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Virology > 1 GI tract > Flashcards

1 GI tract Flashcards

1
Q

viruses infecting via the GI tract

A

(Primarily) Non-enteropathogenic viruses

  • Enteroviruses (e.g. polioviruses)
  • Hepatitis A virus
  • Hepatitis E virus
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2
Q

Viruses associated with gastroenteritis

A
  • Rotaviruses (group A)
  • Enteric adenoviruses (type 40/41)
  • Norovirus (NV)
  • Astrovirus
  • Calicivirus
  • Aichi virus – new picornavirus
  • Putative agents (e.g. pestiviruses)
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3
Q

Food or water borne viral disease clinical features

A
  • 1-10 days watery diarrhoea (some viruses are very short, others can last a week or more)
  • vomiting (aerosols contain virus which could contaminate food)
  • abdominal discomfort
  • fever
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4
Q

causes of food/water borne diseases

A

rotavirus
NV
enteric adenovirus
astrovirus

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5
Q

Acute Viral Gastroenteritis: 3 settings

A
  1. Epidemic gastroenteritis
  2. Sporatic gastroenteritis
  3. Sporadic Acute gastroenteritis
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6
Q

Epidemic gastroenteritis

A

semi-closed communities-food/water borne-NV

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7
Q

Sporatic gastroenteritis

A

in very young <2-normally caused by rotavirus but also enteric adenovirus

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8
Q

Sporadic Acute gastroenteritis

A

calicivirus
rotavirus
astrovirus
adenovirus

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9
Q

virus gastroenteritis resistance

A

All look similar with hard capsid shell to protect against outside world – resistant to lots, so can transmit

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10
Q

adenovirus symptoms

A

diarrhoea

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11
Q

adenovirus occurence

A

sporadic

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12
Q

adenovirus immunity

A

longterm

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13
Q

rotavirus symptoms

A

diarrhoea and vomiting

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14
Q

rotavirus occurence

A

sporadic

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15
Q

rotavirus immunity

A

longterm

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16
Q

astrovirus symptoms

A

nonspecific GI

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17
Q

astrovirus occurence

A

sporadic

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18
Q

astrovirus immunity

A

longterm

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19
Q

calicivirus symptoms

A

D+V

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20
Q

calicivirus occurence

A

sporadic

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21
Q

norovirus symptoms

A

D+V

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22
Q

calicivirus immunity

A

longterm

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23
Q

norovirus occurence

A

outbreak

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24
Q

norovirus immunity

A

shortlived

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25
Q

modes of transmission

A

faecel-oral
indirect
direct

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26
Q

faecel-oral transmission

A

ingestion then replication in intestine then excreted is then ingested again

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27
Q

indirect transmission

A
  • from contaminated food/water source (ingested orally by new host, from food or water -food borne)
  • transferred to food/water via ill worker (food-borne)
28
Q

direct transmission

A

person to person
Infected/ill person can infect another person directly
Vomit (aerosol/indirect)
Direct contact (person to person)

29
Q

infectious dose amount

A

normally low 10-100 particles

30
Q

clinically important Gastroenteritis Viruses

A

norovirus
rotavirus
both are transmitted faecally

31
Q

outbreaks of norovirus

A

2013 Oyster outbreak (US), 2007 School sandwiches

32
Q

projectile vomiting

A

another mechanism of transmission
Aerosols spread by projectile vomiting contaminate food and also can transmit virus directly though person to person spread

33
Q

Molluscan Shellfish e.g. oysters

A
  • The foodstuff most commonly linked with NV-associated gastroenteritis
  • Filter-feed
  • Concentrate virus from sewage-contaminated waters
  • Eaten raw or steamed
34
Q

Clinically important Gastroenteritis Viruses

foods associated

A

food-borne viruses

- Fresh fruit, salad items, sandwiches, eggs, frosting on baked goods

35
Q

how is food contaminated

A
  • handling by an ill food worker
  • washing of food using contaminated water
  • items that followed the cooking process
36
Q

rotavirus findings

A
  • Causes severe diarrhoea among infants
  • Transmitted though faecal-oral route through infected hand, utensils possibly through respiratory route
  • Single most important cause of diarrhoeal illness worldwide.
  • Cause severe dehydration
  • Some Vaccines available
37
Q

rotavirus morphology

A
  • a genus within the family reoviridae:
  • 60 spikes extend from the smooth surface of the outer shell (hard capsid shell)
  • Resemble a wheel hence rota
  • Non-enveloped – can propagate in the environment
38
Q

