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Microbiology > Exam #5: Viral GI Tract Infections > Flashcards

Exam #5: Viral GI Tract Infections Flashcards

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Biology 101 flashcards
1
Q

List the characteristics of the poliovirus.

A

Pirconaviridiae family
+ssRNA
Three serotypes (P1, P2, & P3)

*Stable in acidic pH

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2
Q

What allows polio to survive in the stomach?

A

Fact that it is stable at acidic pH

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3
Q

How is polio transmitted?

A

Fecal-oral

Note that the virus is shed in the stool for weeks following infection

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4
Q

What are the clinical manifestations of polio?

A

95% of infections asymptomatic

  • Abortive poliomyelitis
  • Nonparalytic aseptic meningitis
  • Flaccid paralysis
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5
Q

What are the symptoms of abortive poliomyelitis?

A 
Sore throat
Fever
Vomiting 
Abdominal pain
Constipation

*Does NOT lead to paralysis

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6
Q

What are the symptoms of nonparalytic aseptic meningitis?

A

Nonspecific prodrome

Stiffness

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7
Q

What is the incidence of flaccid paralysis?

A

Less than 1% of infections

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8
Q

What are the two different forms of the polio vaccine?

A

Salk= inactivated polio vaccine (via exposure to formaldehyde)

Sabin= Oral, live, attenuated

*Note that this can be shed in the stool for up to six week following vaccination (and passed to other)

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9
Q

How is polio diagnosed?

A

Isolate virus from stool & sequence to differentiate between wild-type and vaccine

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10
Q

What is VAPP?

A

Vaccine Associated Paralytic Poliomyelitis

1/2 million doses of Sabin reverted to a neurotropic strain that caused CNS symptoms–>lead to paralytic polio symptoms & use was discontinued

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11
Q

What is viral gastroenteritis?

A

Inflammation of the stomach & intestines caused by a virus

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12
Q

What are the symptoms of viral gastroenteritis?

A

Nausea
Vomiting
Diarrhea

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13
Q

How is viral gastroenteritis transmitted?

A

Fecal-oral

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14
Q

What are the four viruses that cause viral gastroenteritis?

A

Rotavirus
Norovirus
Adenovirus
Astrovirus

*Note that all are non-enveloped

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15
Q

How does viral gastroenteritis differ from bacterial gastroenteritis?

A
  • Incubation period for viral will NEVER be “hours” because replication must occur vs. bacterial gastroenteritis that can onset in hours (or min) because of preformed toxin
  • Vomiting is more prominent in viral
  • Diarrhea is non-bloody in viral gastroenteritis
  • Viral is a “diagnosis of exclusion” aside from rotavirus & astrovirus
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16
Q

A common effect of viral gastroenteritis is dehydration. What are the symptoms of severe dehydration?

A
  • Tachycardia
  • Hypotension
  • Skin tenting
  • Sunken eyes
  • Tears absent
  • Lack of urination

*Possible a sunken fontanelle

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17
Q

List the characteristics of the Rotavirus.

A

DsRNA
Non-enveloped
Segmented

18
Q

Describe the disease burden of Rotavirus.

A
  • Responsible for 5-10% of all gastroenteritis among children less than 5 years-old
  • Highest incidence among children 3 - 35 months of age
19
Q

What happens to the Rotavirus morphology upon infection?

A

Rotavirus looks like a wheel due to the spoke-like appearance of its virion particles

*Note that “Rota” means wheel in Latin

20
Q

Describe the clinical presentation of Rotavirus infection.

A
  • 4-7 days of diarrhea, vomiting, & occasional cough

- Fever greater than 102F is seen in 1/3 of patients

21
Q

What patient populations are at risk for life-threatening complications of Rotavirus infection?

A

Young
Malnourished
Immunodeficiency
Bone or liver transplant

22
Q

What time of year is Rotavirus peak?

A

March

23
Q

What is the most prevalent serotype of Rotavirus?

A 
G1 
G2
G9
G3 
G4
24
Q

Describe the pathogeneis of Rotavirus infection.

A
  • Ingested virus infects the tip of the intestinal villi
  • Infected cells are damaged & lost
  • This villi blunting leads to malabsorptive diarrhea

*Regeneration of the villi within 4-7 days= end of symptoms

25
Q

How is Rotavirus infection diagnosed?

A

EIA (enzyme-immunoassy) of stool sample

26
Q

How is Rotavirus prevented? How is Rotavirus infection treated?

A
  • Prevention of fecal-oral transmission
  • IgA colostrums (first breast milk produced by the nursing other)
  • Vaccine
27
Q

What are the forms of the Rotavirus vaccine?

A

BOTH are live attenuated, oral vaccines

1) Rotateq
- Protective against G1 i.e. the reassortment of strains G4 & G9 (bovine & human reassortment)
2) Rotatrix

*Recommendation is vaccination prior to 12 weeks of age in all children & DOES NOT increase the risk of intussusception

28
Q

What is intussusception?

A

Medical condition in which a part of the intestine invaginates (folds into) into another section of intestine, similar to the way the parts of a collapsible telescope slide into one another

29
Q

List the characteristics of Norovirus.

A

Calicivirus family
Non-enveloped
+ssRNA

30
Q

What is the disease burden of Norovirus?

A

Causes 96% of all outbreaks of nonbacterial gastroenteritis in the US (in all patient populations/ age groups)

31
Q

Describe the pathogenesis of Norovirus.

A

Same as Rotavirus

32
Q

What does Norovirus show a preference for?

A

Individuals expressing specific histo blood-group antigens; specifically, B antigen

*Note that this is only for one specific type of Norovirus (others infect other antigen groups)

33
Q

What are the four ways that Norovirus can be transmitted?

A

Generally, fecal-oral:

1) Person to person
2) Fomites
3) Waterborne
4) Contaminated Food

34
Q

List the characteristics of the Adenovirus.

A

DsDNA
Naked capsid
Fiber protein at vertices

35
Q

Which serotypes of adenovirus cause gastroenteritis?

A

40 & 41

36
Q

What patient population is most commonly affected by Adenovirus?

A

Children

37
Q

How is adenovirus infection diagnosed?

A

Antibody detection in stool sample

38
Q

What is the Sapovirus?

A

Calicivirideae family

i.e. similar to Norovirus

39
Q

List the characteristics of Astrovirus.

A

Star-shaped
+ssRNA
Non-enveloped

40
Q

Who is most susceptible to Astrovirus infection?

A

Infants
Young children
Elderly

Microbiology (49 decks)

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