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Viral Hepatitis (Y4)
Terms in this set (36)
Viral hepatitis must be considered in anyone presenting with what type of liver blood tests?
Hepatitic - high transaminases, 200-2000U/L in acute infection, lower/fluctuating in chronic infection.
What are the clinical features of acute infection?
Nonspecific prodromal illness: headache, myalgia, arthralgia, nausea + anorexia precedes jaundice by ~2wks.
Dark urine + pale stools may precede jaundice.
V+D may follow, ab discomfort common.
What is hepatitis A?
Highly infectious, faecal-oral.
1 month incubation.
Acute disease, common + asymptomatic in children.
>14 yrs, most get jaundice.
No chronic infection state (0.1% acute liver failure).
What are the investigations for HAV?
very high ALT up to 1000
Why is anti-HAV important for diagnosis?
HAV is present in the blood only transiently during incubation.
What are the two types of anti-HAV?
IgM: primary immune response, present in blood at onset of acute illness, diagnostic.
IgG: indicates immunity to HAV, previous infection, no diagnostic value.
Who should be immunised against HAV?
Chronic HBV/HCV patients.
Those at particular risk - close contacts of infected, elderly, other major disease, pregnant.
When can immune serum globulin be used for HAV?
Can provide protection if given soon after virus exposure.
Can be effective in an outbreak eg school - prevents spread.
What is hepatitis B?
double stranded DNA + DNA polymerase enzyme
What circulates in the blood during HBV infection?
Dane particles and hepatitis B surface antigen (HBsAg).
What happens with HBV in immune competent individuals?
acute infection, 95% clear virus, very few cases become fulminant.
What is the commonest cause of acute HBV?
What is the definition of chronic HBV? Why is it hard to clear?
Presence of HBsAg for > 6 months
Covalently linked circular viral DNA lives in human nucleus - protected from immune system.
When are chronic HBV infections usually acquired?
At birth (vertical transmission) or early childhood in the immunotolerant phase - often asymptomatic.
What can chronic HBV lead to?
Cirrhosis or hepatocellular carcinoma.
What causes liver injury in HBV infection?
The immune response to viral antigens on infected hepatocytes.
How is HBV infection investigated/monitored?
HBV antigens + antibodies.
PCR measurement of viral load.
What is hep B surface antigen (HBsAg) an indicator of?
Active infection: -ve test makes HBV unlikely.
When is HBsAg present in the blood?
Late in the incubation period - before prodomal phase of acute hepatitis.
Usually lasts for 3-4 weeks or up to 5 months.
Is HBsAg present in acute liver failure from hep B? What provides evidence of recent infection?
No - damage mediated by viral clearance.
Hepatitis B core IgM.
When does antibody to HBsAg appear?
After about 3-6 months.
Is hep B core antigen (HBcAg) found in the blood? What about the antibody?
No - but the antibody (anit-HBc) appears early - IgM then IgG.
What is hep B e antigen (HBeAg) an indicator of? When is the antibody present?
Viral replication - appears transiently at the outset, followed by anti-HBe.
What blood markers are present in chronic HBV?
HBsAg + anti-HBc
Usually HBeAg or anti-HBe also present indicating level of viral replication in liver, except in HBeAg-negative chronic hep B.
What is HBeAg-negative chronic hepatitis B?
Patients with a mutation in the pre-core protein - cannot secrete e antigen.
High levels of viral replication, serum HBV-DNA and hepatic necroinflammation.
Respond differently to antivirals.
Which marker distinguishes type B hepatitis and hep B infection?
ALT - if increased, then hepatitis.
If not - infection.
When can hep B reactivation occur?
Immunosuppression - haematological or iatrogenic.
Should always give prophylaxis before immunosuppression if past hep B infection.
Is there a hep B vaccine?
Yes - now routine immunisation in UK.
What is hepatitis D?
RNA-defective virus that requires co-infection with HBV.
What is hepatitis C? Does is cause acute or chronic infection?
Acute symptomatic infection rare - 80% become chronically infected. 1/20 become cirrhotic in 20 yrs.
No passive or active protection = no vaccine.
What is the most common cause of hep C in the UK?
IV drug use
What LFTs are seen in hep C?
normal or fluctuating serum transaminases between 50-200U/L. Jaundice is rare - appears only in end-stage cirrhosis.
What is the management of hep C?
Direct-acting antivirals (DAAs).
99% success in clearing virus in 8-12 weeks - sustained virological response (SVR).
Failsafe for DAA failures - 98% success.
No difference in treatment/success for HIV +ve or post-transplant.
What is hep E?
Usually endemics with contaminated water in India + Middle East.
Prevalence increasing in Europe.
How is Hep E spread in Europe + UK?
Faecal-oral route. Spread by uncooked pork/meat. Most common cause of acute viral hepatitis.
Does hep E cause acute or chronic infection?
Usually self-limiting acute hepatitis, IgM antibody positive.
May develop to chronic infection in immunocompromised.
Infection during pregnancy - acute liver failure with high mortality.
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