Rotavirus – Genome

A
  • 11 segments of double-stranded RNA
  • structural viral proteins (VP):
    1. outer capsids: VP4 and VP7 (antigens we make vaccines against)
    2. core: VP2, VP6, VP1, VP3
  • nonstructural proteins (NSP): NSP1-5
39
Q

Rotavirus – Classification

A 
group A
group B
group C
group D, E and F
serotypes within these groups
40
Q

group A

A

Significant diarrhoeal illness in the young, most important, vaccines are made to serotypes within this group

41
Q

group B

A

Annual epidemics in adults especially in China

42
Q

group C

A

Sporadic child cases, also in outbreaks

43
Q

group D, E and F

A

In animals thus far

44
Q

Serotypes within rotavirus group A - vaccines

A
  • defined by cross-neutralization with polyclonal antibodies of antigenic specificities (glycoproteins)
  • VP4 antigen: P antigen (protease-cleaved protein)
  • serotype; 8 human rotaviruses
  • VP7 antigen: G antigen (glycoprotein)
45
Q

Rotavirus – Epidemiology

primary trasmission

A

fecal-oral

46
Q

rotavirus transmission

A

ingestion of contaminated food or water and contact with contaminated surfaces

47
Q

rotavirus high rates illness

A

among infants and children below 2 years old, but mild among adults

48
Q

where does Rotavirus effect in body

A

Infects upper two-third of duodenal epithelial cell

49
Q

how does rotavirus effect body

A

Viruses released into lumen and undergo further replication in distal areas –> enterocyte death

50
Q

effects of rotavirus on body

A

Malabsorption

NSP4 toxin = Epithelial permeability ↑

51
Q

rotavirus pathogenesis – malabsorption

A

Reduced absorptive surface, water passes through and end up with diarrhoea
Denudation of microvilli; shortening, flattening and atrophy of villi; invasion of villi by rotavirus causing ischaemia and shortening

52
Q

rotavirus diagnosis

A
  • Antigen Enzyme Immunoassay (EIA) of stool specimens

- RT-PCR (RT – reverse transcription step because it is RNA, to get back to DNA)

53
Q

rotavirus treatment

A
  • Non-specific treatment: oral rehydration therapy to prevent dehydration- problem in the developing world-cause of death
  • Intravenous fluid is required in severe infant cases
  • Immunization by vaccines
54
Q

Rotashield effectiveness

A

Very effective vaccine but was taken off because of the intussusception
5-10X die from rotavirus then the side effect, but was banned

55
Q

noroviruses causes

A 
gasteroenteritis
nausea
vomiting,
diarrhoea
abdominal pain
56
Q

norovirus transmitted by

A

Fecal-oral or person to person, projectile vomiting

57
Q

norovirus source

A

water often from wells
recreational lakes
swimming pools
water stored aboard cruise ships

58
Q

norovirus treatment

A

No vaccine

59
Q

norovirus immunity

A

short lived

60
Q

norovirus culturing

A

non-culturable (can’t grow it in tissue culture cells)

61
Q

norovirus symptoms

A
  • disease is self-limiting
  • characterized by nausea, vomiting, diarrhoea, and abdominal pain
  • Headache and low-grade fever may occur
62
Q

norovirus detection

A

Detected by electron microscopy or Antibody production or PCR

63
Q

norovirus infectious dose

A

unknown but presumed to be low

64
Q

Criteria for suspecting an outbreak due to NV

A 
- Stool cultures
> Negative for bacterial pathogens 
> No viral culture
- Duration of illness
> mean 12-60 hours 
- Vomiting in >50% of cases
65
Q

NVs Epidemiology – incidence

A

NVs (Small Round Structured Viruses) are the most common agent responsible for outbreaks of infectious intestinal disease, responsible for approximately 1/3 of adult outbreaks

66
Q

where do norovirus outbreaks occur

A

places of high population density

67
Q

prevention of norovirus

A
  • Handwashing
  • Proper sanitation
  • Safe drinking water and food

Virology (15 decks)

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