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ID Week 1 > ICL 1.5: Gastrointestinal Viruses > Flashcards

ICL 1.5: Gastrointestinal Viruses Flashcards

1
Q

what must GI viruses overcome to survive and cause an infection?

A
  1. acidic environment of stomach
  2. bile salts of upper small intestine
  3. penetrate mucus coating of gut to bind receptors
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2
Q

what is gastroenteritis?

A

inflammation of the stomach, small and large intestines

GI infections are 2nd major cause of infectious morbidity worldwide

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3
Q

which cell type do GI viruses infect?

A
  1. villus enterocytes = non-dividing, absorptive
  2. crypt cells = dividing, secretory Cl-

enterocytes are on the outside and crypt cells are father in
`

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4
Q

what is malabsorption?

A

loss of enterocytes by direct infection.

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5
Q

what is secondary malabsorption?

A

loss of enterocytes secondary to loss of crypt cells

crypt cells slowly divide and migrate up villus to replace enterocytes

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6
Q

what do gut bacteria do?

A

there’s 500 different species living in your gut

they aid digestion and regulate gut inflammation

they also protect host from pathogenic bacteria

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7
Q

which virus families cause AVG?

A

AVG = acute viral gastroenteritis with diarrhea and vomitting

  1. rotaviruses
  2. enteric adenovirus type 40, 41
  3. caliciviruses (sapoviruses, noroviruses)
  4. astroviruses
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8
Q

what are non-enteropathogenic viruses?

A

viruses that infect the gut but are not pathogenic in the gut

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9
Q

which virus families are non-enteropathogenic viruses?

A
  1. enteroviruses
  2. cosaviruses
  3. reovirus
  4. adenoviruses

viruses that infect the gut but are not pathogenic in the gut

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10
Q

what are opportunistic viruses?

A

viruses that happen in immunosuppressed hosts

ex. HIV infection of gut with diarrhea or weight loss

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11
Q

what is the incubation of AVG?

A

1-3 days

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12
Q

how is AVG spread?

A

fecal-oral spread or possibly respiratory route

fecal-oral route is a route of disease transmission, when the pathogens infecalparticles passing from one host are introduced into theoralcavity of another host

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13
Q

what are the symptoms of AVG?

A
  1. abrupt onset of vomiting (1-3 days)

followed by frequent, copious, watery brown stools (5-8 days)

in severe cases, clear stools (rice water stool)

  1. low grade fever
  2. projectile vomiting
  3. epidemic or sporadic outbreaks
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14
Q

what is a major complication of AVG?

A

dehydration

there’s so much vomitting and diarrhea so people get dehydrated

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15
Q

how do you prevent AVG?

A

hand washing

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16
Q

what are some of the presenting symptoms of rotavirus?

A

rotavirus causes AVG = acute viral gastroenteritis with diarrhea and vomitting

  1. vomiting
  2. watery diarrhea
  3. fever
  4. sudden onset
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17
Q

which population does rotavirus most often effect?

A

little children

older children have milder diarrhea

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18
Q

what is the structure of the rotavirus?

A

naked, segmented dsRNA virus

reoviridae family

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19
Q

what does the rotavirus cause?

A

originates from the hospital!!

it’s a major agent of gastroenteritis and dehydration

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20
Q

what causes diarrhea in rotavirus?

A

viral nsP4 protein

it’s a viral enterotoxin that causes diarrhea

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21
Q

what gives someone immunity to the rotavirus?

A

a specific IgA in the gut lumen

or

IgA and IgG antibodies in the colostrum

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22
Q

what is the most common cause of severe diarrhea in children?

A

rotavirus

it’s the most common cause of severe diarrhea among children, with hospitalization of ~55,000 children/year in USA and the death of 600,000 children annually worldwide

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23
Q

what is the incubation period of the rotavirus?

A

about 2 days

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24
Q

what is the progression of the rotavirus?

A

incubation for 2 days

then vomiting and watery diarrhea for 3 - 8 days

fever and abdominal pain occur frequently too

immunity after infection is incomplete, but repeat infections tend to be less severe than the original infection

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25
Q

during what time of the year does rotavirus peak?

A

winter months

and in kids

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26
Q

how many strains of the rotavirus are there?

A

7: A-G

A-C are human viruses

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27
Q

what is rotavirus A?

