V1: Hepatitis Viruses

Question 1

Define hepatitis

Answer 1

Inflammation of the liver without a pinpoint specific cause

Question 2

What can hepatitis be caused by

Answer 2

• liver injury by toxin
• liver damage by interruption of the organ’s blood supply
• an attack of the immune system (autoimmunity)
• trauma to the abdomen in the area of the liver

Question 3

What happens in acute infectious fevers compared to in hepatitis

Answer 3

The virus infects the kuppfer cells of the reticuloendothelial system and so liver damage is avoided

The main target of hepatitis viruses are the hepatocytes

Question 4

How can people be hepatitis carriers

Answer 4

Carriers evolve from acute infections which are mild and anicteric and the patient may be asymptomatic but the infection is detectable on blood screening, they might also suffer long term sequelae of persistent infections

Question 5

Features of HAV

Answer 5

RNA enterovirus transmitted

• faecal-orally (children, group homes, water/food contamination, shellfish)
• oral anal sexual activity

Incubates for 10-15 days and causes mild flue like signs and symptoms

Immune globulin within two weeks of exposure

Question 6

What are the clinical features of HAV

Answer 6

Jaundice (more likely when the patient is >14)
Fulminant hepatitis
Cholestatic hepatitis
Relapsing hepatitis
It can cause prolonged illness for 6 months but it is typically short periods of illness which do not cause chronic liver disease

Question 7

Outline the pathogenesis of HAV

Answer 7

Virus replicates in hepatocytes and passes through the bile duct into the intestine where it is shed in large quantities

Damage to liver function results in raised liver enzymes

Question 8

How is the spread of HAV controlled

Answer 8

1. Passive protection = human normal immunoglobulin
2. Vaccination = one serotype, formalin inactivated vaccine prepared from HAV grown in human diploid cells
3. Very high hygiene standards

Question 9

Features of HBV

Answer 9

DNA virus which transmits through blood, skin/mucus membrane contamination with blood/serous fluid, semen and vaginal fluid

• IVDU (Parenteral)
• Sexual
• Perinatal (at/during birth)

Incubation = 48-180 days and typically affects young adults (20-39)

Question 10

What complications can arise with HBV

Answer 10

Chronic hepatitis (chronic persistant/chronic active)
Cirrhosis 
Liver cancer (hepatocellular carcinoma)

Question 11

Outline the morphology and replication of HBV

Answer 11

It is a DNA virus (double stranded and circular) and DNA polymerase is involved in replication

• HBcAg = core antigen (not detectable)
• HBeAg = active virus antigen (Dane particles = infective virions)
• HBsAg = surface antigen

When replicating, HBV uses an RNA intermediate and reverse transcriptase. There is a high mutation rate, but the small genome prevents much genetic variability

Question 12

What are the clinical features of HBV

Answer 12

Jaundice
Chronic infection
Can cause premature mortality from chronic liver disease

Question 13

How is the spread of HBV controlled

Answer 13

Infection control: sterilisation and aseptic technique
PPE
Vaccination/ immunisation
Passive prophylaxis immunisation post exposure
Safe sex

Question 14

What treatments are available for HBV

Answer 14

1. Interferon (HBeAg+ve with chronic acute hepatitis)
2. Lamivuidine (relapse on drug cessation)
3. Adefovir (less likely to develop resistance)
4. Entecavir (most powerful antiviral)

Question 15

Features of HDV

Answer 15

Defective RNA virus which is seen with HBV in coinfection or superinfection and it has the same routes of transmission

Incubation = 14-56 days and the patient is usually asymptomatic

Question 16

How is hepatitis D prevented

Answer 16

HBV-HDV coinfection: pre/post exposure prophylaxis to prevent HBV infection

HBV-HDV superinfection: education to reduce risk behaviours among people with chronic HBV infection

Question 17

Features of HCV

Answer 17

It is an RNA virus which is transmitted by skin/mucus exposure with blood or serum

Incubation period = 21-140 days

Most cases develop into chronic hepatitis and it is the main cause of cirrhosis and liver cancers (severe signs and symptoms)

Question 18

What are the risk factors associated with HCV

Answer 18

• Transfusion/ transplant from infected donor
• IVDU
• Heamodialysis (many years on treatment)
• Accidental injuries with needles/sharps
• Getting a tattoo/ piercing with unsterilised tools
• Sexual/ household exposure to anti-HCV-positive contact
• Multiple sex partners
• Birth to HCV-infected mother

Question 19

What are the clinical features of HCV

Answer 19

Jaundice
Chronic hepatitis
Persistant infection
No protective antibody so no immunity

Question 20

How is HCV controlled

Answer 20

There is no vaccine but HCV can be detected by screening blood donors and blood products, and needle exchange schemes can help control

Question 21

What are the treatments for HCV

Answer 21

1. Interferon (patties with active hepatitis - relapse on withdrawal)
2. Ribavirin

Combination is more effective that interferon alone

Question 22

Features of HEV

Answer 22

It is a waterborne RNA virus which is transmitted via contaminated water

Incubation = 15-64 days

Question 23

What are the clinical features of HEV

Answer 23

Similar to HAV but infection is acquired in adolescence/adulthood compared to infancy and there is a longer incubation time

Women infected in the late stages of pregnancy have a mortality rate of 20%

Question 24

How is HEV spread prevented

Answer 24

• Avoid drinking water of unknown purity

- Cook seafood fully