Viral Gastroenteritis

Question 1

Does viral gastroenteritis present with watery or bloody diarrhea? Does vomiting usually precede or follow?

Answer 1

ACUTE onset watery diarrhea
(w/o mucous/blood like bacteria)

Vomiting often precedes if it is present

Question 2

Viral gastroenteritis:

• short or long periods?
• duration of symptoms?
• why does it persist even after you poo?
• stable or unstable?
• seasonal or year round?

Answer 2

Short incubation period

Short duration of sx

Prolonged shedding in stool
- can infect others

Stable: lasts for days on surfaces
- highly transmissible

Seasonal: winter

Question 3

How common are virus causes of gastroenteritis?

List common types of virus that cause it.

Answer 3

virus cause >75% of gastroenteritis

1. Caliciviruses
   - norovirus
   - sapovirus
2. Rotavirus
3. Enteric adenovirus
   - lots of different serotypes

Question 4

Vaccines for which virus is available against gastroenteritis?
Name them

Answer 4

rotavirus

1. RotaTeq (RV5)
   - pentavalent live bovine
2. Rotarix (RV1)
   - monovalent live hu

Question 5

Norovirus

• DNA or RNA virus?
• enveloped?
• virulence factor?

Answer 5

small round ssRNA virus

• non-enveloped (naked)
• viral encoded protease cleaves viral protein –> replication

Question 6

how many indiv infected with norovirus are asymptomatic?

Incubation + duration of sx?

Answer 6

1/3 asym (but can still shed virus in stool)

Fastest on and fastest off *
Incubation: 15 hours-2 days
Duration: 1-2 days

Question 7

Most common cause of diarrheal outbreaks in older children and adults?

Answer 7

Norovirus

- also the 2nd most common cause of diarrhea in young children

Question 8

Norovirus seasonality

Answer 8

year round

- with winter predom.

Question 9

Norovirus immunology

Answer 9

short lived ~6 months

• frequent antigenic shift
• strain diversity

Host ab confers short-term protection

Question 10

What gene can allow some indiv to be innnately resistant against norovirus?

Answer 10

FUT2

Question 11

Rotavirus comes from which viral family?

Answer 11

Reoviridae

*gobstopper vrus

(note that noravirus comes from the calicivirus family)

Question 12

Rotavirus

• DNA or RNA?
• enveloped?

Answer 12

dsRNA
nonenveloped 
- but has 3 protein shells
1. outer capsid layer:
2. inner capsid layer
3. innermost

Question 13

These layers of the rotavirus protein shells (not envelop) confer which virulence?

1. outer capsid layer:
2. inner capsid layer
3. innermost

Answer 13

1. outer capsid layer:
   - acid stability
   - VP7 with VP4spikes: neutralizing ab
2. inner capsid layer:
   - VP6: major rotavirus group antigen
3. innermost
   - VP2

Question 14

Reassortment

Answer 14

allows introduction of segments from animal rotavirus into human rotavirus
–>
EPIDEMICS

Question 15

Rotavirus enterotoxin

Answer 15

NSP4
- destabilizes membranes -->
cell death
- mobilizes intracellular Ca2+ -->
activ. signal transduction pathway to transport from ER

Question 16

Incubation period and duration of Rotavirus

Answer 16

Incubation period: 1-3 days

Peak viral shedding on day 3

Symptoms: 4-8 days
- more severe than noravirus

*but still a self limiting disease

Question 17

Single most important cause of severe infantile gastroenteritis world wide

Answer 17

rotavirus

• preventable w/ vaccine
• treatable by ORT

*peak at age 6-24 mo

Question 18

Seasonality of rotavirus

Answer 18

predom: winter

- year round in tropics