.
  • genome consists of nonstructural proteins such as ORF1, VP1 capsid protein (ORF2), and a phosphorylated VP2 protein (ORF3).
  • particles can survive at low pH (2-4)
  • emerging virulent strains may cause death in elderly and immunocompromised patients.
21
Q

How is Norovirus diagnosed or detected?

A

PCR (polymerase chain reaction) and EIA (enzyme immunoassay) tests.

22
Q

What are the sources of contamination of Norovirus?

A
  • commonly found on cruise ships and in-care facilities.
  • transmitted through the faecal-oral route, often due to poor personal hygiene or contaminated water.
  • Food sources such as water, shellfish, and raw fruits and vegetables washed with infected water or contaminated by infected humans or animals can also transmit the virus.
23
Q

What are the diseases/symptoms associated with Norovirus?

A
  1. nausea,
  2. vomiting,
  3. diarrhoea,
  4. abdominal cramps,
  5. headache, and mild fever.

-The incubation period is 18 to 48 hours, and the duration of symptoms usually ranges from 24-72 hours.

24
Q

How can Norovirus be controlled?

A
  • can be inactivated by disinfection with chlorine. However, they are more resistant to chlorine disinfection than the Hepatitis A virus and can withstand 5-6 ppm (parts per million) of chlorine.
  • Control measures include:
    1. ensuring good personal hygiene practices among food handlers,
    2. thoroughly cooking food to minimum safe internal temperatures, 3. using approved water sources.
25
Q

What are the main characteristics of Astroviruses?

A
  • small,
  • round,
  • structured viruses with a raised, 5-6 pointed star pattern on the protein coat surface.
  • Their nucleic acid is a single strand of RNA.
26
Q

How are Astroviruses diagnosed or detected?

A
  • PCR (polymerase chain reaction) and EIA (enzyme immunoassay) tests.
  • Several serotypes of Astrovirus are able to infect laboratory cell cultures and cause cytopathic effects.
27
Q

What are the sources of contamination for Astroviruses? What are the risk groups?

A
  • Foods
  • Risk groups are the young and the elderly.
28
Q

What are the diseases associated with Astroviruses?

A
  • The infectious dose of Astrovirus is less than 100 virus particles.
  • Symptoms include diarrhea (more typical than vomiting) with an incubation period of 3-4 days.
  • The duration of illness is 2-3 days.
  • Astrovirus infects and kills mature enterocytes on the villi of the small intestine.
29
Q

How can Astroviruses be controlled?

A
  1. ensure that food handlers practice good personal hygiene,
  2. thoroughly cook food to minimum safe internal temperatures
  3. use approved water sources
  4. Boiling, filtering, or chemically treating non-potable water for drinking
30
Q

What are the main characteristics of Rotaviruses?

A
  • a double-layered coat protein with an inner and outer capsid.
  • Their nucleic acid is double-stranded RNA in 11 segments.
31
Q

How are Rotaviruses diagnosed or detected?

A
  1. PCR
  2. EIA
32
Q

What are the sources of contamination for Rotaviruses?

A

transmitted via the fecal-oral route and commonly peak during the cooler winter months.

33
Q

What are the risk groups affected by Rotaviruses?

A

young children

34
Q

What are the diseases associated with Rotaviruses?

A
  • The infectious dose of Rotavirus is less than 100 virus particles, and the incubation period is 1-3 days.

-They cause infantile diarrhea (< 5 years) in developing countries, with dehydration being the main cause of death in young children.

  • Symptoms include:
    1. vomiting and diarrhea,
    2. abdominal pain, and mild fever.
35
Q

How can Rotaviruses be controlled?

A
  1. with a live oral vaccine.
  2. ensuring good personal hygiene practices among food handlers,
  3. thoroughly cooking food to minimum safe internal temperatures,
  4. ensuring shellfish are harvested from approved shellfish-gathering waters,
  5. using approved water sources.
  6. Disinfection with chlorine can inactivate Rotaviruses, although they can survive in water for relatively long periods.
36
Q

What are the main characteristics of molds?

