Viral GI infections

Question 1

What clues point to viral gastroenteritis? (4)

Answer 1

No bacterial warning signs such as fever, bloody diarrhea, severe abdominal cramping. Vomiting is prominent. Incubation period is longer than a toxigenic disease. Entire illness is over in less than 72 hours.

Question 2

What are the 5 viruses associated with GI infections?

Answer 2

Rotavirus, calicivirus, enteric adenovirus, astrovirus, hepatitis A and E

Question 3

What is the most common viral cause of acute viral gastroenteritis in adults?

Answer 3

Norovirus, (+)ssRNA, non-enveloped

Question 4

Describe the epidemiology, clinical presentation and transmission of norovirus

Answer 4

Highly infectious, short incubation, short illness
Projectile vomiting, explosive diarrhea
Can be transmitted by fecal/oral route, contact/fomites and aerosols

Question 5

Which genogroups of norovirus generally cause disease in humans?

Answer 5

Mostly in G2 and G4

Question 6

When detecting and characterizing norovirus, which regions of its genome would you use for each?

Answer 6

For detecting: use a region that is more likely to mutate so that you can determine the strain that is causing the illness.
For characterizing: use a region of the genome that is less likely to mutate

Question 7

What makes rotavirus hardy in nature?

Answer 7

It has three capsids

Question 8

How is rotavirus spread and detected?

Answer 8

Spread by oral-fecal or food/waterborne. It is detected by RT-PCR or antigens

Question 9

What are the clinical features of rotavirus? (2)

Answer 9

Low-grade fever and vomiting for 2-4 days. Frequent explosive non-bloody diarrhea.

Question 10

What is the most common cause of viral gastroenteritis in children? What is the second most common cause?

Answer 10

Rotavirus, followed by enteric adenoviruses

Question 11

What is the morphology of enteric adenoviruses? Which types cause gastroenteritis?

Answer 11

Linear dsDNA virus, non-enveloped, types 40 and 41 cause gastroenteritis

Question 12

How are enteric adenoviruses different from noro/rotaviruses? (3)

Answer 12

Longer incubation period, less severe symptoms such as fever and dehydration, longer period of illness

Question 13

What is morphology of astrovirus? (2)

Answer 13

Non-enveloped, (+)ssRNA

Question 14

List the differences between water-borne and blood-borne hepatitis viruses in terms of types, morphology, and whether the infection is acute or chronic

Answer 14

Water-borne: HAV and HEV, (+)ssRNA, non-enveloped, no chronic infection
Blood-borne: HBV, HCV, HDV. Enveloped. May cause chronic disease

Question 15

What hepatitis viruses are RNA viruses and which are DNA?

Answer 15

A, C, E are RNA viruses

B and D are DNA viruses

Question 16

What are 3 clinical features of HAV?

Answer 16

Incubation is 2-6 weeks, usually self limiting with no chronic disease, risk of symptoms increases with age

Question 17

What are the symptoms of HAV and how long do they typically last for?

Answer 17

Fatigue, nausea, vomitting, abdominal pain
Jaundice
Dark amber urine (bilirubin excreted in urine)

Question 18

How is infection of HAV usually detected?

Answer 18

By serology of blood.

Question 19

In regard to serology of HAV, which type of antibody represents an acute infection and a chronic infection?

Answer 19

IgM indicates an acute infection

IgG indicates chronic infection or immunity

Question 20

Describe 3 methods used for the diagnosis of viral gastroenteritis?

Answer 20

Antigen detection: moderate sensitivity (60%), used for rota, noro and adenovirus
Molecular testing: much more sensitive, conventional or RT-PCR
Serology: used for HAV and HEV only