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RUSVM Epi Summer 17 > Foodborne Dz: Viral > Flashcards

Foodborne Dz: Viral Flashcards

1
Q

T/F: Viruses are the most common cause of foodborne illness

A

TRUE

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2
Q

T/F: Testing for viral etiologies of diarrheal dz is routinely done

A

FALSE

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3
Q

Hepatitis __ virus accounts for about 90% of viral hepatitis infections worldwide

A

A

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4
Q

T/F: Majority of Hepatitis A infections are asymptomatic

A

TRUE

**infection in infancy or childhood is asymptomatic

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5
Q

Where does hepatitis A replicate? How is it shed?

A

replicates in the liver and causes hepatitis

then the virus is shed into bile and is excreted in the feces

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6
Q

Many cases of hepatitis A are acquired when _______

A

Traveling

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7
Q

Who is the most important reservoir of Hepatitis A?

A

Humans

via feces

The virus is shed 1-3 weeks before illness and up to several weeks after recovery ***long shedding period

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8
Q

T/F: In areas with high endemicity of Hepatitis A there are numerous clinical cases reported

A

FALSE

  • in these areas the majority of the population are infected as children - therefore there is minimal clinical dz
  • occurs in least developed countries with poor socioeconomic status
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9
Q

In more developed countries where there is a low endemicity of Hepatitis A, is there a high or low clinical disease?

A

There are more outbreaks of clinical disease

In these countries, the average age of infection goes up. More adults are susceptible

*remember in children/young people - they tend to be asymptomatic

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10
Q

What are the modes of transmission of Hepatitis A and which is most important?

A

Direct: Fecal-oral = most important (close personal contact, poor personal hygiene, infected food handlers)

Vehicle: food, water contaminated with feces (improper sewage tx)

*associated foods = shellfish from contaminated waters, raw produce, Contaminated drinking water, Uncooked foods and cooked foods that are not reheated after contact with an infected handler

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11
Q

What is the incubation period of hepatitis A?

A

average is 28 days

Can range from 15-50 days

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12
Q

What is the duration of illness associated with Hepatitis A?

A

varies from 2 weeks to 3 months

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13
Q

What clinical signs will be associated with a Hepatitis A infection?

A

fatigue, dark urine, jaundice, flu-like symptoms

Nausea/vomiting, anorexia, fever, malaise, or abdominal pain

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14
Q

What is described as a positive case definition of hepatitis A according to the CDC?

A
  1. discrete onset of clinical signs: nausea, anorexia, fever, malaise, or abd pain
  2. Jaundice or elevated serum aminotransferase

AND

Either positive serologicatl test for IgM to Hep A
OR
An epidemiological link to a lab confirmed case (within the household/sexual partner)

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15
Q

How can Hep A be prevented?

A
  1. Target the host: Vaccination (this will reduce the reservoir)
  2. Target the vehicle: proper sewage/water tx, proper preparation, cooking, and handling of food - wash veggies and fruit, ***good sanitation
  3. Block transmission: personal hygiene and hand washing
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16
Q

What is the group of related single stranded RNA, non-enveloped viruses, that cause acute gastroenteritis in humans, and are also known as “winter vomiting disease”?

A

Noroviruses

(family- calicivirues)

6 recognized groups

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17
Q

What is the most common cause of foorborne illness around the world?

A

noroviruses

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18
Q

Noroviruses account for ____% of all KNOWN foorborne illnesses in the US

A

58%

only 20% of all domestically acquired foodborne illness

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19
Q

Who is the reservoir of Noroviruses?

How is it shed?

A

PEOPLE

Feces** and vomit
Shedding begins 18 hours post infection - usually lasts for about 28 days (ranges from 13-56d)

**95 billion viral particles per gram of feces

20
Q

T/F: Once infected with a norovirus, you will gain immunity and likely not be infected again

A

FALSE

*there are multiple strains with little cross protection

21
Q

What are the modes of transmission of noroviruses?

A
  1. Direct: fecal oral route (close personal contact, poor personal hygiene)
  2. Vehicle:
    a- food/water contamination with feces (Infected food handlers = MOST IMPORTANT) Also improper sewage tx
    –> associated foods: shellfish harvest from contaminated waters, raw produce, uncooked or cooked foods that are not reheated after contact with infected handler

b- FOMITES: surfaces contaminated with fecal material (virus can survive at least one week on counters/surfaces)

22
Q

What is the incubation period and duration of illness of noroviruses?