A
  • filamentous fungi that grow in a tangled mass of hyphae.
  • They thrive in humid and warm environments and can grow at low water activity, low temperature, and low pH.
  • viable spores or mycelia
  • can tolerate extreme conditions such as salt, sugar, and acids.
  • produce toxic chemicals called mycotoxins.
37
Q

What is the importance of molds in food?

A
  • Some molds, such as Penicillium, are widely used in food production, like in cheese-making. - However, molds can also produce mycotoxins, which can cause foodborne intoxication and other illnesses.
38
Q

What are the characteristics of Penicillium molds?

A
  • widely distributed and contain many species.
  • They have septate hyphae and form conidiophores with a blue-green, brush-like conidia head.
  • They can also cause fungal rot in fruits and vegetables, spoilage of grains, bread, and meat.
  • Some strains of Penicillium produce mycotoxins such as Ochratoxin A and Rubratoxin B
39
Q

What are the characteristics and sources of Alternaria molds?

A
  • septate fungi that form dark-colored spores on conidia.
  • They can cause rot in tomatoes and contribute to a rancid flavor in dairy products.
  • Some species/strains of Alternaria cause stem-end rot and black rot in citrus fruits.
  • Alternaria can be found in red meats, and certain strains produce mycotoxins.
  • They are capable of growing in a range of temperatures and humidity levels.
40
Q

What are the characteristics and sources of Aspergillus molds?

A
  • widely distributed and contain many species that are important in the food industry.
  • They have septate hyphae
  • produce black-colored asexual spores on conidia.
  • Aspergillus is xerophilic, meaning it can grow in low water activity (Aw) conditions.
  • They can cause spoilage in grains and various foods such as jams, cured ham, nuts, fruits, and vegetables.
  • Some species/strains of Aspergillus, such as Aspergillus flavus, can produce mycotoxins like aflatoxin.
  • Aspergillus molds are able to survive at high temperatures and low Aw.
41
Q

How can Alternaria and Aspergillus molds be detected and diagnosed?

A
  • microscopic examination of the spores and hyphae in contaminated samples.
  • Cultural methods using selective media can also be employed to isolate and identify these molds.
42
Q

What are the sources of contamination for Alternaria and Aspergillus molds?

A
  • Alternaria and Aspergillus molds are present in soil, plants, and the environment.
  • Contamination can occur during the harvesting, processing, and storage of foods.
  • Inadequate hygiene practices and poor storage conditions can also contribute to contamination.
43
Q

What diseases can be caused by consumption of mycotoxins produced by Alternaria and Aspergillus molds?

A
  1. Liver Damage
  2. Cancer
  3. Neurological disorders
44
Q

How can the growth of molds and mycotoxin production be controlled?

A
  1. implementing good agricultural practices, maintaining proper storage conditions, and using fungicides.
  2. Prevention of contamination during processing and storage is crucial to reduce the risk of mold growth and mycotoxin production.
45
Q

What are mycotoxins?

A

Mycotoxins are toxic secondary metabolites produced by strains of molds that can be harmful to humans and animals. They are low molecular weight compounds and can cause food poisoning, blood diseases, nervous system disorders, kidney damage, liver damage, and cancer. Some mycotoxins are mutagenic and carcinogenic.

46
Q

How are mycotoxins diagnosed and detected?

A

Analytical techniques like HPLC, TLC, ELISA, and LC-MS/MS can be used for mycotoxin detection.

47
Q

What are the sources of contamination for mycotoxins?

A
  • Outbreaks due to the consumption of molded food and feed containing toxigenic mycotoxins that were stored long-term have been reported.
  • Contamination can occur during storage, processing, and transport of food.
48
Q

What diseases are associated with mycotoxin exposure?

A

Different mycotoxins can lead to various diseases. For example:
1. aflatoxicosis, caused by aflatoxin (Aspergillus flavus toxin), can cause acute-onset hemorrhage, liver cirrhosis, liver cancer, reproductive issues, and even death.
2. Ochratoxin exposure can lead to kidney damage and liver cancer,
3. Fumonisin exposure can cause pulmonary edema, kidney and liver cancer.
4. Ergot mycotoxins produced by Claviceps purpurea can cause restricted blood flow, gangrene, and hallucinations.

MICR3215: Food Microbiology and Biotechnology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions