Viral GI Infections

Question 1

List the 5 main viruses causing GI infection.

Which ones occur in healthy people?
Which ones occur in the young/elderly/immunocompromised?

Answer 1

AFFECTING HEALTHY PEOPLE:
Norovirus
Sapovirus

AFFECTING THE YOUNG/ELDERLY/IMMUNOCOMPROMISED:
Rotavirus
Adenovirus 40 and 41
Astrovirus

Question 2

List 4 viruses which replicate in the gut but do NOT cause GI disease.

Answer 2

Poliovirus
Other enteroviruses
Adenoviruses
Hepatitis A

Question 3

What type of virus is sapovirus?

Answer 3

Calicivirus

Question 4

What type of virus is norovirus?

Describe its structure. (3)

Answer 4

Non-enveloped
ssRNA
Antigenic variation

Question 5

Describe the 6 types of norovirus.

Which ones affect humans? (3)

Answer 5

Groups 1-6

AFFECTING HUMANS:

• Group 1
• Group 2
• Group 4

Question 6

How do you diagnose norovirus infection? (2)

Answer 6

PCR
-Testing for viral DNA

Bristol stool chart
-Types 6 or 7

Question 7

Describe the Bristol stool chart. (7)

Answer 7

Type 1 - separate hard lumps
Type 2 - lumpy and sausage like
Type 3 - sausage shape with cracks in the surface
Type 4 - smooth, soft sausage or snake
Type 5 - soft blobs with clear cut edges
Type 6 - mushy consistency with ragged edges
Type 7 - liquid

Question 8

Describe the epidemiology of norovirus. Consider:

a) Transmission (3)
b) Infectious dose
c) Infectious period
d) Outbreaks

Answer 8

TRANSMISSION:
Person-person
Contaminated food
Contaminated water

INFECTIOUS DOSE:
10-100 (very low)

INFECTIOUS PERIOD:
From: Onset of symptoms
To: 48 hours after symptoms stop

OUTBREAKS:
Common

Question 9

Describe the clinical features of a norovirus infection. (7)

Answer 9

Asymptomatic
Vomiting/nausea
Diarrhoea
Abdominal pain
Headache
Muscle aches
Fever (rare)

Question 10

Describe 2 complications of norovirus infection.

In which patient groups do these occur?

Answer 10

Dehydration

• Young patients
• Elderly patients

Chronic diarrhoea and virus shedding

• Solid organ transplants
• Bone marrow transplants

Question 11

Describe treatment of norovirus infection. (4)

Answer 11

Symptomatic therapy:

1. Oral/IV fluid replacement
2. Antispasmodics
3. Analgesics
4. Antipyretics

Question 12

Describe infection control measures needed for norovirus infection. (6)

Answer 12

Isolation/cohorting
Exclusion of symptomatic staff
Do not admit new patients
Thorough cleaning of environment 48 hours after last case
Patient/visitor awareness
Hand hygiene

Question 13

What type of virus is rotavirus?

Describe its structure. (2)

Answer 13

Reovirus

dsRNA
Segmented (11 strands)

Question 14

Describe the epidemiology of rotavirus. Consider:

a) At risk populations (3)
b) Infectious dose
c) Infectious period
d) Outbreaks

Answer 14

AT RISK POPULATIONS:
Children under 2 yo
Elderly
Immunocompromised patients

INFECTIOUS DOSE:
10-100 (very low)

INFECTIOUS PERIOD:
While symptoms are present

OUTBREAKS:
Frequent in paediatric wards

Question 15

What is the incubation period for rotavirus?

How long does a rotavirus infection normally last?

Answer 15

Incubation period: 2 days

Duration: 3-8 days

Question 16

Describe the symptoms of rotavirus infection. (5)

Answer 16

Anorexia
Low grade fever
Watery diarrhoea
Vomiting
Abdominal pain

Question 17

Describe the treatment for rotavirus infection. (1)

Answer 17

Rehydration therapy

Question 18

Can you get immunity to rotavirus?

How?

Answer 18

Yes

Rotavirus vaccine (Rotarix)

Question 19

Is the rotavirus vaccine live or not?

Answer 19

Live

Question 20

Describe the infection control measures needed for rotavirus. (4)

Answer 20

Isolation/cohorting
Do not admit any new patients
Thorough cleaning of the ward
Patient/visitor awareness

Question 21

How do you diagnose adenovirus? (3)

Answer 21

PCR (viral DNA)

Bristol stool chart:
-Types 6 or 7

ELISA test (viral antigens)

Question 22

Can you get immunity to norovirus?

How?

Answer 22

Yes - but only lasts <1 year

Previous infection