Viral Hepatitis (A and E)

Question 1

Define hepatitis A and E.

Answer 1

Hepatitis caused by infection caused by RNA viruses, hepatitis A (HAV) or hepatitis E (HEV), that follow an acute course without progression to chronic carriage.

Question 2

What is the aetiology of HAV and HEV

Answer 2

• HAV is a picornavirus
• HEV is a calicivirus
• Both are small, non-enveloped single-stranded linear RNA viruses of ~7500 nucleotides , with transmissionby the faecal oral route
• Both replicate in hepatocyte and are secreted into bile
• Liver inflammation and hepatocyte necrosis is caused by the immune response, targeting infected cells by CD8+T cells and natural killer cells
• Histology - inflammatory cell infiltration (neutrophils, macrophages, eosinophils and lymphocytes) of the portal tracts, zone 3 necrosis and bile duct proliferation.

Question 3

How common is HAV and HEV?

Answer 3

• HAV - endemic in the developing world, infection often occurs subclinically. In developed world, better sanitation means that seroprevalence is lower, age of exposure increases and hence is more likely symptomatic.
• Annual UK HAV incidence is 5000 cases (seroprevalence ~5%)
• HEV is endemic in Asia, Africa and Central America

Question 4

What is the incubation period for HAV or HEV?

Answer 4

3-6 weeks

Question 5

What is the typical presentation of HAV and HEV?

Answer 5

Prodromal period - malaise, anorexia (distaste for cigarettes in smokers), fever, nausea and vomiting.

Hepatitis - prodrome followed by dark urine, pale stool and jaundice lasting ~3weeks. Occasionally, itching and jaundice last several weeks in HAV infection (owing to cholestatic hepatitis)

Question 6

What are the signs of HAV and HEV on physical examination?

Answer 6

• Pyrexia
• Jaundice
• Tender hepatomegaly
• Spleen may be palpable (20%)
• Absence of stigmata of chronic liver disease, although some spider naevi may appear transiently

Question 7

What investigations would you do for viral hepatitis ?

Answer 7

Bloods:

• LFTs - v high AST and ALT, high bil, high AlkPhos
• ERS - raised
• Albumin - low
• Platelets - high

Viral serology:

• Hep A -
  
  • Anti-HAV IgM - during acute illness, disappearing after 3-5 months
  • anti-HAV IgG - during recovery phase and lifelong persistence
• Hep E -
  
  • Anti-HEV IgM - raised for 1-4 weeks after onset of illness
  • Anti-HEV IgG
• Hep B and C serology necessary to rule out other causes

Urinalysis - positive for bilirubin and raised urobilinogen

Question 8

Are there vaccines for HAV/HEV?

Answer 8

Only for HAV - passive immunisation with IM human immunoglobulin or active immunisation with attenuated HAV for high risk individuals only

Question 9

How do you manage HAV and HEV?

Answer 9

• Bed rest and symptomatic treatment (e.g. antipyretics and antiemetics)
• Colestyramine for severe pruritus

PREVENTION AND CONTROL:

Public health - safe water, sanitation, food hygiene standards, both notifiable diseases, personal hygiene and sensible dietary precautions when travelling

Immunization (HAV only) - passive immunisation with IM human Ig effective for short period only. Active immunisation with attenuated HAV vaccine offers safe and effective immunity for those travelling to endemic areas, high risk individuals (e.g. residents of institutions)

Question 10

How is the spread of HAV/HEV prevented?

Answer 10

Public health measures such as:

• clean water
• sanitation
• food hygiene
• notifiable diseases - both HAV and HEV
• sensible dietary precautions when travelling

Question 11

What are the complications of HAV/HEV?

Answer 11

Fulminant hepatic failure develops in 0.1% cases of HAV, 1-2% of HEV but up to 20% of pregnant women.

Cholestatic hepatitis with prolonged jaundice and pruritus may develop after HAV infection.

Post- hepatitis syndrome - continued malaise for weeks to months

Question 12

What is the prognosis of HAV/HEV?

Answer 12

• Usually recover in 3-6 weeks
• Occassionally relapse during recovery
• No chronic sequelae
• Fulminant hepatic failure carries 80% mortality

Question 13

Who is most at risk from HEV infection?

Answer 13

High mortality in pregnant women - unexplained. Mainly with genotype 1.

Complications include:

• fulminant hepatic failure
• obstetric complications (e.g. eclampsia and haemorrhage);
• 25% maternal mortality & high perinatal infant mortality

NB: chronic hep E may occur in the immunocompromised

Question 14

What are the non-hepatic complications of HEV?

Answer 14

• CNS disease
  
  • Bell’s palsy
  • Guillain Barre
  • other neuropathy
• Chronic infection

Question 15

What are the most common routes of transmission of HEV?

Answer 15

• Shellfish consumption
• blood transfusion
• Sausages
• pig liver consumption

Faeco oral is most common. Although HEV is generally uncommon with little person-to-person spread