A

human virus

effects infants less than 24 months of age

older children have milder diarrhea

in undernourished children-diarrhea and dehydration
can cause death

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28
Q

what is type B rotavirus?

A

viruses infect humans and swine

associated with outbreaks of diarrhea in older children, adults in China

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29
Q

what is type C rotavirus?

A

disease in adults/children in Asia

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30
Q

how do you diagnose rotavirus?

A
  1. EM

fecal supernatants are incubated with virus-specific antibodies

their ability to cause clumping of virus particles identifies the presence of specific antigens (proteins) and thereby identifies the virus

  1. RT-PCR
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31
Q

how do you treat rotavirus?

A
  1. RotaTeq vaccine = live, oral, pentavalent
  2. Rotarix vaccine = human, live attenuated, rotavirus
    strain of G1P[8] specificity

Rotarix and RotaTeq trials in Africa and Asia found that the vaccines dramatically reduced severe disease among infants in developing countries, where a majority of rotavirus-related deaths occur

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32
Q

Rotavirus Flashcard: what is the virus family, pathogenesis, clinical symptoms, diagnosis and treatment/prevention of rotavirus?

A

Virus: Reoviridae, segmented dsRNA genome, naked virion

Pathogenesis: Fecal-oral infection, also infects respiratory route, viral nsP4 is a viral enterotoxin, affects children

Clinical: Most common cause of severe diarrhea in children, incubation ~2 days, seven antigenic types (A-G) – (A-C) are human viruses

Diagnosis: Immuno-EM and RT-PCR

Treatment and Prevention: Rotateq and Rotarix vaccines

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33
Q

what is the structure of the adenovirus?

A

naked, linear dsDNA virus

34
Q

what is the pathogenesis and clinical features of the adenovirus?

A

AVG in infants

involution of part of the intestine is a complication

virus infects Peyer’s patches

35
Q

how do you treat adenovirus?

A

antibodies are essential for recovery but there’s no treatment or prevention….

36
Q

how do you diagnose adenovirus?

A

ELISA assays to detect viral antigens or antibodies

37
Q

Adenovirus 40 & 41 Flashcard: what is the virus family, pathogenesis, clinical symptoms, diagnosis and treatment/prevention of adenovirus?

A

Virus: dsDNA genome, naked virion

Pathogenesis and clinical: AVG in infants, infects Peyer’s patches

Diagnosis: ELISA

Treatment and Prevention: None

38
Q

rotavirus vingette

A

A 9-month-old baby girl was brought to the emergency department of a local general hospital during the winter with a 2-day history of vomiting, watery diarrhea and fever.

The patient had been well until 24 hours before her presentation, when she had experienced the acute onset of vomiting followed by multiple episodes of diarrhea. She refused to eat, and she drank very little fluid. Her parents were concerned about dehydration. The family had not traveled outside the US recently, but the mother related that she had been leaving her baby in a day care center for 3 days a week for the past 3 months.

39
Q

which viruses are part of the caliciviridae family?

A
  1. norovirus
  2. sapovirus
  3. lagovirus
  4. vesivirus
  5. sapporovirus
  6. norwalk virus
40
Q

norovirus case study

A

Within 48 hours of a college football game in Philadelphia, 158 students with symptoms of gastrointestinal disease visited the university health service. The predominant symptoms included nausea in 99%, vomiting in 75%, diarrhea in 48%, and headache, fever and myalgias. Marching band members, football players. And faculty and staff from both universities had similar symptoms. A total of several hundred individuals were afflicted with similar symptoms.

41
Q

what is the structure of the caliciviridae family?

A

small, (+) RNA naked virus

42
Q

how are caliciviruses transmitted?

A
  1. fecal-oral route like via contaminated food/water

2. aerosol

43
Q

which caliciviruses are associated with gastroenteritis?

A

sapoviruses and noroviruses are etiologic agents of human gastroenteritis

44
Q

who does the Norwalk virus effect?

A

it’s in the Caliciviridae family

it effects older children and adults

it’s known as the cruise ship virus

45
Q

what is the pathogenesis of the calicivirus? symptoms?

A

it infects the intestinal brush border and prevents proper absorption of water and nutrients

this causes diarhea, vomiting, abdominal cramps, nausea, headache, malaise and fever

no seasonal incidence

46
Q

how do you diagnose calicivirus?