A

Incubation= 12 to 48 hours

Duration of illness = 24 - 72 hours

23
Q

What clinical signs are associated with noroviruses?

A

Nausea, acute onset of vomiting, watery non-bloody dhr with abdominal cramping

24
Q

What are the Kaplan Criteria used to determine if an outbreak was caused by a norovirus? (there are four requirements)

A
  1. Mean (median) illness duration = 12-60 hours
  2. Mean (median) incubation period = 24-48 hours
  3. More than 50% of people affected –> vomiting
  4. No bacterial agent found

(other diagnosis done by Real time PCR of stool/vomit/environmental samples)

25
Q

Who is norovirus treatment most important for?

A

Children

Supportive care: fluids/electrolytes

26
Q

How can norovirus be prevented?

A
  1. Target vehicle: proper preparation, cooking, handling of food (MOST IMPORTANT), good sanitation
  2. Block transmission: personal hygiene, and hand washing
27
Q

T/F: Outbreaks of norovirus are often smaller scale

A

FALSE

Often larger due to: multiple potential modes of transmission, prolonged asymptomatic shedding, virus stability in environment, lack of cross protective immunity

28
Q

The increase in gastroenteritis on cruise ships is primarily attributed to ______

A

Noroviruses

29
Q

What shellfish has norovirus been known to be transmitted through?

A

Raw oysters

30
Q

T/F: Strains of rotavirus in animals and people are distinct

A

TRUE

31
Q

The most common cause of severe diarrhea in children around the world is ______

A

Rotavirus

most (95%) of children infected by 5 years of age in the US

32
Q

When do seasonal outbreaks of rotavirus tend to occur?

A

In the winter

November to April

33
Q

Who is the reservoir for rotavirus? How is it shed?

A

People are the reservoir

shed through feces 2-10 days after onset of dhr

34
Q

T/F: Subsequent infections with rotavirus have mild or no diarrhea

A

True

First infection provides partial immunity

35
Q

What is the mode of transmission of rotavirus?

A
  1. Direct: fecal-oral route (close contact with infected person/poor personal hygiene)
  2. Vehicle - food/water contaminated with feces (contaminated by infected food handlers - salad, fruit)
    FOMITES: contaminated with feces - virus lasts for weeks in the environment
36
Q

Where are rotavirus transmission risks the highest for children?

A

Day care centers
Hospitals
Parents who work in day cares or hospitals

*immunodeficient people also have high infection risk

37
Q

What is the incubation period of rotatvirus? How long is the typical duration of illness?

A

Incubation is less than 48 hours

Duration of illness = 3-7 days

38
Q

What clinical signs are associated with rotavirus infection?

A

Diarrhea - in most cases is self limiting
May see temporary lactose intolerance
Dehydration, electrolyte imbalances

*infections in children 3-36 months are most severe

39
Q

What are the definitive case definitions for rotavirus infection?

A

None: just acute dhr in children under 36 months that are not vaccinated - outbreaks are usually in the winter

and

Rotavirus antigen in stool detected with enzyme immunoassay

40
Q

How are rotavirus outbreaks prevented?

A
  1. target the host = vaccination
  2. Target the vehicle: Proper preparation, cooking, and handling of food. Good sanitation
  3. Block transmission: personal hygiene, hand washing, diapers etc
41
Q

What is the rotavirus vaccination strategy?

A

Vaccinate at a very young age to delay age of infection

42
Q

What are other viral agents that can cause GI signs in humans and are transmitted via contaminated food?

A

Astroviruses
Adenoviruses
Parvoviruses

  • usually self limiting infections
  • prevention via targeting vehicle (food prep sanitation) and blocking transmission (hand washing)
43
Q

T/F: Foodborne viral illnesses typically have longer incubation periods than bacterial pathogens

A

FALSE

Typically shorter **Hep A is the exception

44
Q

T/F: Foodborne viral illnesses tend to cause more vomiting and less diarrhea than bacterial foodborne illnesses

A

TRUE

virus = vomit

45
Q

Which foodborne illnesses tend to have a longer duration of symptoms, viral or bacterial?

A

Bacterial have longer duration

RUSVM Epi Summer 17 (29 decks)

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