Viral Hepatitis Flashcards

1
Q

Hepatitis - causes

A
  • viral (A-E)
  • alcohol-related liver disease
  • autoimmune hepatitis
  • hereditary (wilson’s, haemochromatosis)
  • NAFLD
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2
Q

Viral hepatitis - general pathophys

A
  • viral proteins presented by MHC I on hepatocytes
  • cytotoxic reaction by CD8+ T cells
  • apoptotic councilman bodies on histology
  • high transaminases (ALT > AST) in viral hepatitis
    (unlike alcoholic hepatitis where AST > ALT)
  • atypical lymphocytes
  • high bilirubin (both c.b. and u.c.b.) and urobilinogen
  • infection >6 months = chronic hepatitis
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3
Q

Viruses - general features

A
  • A + E = ACUTE only; rest can be acute or chronic
  • chronic = approx 90% Hep C and 10% Hep B
  • Hep B is a double-stranded DNA virus; rest are single-stranded RNA
  • B, C, D are enveloped (lipid outer layer), A + E are “naked”
  • fulminant hepatitis = can occer in Hep A, B, C, E
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4
Q

Clinical presentation (general)

A
- often asymptomatic
If symptomatic:
- anorexia, N+V
- Jaudice +/- dark urine, pale stools
- malaise
- fever
- RUQ pain
- hepatomegaly +/- ascites
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5
Q

Hepatitis B - general features

A
  • transmission: percutaneous and permucosal routes. E.g. IVDU, needle sticks, vertical (mother to baby) and sexual transmission
  • common in endemic regions - Asian or African
  • most cases are acute
  • only 20% are chronic (more risk the younger you are)
  • linked to liver cancer
  • sometimes a/w arthritis and erythema nodosum
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6
Q

Hepatitis B - antigens (bad guys)

https://www.youtube.com/watch?v=6yKIpQElh-4

A
  • Surface antigen (HBsAg) = most relevant one; part of envelope; signifies active infection (either early acute or chronic infection) or recent vaccination
  • Core antigen (HBcAg) = part of capsid –> undetectable in serum, so no test for it
  • E antigen (HBeAg) = signifies replication of virus, so active (acute or chronic) and highly infectious. If +ve in chronic, needs treatment
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7
Q

Hepatitis B - antibodies

A
  • Surface antibody (Anti-HBs or HBsAb) = against surface antigen (IgM early on, then IgG); +ve if fully vaccinated or had an acute infection that resolved. Not present during an active chronic infection.
  • Core antibody (Anti-HBc or HBcAb) = against core antigen (IgM early on, then IgG); found during and after the resolution of an acute infection, or during a chronic infection. Also can be found during window period
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8
Q

Hep B - window period

A
  • short period during acute infection or early vaccination
  • abscence of surface antigen and antibody in blood (as they are bound together) - antigen 1:1 antibody ratio
  • HBeAg or Anti-HBc may be present
  • one could miss diagnosis as no surface Ag and Ab are present, so look out for E antigen or core antibody
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9
Q

Hep B - post window period (scenarios)

VACCINATION

A

Vaccination
+ve HBsAb (means they are protected)
-ve HBsAg
-ve HBcAb (were not infected in the first place)

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10
Q

Hep B - post window period (scenarios)

RESOLUTION OF ACUTE INFECTION

A

Resolution of acute infection
+ve HBsAb (antibody fought the infection)
-ve HBsAg (antigen is now depleted)
+ve HBcAb

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11
Q

Hep B - post window period (scenarios)

PROGRESSION TO CHRONIC INFECTION

A

Chronic infection
+ve HBsAg (antigen still high so infected)
-ve HBsAb (antibody did not fight the infection)
+ve HBcAb

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12
Q

Hepatitis C - general features

A
  • transmission = percutaneous (parenteral, sexual, vertical). RFs as per Hep B + unsafe medical procedures, Hx of transfusion or transplant
  • most common form of viral hepatitis (over 70 million cases worldwide)
  • gold standard test is HCV RNA test with PCR: detects viral load in blood early on
  • whilst patients will eventually develop anti-HCV antibodies it should be remembered that patients who spontaneously clear the virus will continue to have anti-HCV antibodies
  • Ishak score used to assess severity of chronic hep C (based on biopsy)
  • can progress to cirrhosis and liver cancer (risk higher in alcoholics or co-infected with HIV)
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13
Q