A

ELISA assays to detect viral antigens or antibodies

47
Q

how do you treat caliciviruses?

A

no vaccines or antivirals…

48
Q

Calicivirus Flashcard: what is the virus family, pathogenesis, clinical symptoms, diagnosis and treatment/prevention of calicivirus?

A

Virus: Caliciviridae, small, (+) RNA, naked (cup-like projections)

Pathogenesis: Fecal-oral and aerosol transmission, AVG pathogen

Clinical: Infects intestinal brush border cells, Diarrhea, vomiting, abdominal cramps, nausea, headache, malaise and fever

Diagnosis: ELISA

Treatment and Prevention: No vaccine

49
Q

what’s the structure of astroviruses?

A

small, (+) strand naked virions

50
Q

what are the clinical features of astroviruses?

A

outbreaks of diarrhea in children

peaks in winter in US

51
Q

how do you diagnose astroviruses?

A

ELISA assays to detect viral antigen or antibodies in patient specimens

52
Q

what is the structure of picornaviridae?

A

small, naked (+) strand RNA virions

53
Q

what are the three classes of picornaviridae?

A
  1. Hepatitis A
  2. Rhinovirus
  3. Enterovirus

enteroviruses = acid stable and stable at 37 C

  • polioviruses
  • coxsackie A and B
  • ECHO virus
  • vosaviruses

non-GI tract effecting viruses = stable at 33 C but not in acid

  • rhinovirus
  • heparnavirus
54
Q

Which viruses are enteroviruses? in what environments are enteroviruses stable?

A
  1. Polio viruses
  2. Echovirus
  3. Coxsackie A and B

37 C

acid stable = survive in stomach acid

55
Q

what is the clinical presentation of enteroviruses?

A

broad disease spectrum = wide range of clinical outcomes

but usually this is the most unapparent infection with no symtpoms…

Enteroviruses are the #1 cause of severe aseptic meningitis = meningitis caused from non-bacterial organism = glucose levels are normal but protein levels are elevated —> kids are really susceptible

Can also cause myocarditis

56
Q

how do you diagnose picornaviridae?

A

typed by neutralization of infectivity with specific Abs

virus isolation; detect a specific rise in antibody levels (acute/convalescent titers); IgM capture ELISA; by RNA sequences (RT-PCR) of virus genome/mRNA recovered from patient samples

57
Q

how is picornavirus spread?

A

fecal-oral spread/secretions

the virus sheds in feces for weeks…

the feces end up in food or water or the hands of kids and ends up in the mouth

this is why picornaviruses need to be acid stable! So Hepatitis A, polio, echovirus, and coxackie A&B are all acid stable

**only the rhinovirus is transmitted through the respiratory route

58
Q

how can you prevent picornavirus?

A

hand washing inhibits transmission cycle!

it’s usually spread via fecal-oral route

59
Q

what time of the year is picovirus most common?

A

several serotypes circulate each year

but there’s a summer/fall peak

Think of the peak animal nursery; people would only go during the summer and fall

60
Q

which cells does polio infect?

A

virus infects lymphoid cells in pharynx (tonsils) to intestines (Peyer’s patches) to feces

Peyer’s patches are where the virus replicates and it takes 2-3 weeks

in some patients, the infection goes from GI to a primary viremia = virus in the blood –> the virus then spreads to the liver, heart, spleen resulting in increased amounts of virus reintroduced into the blood = secondary viremia

the higher levels of virus contribute to the virus crossing the blood-brain barrier and infecting neurons in the CNS = paralysis

61
Q

what are the clinical features of polio?

A

90% of infections are asymptomatic (2-3 days)

  1. aseptic meningitis
  2. asymmetric flaccid paralysis; usually concentrated in the legs
  3. brain stem infected = Bulbar polio
  4. paralytic poliomyelitis in 1% of infections
  5. myalgia
  6. respiratory insufficiency if the paralysis effects the lungs= biggest cause of death in polio patients
62
Q

what is Bulbar polio?

A

brain stem is infected

paralysis of cranial nerves, muscles of respiration

63
Q

how do we prevent polio?

A
  1. a trivalent vaccine against 3 serotypes

immunity to each serotype is needed for full protection

  1. Pediarix

There is no treatment!!

