Micro Viral Gastroenteritis

Front 1

Sx of gastroenteritis ("stomach flu")?

Back 1

diarrhea (watery), fever, abdominal pain, vomiting

Front 2

impact of diarrheal illness in the U.S. per year?

Back 2

diarrhea: 35 million cases (rotavirus-3.5 mil)
hospitalizations: >200K (50K)
deaths: ~500 (~25)

Front 3

most common causes of diarrhea in the U.S.?

Back 3

rota virus then norwalk virus

Front 4

global impact of rotavirus?

Back 4

~800.000 deaths/ yr caused by rotavirus diarrhea

mostly in India, africa some Asia and S. Am

Front 5

genome and significance of the following major causes of viral gastroenteritis:
Rotavirus A (reo)
Rotavirus B,C (atypical; reo)
Noro (Calici)
Astro
enteric Adeno (type 40,41

Back 5

Rota A: ds, segmented RNA; major cause diarrhea in kids
Rota B/C: rare in U.S
Noro: ssRNA+, major cause epidemics in adults
astro: ssRNA+; kids and elderly
adeno: dsDNA, linear: 2nd to rota for diarrh in kids

Front 6

family and genus of rotavirus?

Back 6

family: reoviridae
genus: rotavirus

Front 7

rotavirus structure?

Back 7

non-enveloped, double capsid
genome of 11 dsRNA segments
core has gene segments, vRNAdRP and capping enzymes
very stable particle

Front 8

rotavirus replication?

Back 8

1. attach and penetrate
2. tsc in core
3. trans
4. immature progeny particle
5. replication in particle
6. assembly
7. release by lysis

Front 9

epidemiology of rotavirus?

Back 9

1. worldwide
2. children infected early
3. tran fecal-oral, fomites
4. max virus shedding 2-5 d after diarrhea stars (or w/o sx)
5. outbreaks in preschools, daycare, hosp
6. more common fall, winter, spring

Front 10

rotavirus is the main cause of diarrhea in what age group?

Back 10

infants 6-14 months old

Front 11

how are rotavirus groups A-G determined?

Back 11

by VP6 capsid protein

**most human rotavirus infection by group A serotype

Front 12

how are serotypes w/in groups determined for rotavirus?

Back 12

based on neutralizing Ab's to outer capsid proteins VP7 and VP4

VP7 G1-G14
VP4 P1-P8

Front 13

rotavirus pathogenesis

Back 13

1. ingested, infects tip of villi in SI and spreads
2. release of virus into lumen
3. infected cells damaged/lost
immature cells w/ decr absorption capacity
4. fluid accum in lumen: diarrhea and dehydration
5. virus rep ceases
6. crypt cells repop villi

Front 14

rotavirus immunity

Back 14

1. short lived mucosal (IgA) and
"incomplete" systemic immunity

2. reinfection, but less severe sx (1st infection worst)

*asymptomatic ppl(adults) can shed virus

Front 15

what are the clinical sx of rotavirus?

Back 15

1 incubation 2-4 d
2. fever, abd pain, vomit
3. then diarrhea (4-5 d): can lead to severe dehydration
4. no leuks or blood in stool

Front 16

how is the rotazyme dx test for rotavirus performed?

Back 16

1. pt specimen and Ab-bead incubate 3 hrs
2. wash beads, add anti-rota enzyme conjugate, incubate
3. wash, add OPD, incubate
4. OPD +enzyme= YELLOW

Front 17

what are 2 lab tests for rotavirus?

Back 17

Dipstick test
rotazyme test

Front 18

what's the tx for rotavirus?

Back 18

supportive (fluid replacement)
no anti-viral tx

Front 19

how is rotavirus prevented?

Back 19

block fecal-oral trans:
1. gloves/wash hands
2. dispose of contam material (diaper)
3. isolate infected pts

Front 20

is there a vaccine for rotavirus?

Back 20

new vaccine approved last year
RotaTeq

protects against 4 most common types

live, attenuated, oral

Front 21

family and genus of noroviruses?

Back 21

family: Caliciviridae
genus: norovirus

*none have been grown in culture

Front 22

structure of norovirus?

Back 22

non-enveloped
icosahedral capsid
stable
ssRNA (+) genome

Front 23

how does norovirus replicate?

Back 23

ssRNA(+) tsc to single polyprotein which is cleaved into viral polypeptides

Front 24

epidemiology of noroviruses?

Back 24

cause outbreaks in confined populations (cruise ships)
trans by fecal-oral routes
occur worldwide
older children and adults following consumption of sewage-contaminated shellfish

Front 25

pathogenesis of norovirus?

Back 25

similar to rotavirus

Front 26

immunity to norovirus?

Back 26

infection causes production of humoral Abs, but immunity to infection is brief

Front 27

clinical sx of norovirus?

Back 27

similar to rotavirus:
diarrhea w/ nausea, vomit (espec kids)
no bloody stool
fever in ~1/3 pts
incubation period 24-48 hrs
resolves in 12-60 hrs
no serious consequences

Front 28

how is norovirus diagnosed?

Back 28

in stool sample by EM or immunoassay

serology for anti-norovirus Ab

Lab tests usually unnecessary

Front 29

treatment for norovirus?

prevention?

Back 29

supportive (fluid/electrolyte replacement)

good hygiene, avoid shellfish

Front 30

adenovirus

Back 30

2nd to rotavirus as cause of acute diarrhea in kids (5-15% of all gastroenteritis in kids)

types 40 and 41 assoc. w/ diarrhea

difficult to culture

Front 31

which types of adenovirus are associated w/ diarrhea?

Back 31

type 40 and 41

Front 32

how is adenovirus diagnoses?

Back 32

>4x increase in Ab titer
HAI

Front 33

what's the tx for adenovirus?

Back 33

NO antivirals
supportive fluid replacement

Front 34

astroviruses:
where are they found?
what do they cause?

Back 34

ubiquitous in young kids
minor cause of gastroenteritis

Front 35

structure of astrovirus?

Back 35

non-enveloped, stable
ssRNA (+), 3 ORFs

Front 36

how does astrovirus replicate?

Back 36

cytoplasmic
release by cell lysis

Front 37

epidemiology of astrovirus?

Back 37

1. fecal-oral trans
2. worldwide
3. yr round but pk in winter
4. affect yound kids most, elderly,immunosuppressed too
5. epidemics in confined pops

Front 38

how severe is astrovirus infection? Why?

Back 38

mild dz

most adults appear to have protective Abs

Front 39

how is astrovirus diagnosed?

Back 39

clinically: sx like mild form of rotavirus

detect in stool by immunoassay, dot blot hybridization

Front 40

tx and prevention of astrovirus infection?

Back 40

good hygiene

supportive tx