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GI Week 5 > Viral Gastroenteritis > Flashcards

Viral Gastroenteritis Flashcards

1
Q

What is the most common transmission route for viral gastroenteritis?

A

fecal to oral route

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2
Q

True or false: viral gastroenteritis is only human to human transmission

A

false - some are animal to human

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3
Q

What type of diarrhea is caused by viral gastroenteritis?

A

secreotry

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4
Q

True or false: viral gastroenteritis diarrhea contains high levels of leukocytes?

A

false

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5
Q

True or false: viral gastroenteritis diarrhea typically does not contain blood.

A

true

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6
Q

What are the common symptoms of viral gastroenteritis?

A

nausea, vomiting, abdominal pain and diarrhea

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7
Q

What are the two most common viruses causing viral gastroenteritis?

A

rotavirus

norovirus

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8
Q

What are two lesser causes of viral gastroenteritis?

A

adenovirus

astrovirus

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9
Q

Which one has a predilection for the winter: rotavirus or norovirus?

A

rotavirus

norovirus happens all year round

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10
Q

Which one affects children?

A

rotavirus (younger than 5 typically_

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11
Q

What is norovirus particularly associated with?

A

contaminated food and water causes outbreaks in adults

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12
Q

What are the three big bacterial culprits for gastroenteritis?

A

salmonella
clostridium perfringens
camylobater

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13
Q

For rotavirus, RNA or DNA? genome?

A

RNA

DS segmented - class III

SUPER RARE

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14
Q

Describe the capsid for rotavirus.

A

it’s an icosahedral nucleocapsid with a DOUBLE SHELL!

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15
Q

The unique structure of rotavirus’s genome allows it to do what?

A

reassort - like with influenza

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16
Q

True or false: rotavirus affects humans and other vertebrates and often affects multiple species.

A

false - rotaviruses generally can affect both humans and other vertebrates but they exhibit substantial host-range restriction so the straings that affect humans only affect humans

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17
Q

What is the tropism for rotavirus?

A

mature absorptive villous epithelium of the upper two thirds of the small itnestine

18
Q

What layer of the small intestine is rotavirus infection kept to?

A

the intestinal mucosa

19
Q

Describe in general what happens in the cell after the rotavirus virion has entered it?

A
  1. capsid is shed and RNA genome released
  2. viral RNA-dependent RNA polymerase and other enzymes start to transcribe the RNA into mRNA
  3. mRNA is read by host machinery to translate into proteins
  4. virus particles generated
  5. leave the cell by lysis
20
Q

True or false: the released virion particles are immediately infectious and will affect the cells in the same area?

A

false - the outer layer of the capsid needs to mature under lumen conditions before it can be infectious

will typically move down into the distal small bowel before that occurs

21
Q

What characteristic does rotavirus have that is usually reserved for bacterial virulence factors?

A

it has a toxin

22
Q

What is rotavirus’ toxin?

A

NSP4 - it will form a pore in the enterocyte so it lyses

23
Q

How long does it take befor eyou can see cytoplasmic inclusions in the enterocytes where viral replication is taking place?

A

only 8 hours

24
Q

At the height of infection with rotavirus, how many viral particles will be released per gram of stool?

A

10 billion

25
Q

What are some of the reasons why rotavirus has such high death rates in the developing world?

A
  1. treatment is supportive so you need access to hospitals and clean water
  2. malnourishment makes it worse - especially vitamin deficiencies
26
Q

What vitamin will often be given in addition to IV fluids for children with rotavirus in developing countries?

A

vitamin A

27
Q

What are the two vaccines for rotavirus and how do they differ?

A

rotarix - human-infecting rotavirus proteins (attenuated)

rotateq - human and cow rotavirus proteins (even more attenuated)

28
Q

Is norovirus an RNA or DNA virus? genome?

A 
RNA virus
SS+ nonsegmented - class IV (caliciviridae)
29
Q

Describe the norovirus capsid.

A

it’s an icosahedral nucleocapsid

ragged outline (differs from other caliciviruses that have cup-shaped indentations or a star shape)

30
Q

Is norovirus enveloped?

A

no

31
Q

What symptoms will come with norovirus?

A

lower fever than rotavirus (not over 101)
severe vomiting
diarrhea, nausea, abdominal cramps

32
Q

What piece of evidence gets at the massive prevalence of norovirus?

A

75% of people iwll have antibody response to norovirus by age 7

33
Q

How long do symptoms last? How long do you shed the virus?

A

2-3 days

2-3 weeks

34
Q

How many virus particles of norovirus are released per gram of stool?

A

100 billion

35
Q

Why is immunity to norovirus so short lived?

A

the RNA-dependent RNA polymerase makes a lot of mustakes and introduces lots of mutations. DRIFT

this means there are TONS of different strains

36
Q

What strain of norovirus emerged in march of 2012 and is not the dominant strain causing both cruise ship and land-based outbreaks worldwide?

A

GII.4 Syndey

37
Q

What serotypes of adenovirus can cause gastroenteritis?

A

40, 41, 42

38
Q

Is adenovirus a DNA or RNA virus? genome?

A

DNA

DS DNA linear (class I)

39
Q

What is the capsid for adenovirus? Envelope?

A

icosahedral, nonenveloped

40
Q

Do the enteric adenoviruses have a vaccine?

A

no

41
Q

Although it’s not usually done, how can you make a laboratory diagnosis of adenovirus gastroenteritis?

A

you need to do direct analysis of the stool with immunoassays or PCR?DNA probes because the serotypes 40-42 don’t grow in culture

GI Week 5 (6 decks)

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