64
Q

what kind of vaccine is the polio vaccine?

A

2 versions

  1. a live attenuated vaccine = Saban vaccine

Given orally; it mimics natural course and route of infection, leads to mucosal IgA immunity

  1. killed vaccine = Salk vaccine

Given IM, only leads to IgG immunity

*We use the killed vaccine in the US

65
Q

what are the advantages and disadvantages of the live attenuated polio vaccine?

A

PROS
1. attenuated and can increase antigen dose

  1. there is limit to virus production (mutations reduce replication, virion stability)
  2. oral live form makes both IgG and IgA antibodies!
  3. since this contributes to herd immunity (unintended infection of others), it benefits at the community/regional level

CONS
1. live vaccine can be shed in the feces and possibly revert to a form that can cause paralysis in another person

66
Q

how is the killed polio vaccine administered and what does it do?

A

Aka Sulk vaccine

it is administered intramuscular (IM)

Since it bypasses GI tract since its an injection it only forms IgG antibodies and no IgA antibodies which is the primary antibody in mucosal surfaces

antigen dose is fixed = no replication

current recommendation is 3-4 doses

67
Q

what is Pediarix?

A

used to treat polio

it’s a combination product containing DTaP, hepatitis B, and inactivated polio vaccines

it’s licensed for children 6 weeks through 6 years of age

68
Q

what is VAPP?

A

VAPP = vaccine-associated paralytic polio

VAPP is clinically indistinguishable from paralytic poliomyelitis caused by wild-type polioviruses and occurs within 60 days of OPV exposure

69
Q

Poliovirus Flashcard: what is the virus family, pathogenesis, clinical symptoms, diagnosis and treatment/prevention of poliovirus?

A

Virus: Picornaviridae, enterovirus genus, + ss RNA
genome, naked virion

Pathogenesis: infects lymphoid cells in pharynx -to intestines – to feces, primary and secondary viremia, can cross blood-brain barrier

Clinical: paralytic poliomyelitis, aseptic meningitis, asymmetric flaccid paralysis

Diagnosis: not done

Treatment and Prevention: vaccine trivalent (3 serotypes), live attenuated (Sabin) and heat killed (Salk)

70
Q

what are cosaviruses?

A

second most common human enteric infections

new genus of enteroviruses

71
Q

what is the structure of coxsackieviruses?

A

(+) RNA, naked virions

72
Q

what are coxsackieviruses?

A

Coxsackie A: 23 serotypes

  • herpangina (vesicular pharyngitis)
  • hand, foot and mouth disease (vesicles) *type A16
  • congenital heart disease newborns
  • aseptic meningitis

Coxsackie B: 6 serotypes

  • pleurodynia (epidemic myalgia)
  • acute infectious myocarditis (50% mortality in infants)
  • acute pericarditis
73
Q

what are ECHO viruses?

A

enteric, cytopathogenic, human orphan - 32 serotypes

can be isolated from “normal” patients

ECHO viruses cause diseases similar to Coxsackie but its infections tend to be less severe than Coxsackie infections

74
Q

what are enteroviruses 68-71?

A

EV #70: acute hemorrhagic conjunctivitis (associated also with some infections by Coxsackie A24)

EV #71: is associated with hand, foot and mouth disease (outbreak of vesicles in these locations) in children

75
Q

which virus families are nonenteropathogenic?

A

enteroviruses

reovirus

some adenoviruses

76
Q

which virus families cause diarrhea and vomiting?

A

rotaviruses

enteric adenovirus types 40 and 41

caliciviruses (sapoviruses, noroviruses)

astroviruses

77
Q

Which virus is the primary cause of the common cold?

A

Rhinovirus

78
Q

How is the rhinovirus transmitted?

A

Even though it’s a picovirus, it is NOT transmitted through the fecal-oral route

It’s an upper respiratory infection which makes sense because it causes the common cold

79
Q

What is the structure of the polio virus? What family does it belong to?

A

Part of the Picornavirus family —> enterovirus subtype

(+) sense, naked ssRNA virus

80
Q

How is poliovirus transmitted?

A

It’s a picovirus so it’s transmitted via the fecal-oral route

In order for the virus to do so, it needs to be able to handle the acidic conditions in the stomach —> polio is an acid stable virus!

ID Week 1 (15 decks)

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