0226 - Viral Hepatitis Flashcards
What are the hepatitis viruses?
Viruses for which the liver is the predominant site of replication, and that cause inflammation and hepatocyte injury (acute hepatitis).
HBV, HCV, and HDV can evade immune clearance and become chronic, leading to cirrhosis, and hepatocellular carcinoma.
Describe the enteral hepatitis viruses (stay acute)
HAV - RNA virus, non-enveloped
HEV - RNA virus, calicivirus
Describe the blood-borne hepatitis viruses (can become chronic)
HBV - DNA virus, enveloped (hepadnavirus)
HCV - RNA virus, enveloped, flavivirus (hepacivirus)
HDV - RNA virus, incomplete (viroid)
Name at least 5 signs and symptoms of acute hepatitis.
Anorexia Nausea Vomiting Bilirubinuria Jaundice Tender, soft liver (RUQ pain rare) Malaise and fatigue NOT fever, rigors, and sore throat
What are the differences between acute and chronic hepatitis
Acute hepatitis is generally self-limiting.
Chronic hepatitis may present with no signs or symptoms and normal LFTs if well-compensated (otherwise look for stigmata of chronic liver disease). Acute hepatitis presents with signs and symptoms, ALT >500, and serology results.
Name 4 differential diagnoses for acute hepatitis
Other viruses (EBV, CMV, H. Simplex, HIV, Parvo) Hepatotoxicity (paracetamol/adverse drug reaction) Other inflammation (Acute cholecystitis, cholangitis, liver abscess (pain, fever/rigor, leukocytosis) Ischaemic hepatitis (heart failure/shock - ALT >>1,000)
Which liver diseases are usually chronic but may present with acute symptoms?
Hepatitis B (flare - potentially lethal) Alcoholic hepatitis (history, stigmata) Non-alcoholic steatohepatitis (NASH) Autoimmune hepatitis Wilson’s disease (children/young adults)
Name two clinical outcomes of chronic hepatitis
Cirrhosis
Hepatocellular Carcinoma
Death
Briefly outline HAV infection
Simple enteric viral infection, incubation 3-6 weeks.
Faeces not infectious 7-10 days after onset of jaundice
Often asymptomatic, but can present with significant acute signs and symptoms
Severity increases with age.
How is HAV infection diagnosed?
IgM anti-HAV
Outline the HAV vaccination
Live, attenuated virus, given as 2 injections over 6 months.
Safe, but expensive, so not generally cost effective (except for community outbreaks)
Can be combined with HBV vaccine
Briefly outline the virology of HBV
DNA virus that replicates via RNA template (reverse transcriptase).
Causes acute or chronic hepatitis
Infected liver elaborates HBsAg
Many different genotypes
How can HBsAG and HBV DNA diagnose HBV?
HBsAg most useful for acute hepatitis - it’s the surface antigen
HBV DNA essential to assess chronic HBV - it gives an indication of viral load.
Briefly outline the epidemiology of HBV
350 million chronic worldwide - Africa, Asia, Arctic America
9th leading cause of death (HCC)
In Australia, 90-150,000, 75% Asian
What are some risk factors for HBV?
Multiple sexual partners Healthcare workers Newborns of HBsAg+ mothers Young children in contact with HBsAg Injecting drug users
How can HBV be prevented?
HBV vaccine - contains HBsAg
96% humoral immunity
>90% reduction in acute HBV
Universal infant vaccination
What is the clinical spectrum of HBV?
From silent to death.
40-50% die of cirrhosis or HCC (~25%) - unpredictable course
Risk correlates with serum HBV DNA >2,000 (Key test)
Can flare lethally and with rapid progression
How can HBV be treated?
Antivirals - Entecavir and Tenofovir to suppress replication.
Aim for life-long suppression of HBV replication, reversing fibrosis, preventing cirrhosis and HCC.
Effective treatment prevents decompensation of cirrhosis, and lowers risk of HCC by >50%
How can you tell if someone has been vaccinated or infected by HBV?
Test for HBcAg - core antigen.
Vaccine only contains HBsAg.
Key learning points [CRS]
HAV and HEV are enteric, cause acute hepatitis (HEV geographically restricted)
HBV and HCV are blood-borne (+ sexual for HBV)
Acute Hepatitis is generally self-limiting, acute liver failure rare (increased risk with age and HBV)
HBV and HCV can cause chronic hepatitis, leading to cirrhosis and liver cancer
HAV, HBV are vaccine-preventable
Preventing blood contamination is most important for HCV prevention
Chronic HBV and HCV are both treatable
Treating chronic viral hepatitis can prevent liver related death from cirrhosis and HCC
Key learning points for treating HBV [HLP]
Entecavir and tenofovir now commonly used
Both suppress viral replication by median 5 log (from 10^7 to <100)
ALT normalises 3-6 months
Drug resistance rare
Surveillance for HCC (6 monthly ultrasound, AFP).
