Exam #5: Viral GI Tract Infections Flashcards Preview

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Flashcards in Exam #5: Viral GI Tract Infections Deck (40):
1

List the characteristics of the poliovirus.

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

*Stable in acidic pH

2

What allows polio to survive in the stomach?

Fact that it is stable at acidic pH

3

How is polio transmitted?

Fecal-oral

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

4

What are the clinical manifestations of polio?

95% of infections asymptomatic
- Abortive poliomyelitis
- Nonparalytic aseptic meningitis
- Flaccid paralysis

5

What are the symptoms of abortive poliomyelitis?

Sore throat
Fever
Vomiting
Abdominal pain
Constipation

*Does NOT lead to paralysis

6

What are the symptoms of nonparalytic aseptic meningitis?

Nonspecific prodrome
Stiffness

7

What is the incidence of flaccid paralysis?

Less than 1% of infections

8

What are the two different forms of the polio vaccine?

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)

9

How is polio diagnosed?

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

10

What is VAPP?

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

11

What is viral gastroenteritis?

Inflammation of the stomach & intestines caused by a virus

12

What are the symptoms of viral gastroenteritis?

Nausea
Vomiting
Diarrhea

13

How is viral gastroenteritis transmitted?

Fecal-oral

14

What are the four viruses that cause viral gastroenteritis?

Rotavirus
Norovirus
Adenovirus
Astrovirus

*Note that all are non-enveloped

15

How does viral gastroenteritis differ from bacterial gastroenteritis?

- 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

16

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

- Tachycardia
- Hypotension
- Skin tenting
- Sunken eyes
- Tears absent
- Lack of urination

*Possible a sunken fontanelle

17

List the characteristics of the Rotavirus.

DsRNA
Non-enveloped
Segmented

18

Describe the disease burden of Rotavirus.

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

19

What happens to the Rotavirus morphology upon infection?

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

*Note that "Rota" means wheel in Latin

20

Describe the clinical presentation of Rotavirus infection.

- 4-7 days of diarrhea, vomiting, & occasional cough
- Fever greater than 102F is seen in 1/3 of patients

21

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

Young
Malnourished
Immunodeficiency
Bone or liver transplant

22

What time of year is Rotavirus peak?

March

23

What is the most prevalent serotype of Rotavirus?

G1
G2
G9
G3
G4

24

Describe the pathogeneis of Rotavirus infection.

- 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

How is Rotavirus infection diagnosed?

EIA (enzyme-immunoassy) of stool sample

26

How is Rotavirus prevented? How is Rotavirus infection treated?

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

27

What are the forms of the Rotavirus vaccine?

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

What is intussusception?

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

List the characteristics of Norovirus.

Calicivirus family
Non-enveloped
+ssRNA

30

What is the disease burden of Norovirus?

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

31

Describe the pathogenesis of Norovirus.

Same as Rotavirus

32

What does Norovirus show a preference for?

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

What are the four ways that Norovirus can be transmitted?

Generally, fecal-oral:

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

34

List the characteristics of the Adenovirus.

DsDNA
Naked capsid
Fiber protein at vertices

35

Which serotypes of adenovirus cause gastroenteritis?

40 & 41

36

What patient population is most commonly affected by Adenovirus?

Children

37

How is adenovirus infection diagnosed?

Antibody detection in stool sample

38

What is the Sapovirus?

Calicivirideae family
(i.e. similar to Norovirus)

39

List the characteristics of Astrovirus.

Star-shaped
+ssRNA
Non-enveloped

40

Who is most susceptible to Astrovirus infection?

Infants
Young children
Elderly

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