Viral Gastroenteritis

Question 1

Define viral gastroenteritis

Answer 1

Inflammation of the stomach and intestines caused by viruses and characterised by diarrhoea and vomiting

Question 2

Who is at higher risk of viral gastroenteritis?

Answer 2

• children under 5
• old age (esp if living in a nursing home)
• immunocompromised

Question 3

List the viruses that cause gastroenteritis

Answer 3

• norovirus and sapovirus (calciviridae)
• rotavirus
• adenovirus 40 and 41
• astrovirus

Question 4

What individuals are affected by norovirus/sapovirus?

Answer 4

• all ages + healthy individuals
• young + elderly can have serious infection

Question 5

What individuals are affected by rotavirus/adenovirus/astrovirus

Answer 5

Mainly:
- children under 2
- elderly
- immunocompromised
(Because immunity is built up over time in immunocompetent + adults)

Question 6

Describe the structure of norovirus

Answer 6

• calciviridae family
• non-enveloped, single stranded RNA virus
• 3 (of 10) genogroups affect humans = GI, GII, GIV
• GII-4 most common

Question 7

Describe the features of transmission of norovirus

Answer 7

• person-person (faecal-oral, aerosolised)
• food-borne
• water
• infectious dose very small
• stable + can remain viable for long time in environment
• 24-48 hrs incubation
• can shed for up to 3 weeks after infection

Question 8

Describe the clinical features of norovirus

Answer 8

• asymptomatic but most have symptoms
• vomiting
• non-bloody diarrhoea
• nausea
• abdominal cramps
• headaches, muscle aches
• low-grade fever
• dehydration in young and elderly
  (Usually lasts 12-60 hours)

Question 9

Describe the complications of norovirus

Answer 9

• childhood hospitalisation
• illness in hospital outbreaks last longer + have increased risk of mortality
• (because patients are usually more frail and have an underlying illness)
• chronic diarrhoea + virus shedding (up to 2 years) in organ transplant patients + bone marrow patients

Question 10

List the possible treatments for norovirus

Answer 10

Symptomatic therapy:
- oral and/or IV fluids
- antispasmodics
- analgesics
- antipyretics

Question 11

Describe the immunity period associated with norovirus infection

Answer 11

• 6-14 weeks
• a vaccine has not been able to be created due to issues with culturing and limited understanding of immunity

Question 12

How can norovirus infection be kept under control in the hospital setting

Answer 12

• isolation/cohorting
• exclude symptomatic staff until symptom free for 48 hours
• do not move or admit new patients (until last case asymptomatic for 48 hrs)
• thorough cleaning with dilute hypochlorite/hot soapy water
• patient/visitor awareness

Question 13

Describe the structural features of rotavirus

Answer 13

• reoviridae family
• double stranded, non-enveloped RNA virus
• 5 predominant strains G1-4, G9
• virus contains 11 strands of RNA so has the potential for antigenic variation (replicative changes)
• stable in environment and fairly resistant to hand washing

Question 14

Describe the transmission of rotavirus

Answer 14

• low infectious dose
• person-person (faecal-oral, fomites)
• food + water spread possible
• viral shedding up to 10 days after in stool (can be longer in immunocompromised)

Question 15

Describe the clinical features of rotavirus

Answer 15

• incubation period 1-3 days
• manifestation depends on if 1st infection or reinfection (1st more severe)
• watery diarrhoea, abdominal pain, vomiting, loss of electrolytes (dehydration)
• symptoms can last 3-7 days

Question 16

List the possible complications of rotavirus

Answer 16

• severe chronic diarrhoea
• dehydration
• electrolyte imbalance (due to fluid loss)
• metabolic acidosis
• immunodeficient children can have more severe or persistent disease

Question 17

Describe how immunity is generated in rotavirus

Answer 17

• antibodies against VP7, VP4 and secretory IgA (viral proteins)
• 1st infection does not lead to permanent immunity
• each subsequent infection leads to further reductions in severity

Question 18

Rotavirus vaccine

Answer 18

• derived from a virus which was isolated and attenuated by serial cell culture passage (to not cause illness but induce immunity)
• part of childhood immunisation schedule

Question 19

Describe the features of adenovirus

Answer 19

• adenoviridae family
• double stranded DNA virus
• > 50 serotypes that cause disease (40 and 41 cause gastroenteritis)
• symptoms: fever + watery diarrhoea
• supportive treatment

Question 20

Describe features of astrovirus

Answer 20

• astroviridae family
• single stranded, non-enveloped RNA virus
• causes less severe gastroenteritis
• usually causes sporadic cases (outbreaks usually in young children)

Question 21

Describe the process of diagnosing viral gastroenteritis

Answer 21

PCR which detects the DNA/RNA in a vomit or stool sample