Microbiology - Enteric viruses I & II - Rebecca Greenblatt Flashcards Preview

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Flashcards in Microbiology - Enteric viruses I & II - Rebecca Greenblatt Deck (42):
1

Reoviruses have a segmented genome, which has what mode of gaining genetic diversity?

Reassortment

2

Transmission: Rotavirus (reovirus)

fecal-oral

3

Orthoreoviruses cause:

Mild GI symptoms

4

Rotavirus causes severe:

dehydration, even though diarrhea is self-limited

5

What cells does rotavirus act on?

The cells of the small intestinal villi

6

What does rotavirus have that acts like an enterotoxin?

NSP4 - rotavirus nonstructural protein 4 - interferes with sodium transport pumps - profuse watery diarrhea

7

Phylogeny: Rotavirus

ds RNA virus
+ sense
icosahedral
naked

8

Phylogeny: Norovirus

ss RNA virus
- sense
icosahedral
naked

9

Transmission: Norwalk virus (norovirus)

fecal-oral

10

IU: Norwalk virus

low

11

IU: Rotavirus

high

12

Pathogenesis: Norovirus

Infection damages microvilli in small intestine → malabsorption

13

Vomiting is more common in what enterovirus?

Norovirus - slows gastric emptying as comparing with rotavirus

14

What is primary viremia?

Successful virus travels in blood to seed replication site(s). LOW LEVELS in blood.

15

What is secondary viremia?

New virus travels from replication site(s) to shedding site(s). HIGHER LEVELS in blood.

16

Phylogeny: Picornaviruses ie Poliovirus, Hep A, Coxsackievirus

Small
naked
icosahedral
+ sense
ss RNA

17

Coxsackie A causes:

herpangina, hand-foot-and-mouth disease, acute hemorrhagic conjunctivitis

18

Coxsackie B causes:

myocarditis
pleurodynia
meningitis

19

Site of replication: Enteroviruses and Picornaviruses

All replicate in gut

20

T/F: Poliovirus is human-restricted.

True

21

How does poliovirus enter/infect epithelial/lymphoid cells in the gut lining?

CD155 receptor - found in gut AND cns gray matter cells

then spreads to the blood stream and regional lymph nodes

22

How does nerve death occur in poliovirus?

Nerve death results both from lytic virus replication and overenthusiastic
immune response

23

Viruses that produce polyproteins are vulnerable to what class of drugs?

Protease inhibitors

24

Where is the location of acute poliomyelitis infection?

Infection of the anterior horn motor neurons of the spinal cord (muscle symptoms) and brain stem (respiratory symptoms)

Flaccid asymmetric weakness and muscle atrophy due to loss of motor neurons and denervation of their associated skeletal muscles

Of acute poliovirus infections, 1-2% result in neurologic symptoms.

25

Transmission: Poliovirus

Fecal-oral

26

Risk factors: paralytic poliomyelitis

young age, advanced age, recent hard exercise, tonsillectomy, pregnancy, immunosuppression

27

________ can cause herpangina & has
been associated with severe complications. Fatalities, mostly in infants aged 6-11 months, have been reported.

Enterovirus 71

28

Most common cause of herpangina:

Coxsackie A
Enterovirus - picornavirus

29

Symptoms of herpangina:

Acute febrile illness

Small vesicular or ulcerative lesions on the posterior oropharyngeal structures

Typically occurs during the summer

Frequently in children, also young adults

Coxsackie A

30

What viruses are primarily resonsible for acute hemorrhagic conjunctivitis?

Coxsackie group A24 (CA24) and enterovirus E70 (EV70)

31

Why should the use of topical steroids be avoided in the treatment of acute hemorrhagic conjunctivitis?

Treatment with topical steroids should be avoided : risk of microbial superinfection of the cornea

32

Viral myocarditis is most commonly caused by:

Adenovirus;
Enterovirus

Coxsackie B - one of the more severe presentations

33

T/F: In viral myocarditis, CK-MB and Troponin I may be elevated.

True

34

What is pleurodynia?

Pleurodynia (ploor-uh-din-ee-uh) (“Devil’s Grip”) is an uncommon complication of infection by coxsackievirus B or a few others

Sudden occurrence of lancinating chest pain attacks
Fever
Malaise
Headache

35

What is the anatomic structure targeted by pleurodynia?

The striated muscle is the actual anatomic structure targeted by the coxsackievirus B and is responsible for the attacks of severe chest pain.

36

Transmission: Coxackie B

Fecal-oral

37

What physical exam finding points in the direction of pleurodynia/Coxsackie B infection?

Pleural/friction rub on lung exam

38

When is pleurodynia life-threatening?

Infants

39

In the developed world, >85% of aseptic/viral meningitis is caused by:

Enteroviruses

40

Very young children with aseptic meningitis can present with what unique symptoms?

Fever w/ cold hands and feet;
Fretful, dislike of being handled,
pale, blotchy skin;
blank staring/unresponsive

41

Enteroviruses and HSV can cause _______ in infants

septic shock

42

Ospithotonic positioning may be a sign of _______ or may be seen in an infant who is attempting to compensate for airway edema or stridor.

meningitis