Hepatitis A - general features

A
  • transmission = fecal-oral route
  • RF: living or TRAVELLING to an endemic area (eg Africa, some parts of Asia), close contact with infected person, exposure to a known food-borne outbreak, contaminated water
  • acute ONLY
  • HAV IgM = active infection
  • HAV IgG = resolved or vaccinated
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14
Q

Hepatitis E - general features

A
  • transmission = fecal-oral route
  • widespread in Southeast Asia, northern and central Africa, India, and Central America
  • exposure to a known food-borne outbreak esp. undercooked seafood, contaminated water
  • acute ONLY
  • HEV IgM = active infection
  • HEV IgG = resolved
  • no vaccine available
  • can be severe in pregnant women and lead to fulminant hepatitis (massive necrosis of liver parenchyma and acute yellow atrophy)
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15
Q

Hepatitis D - general features

A
  • trasmission: similar to HBV - needs HBV to infect
  • acute or chronic
    Two patterns of infection
    1. Coinfection (at the same time as HBV)
    2. Superinfection (infects later) - more severe
  • either IgM or IgG indicate active infection (IgG is not protective in this case)
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16
Q

Hepatitis Vaccination

A
  • available for Hep A and B
  • Hep A vaccine: not routinely offered in the UK, only high risk people eg close contacts or travellers. Can be live-attenuated or inactivated
  • Hep B vaccine: routine in NHS at 8, 12 and 16 weeks. It is an inactivated vaccine
17
Q

Investigation (general)

A
  • LFTs
  • FBC (microcytic anaemia and/or thrombocytopenia)
  • U+Es (might have hyponatremia due to oedema)
  • coagulation profile (normal or elevated)
  • serology (antigens, antibodies)
  • consider US, liver biopsy and special tests
18
Q

Investigations (specific)

A

Hep B

  • serum HBsAg, anti-HBs, anti-HBc, HBeAg
  • HBV DNA (PCR) for viral load
  • liver US, biopsy or AFP to rule out cancer

Hep C

  • serum antibodies
  • enzyme immunoessay for HCV IgG
  • recombinant immunoblot assay (more specific)
  • nucleic acid amplification tests (NAATs) including PCR
  • viral genotyping prior to treatment
  • screen for liver cirrhosis (Transient elastography)

Hep A

  • serum anti-HAV IgM (or IgG)
  • electron microscopy of stool and body fluids
  • NAATs for RNA detection
19
Q

Treatment (general)

A
  • acute infection = supportive care only (eg analgesia, anti-emetics)
  • chronic infection = start antiviral therapy (eg entecavir) or interferon injections (peginterferon alfa 2a) for Hep B
  • severe = consider liver transplant
  • remember vaccination for hep A and B
20
Q

Lifestyle measures

A
  • avoid alcohol and smoking (reduce cancer risk)
  • avoid sharing items that might be contaminated
  • avoid unprotected sexual intercourse
  • avoid sharing needles and other drug paraphernalia
  • don’t donate blood, or carry an organ donor card
  • infant should be immunized against Hep B from birth
21
Q

Hepatitis - complications

A
  • fulminant hepatic failure (can present with jaundice, coagulopathy, and hepatic encephalopathy)
  • cirrhosis
  • hepatocellular carcinoma (Hep B, C)
  • glomerulonephritis (Hep B, C)
  • skin conditions eg lichen planus (Hep C)
  • rheumatological eg myalgia, fatigue, arthralgias, and arthritis (Hep C or B)
22
Q

Hepatitis C - complications

A
  • rheumatological problems: arthralgia, arthritis
  • eye problems: Sjogren’s syndrome
  • cirrhosis (5-20% of those with chronic disease)
  • hepatocellular cancer
  • cryoglobulinaemia: typically type II (mixed monoclonal and polyclonal)
  • porphyria cutanea tarda (PCT): especially if there are other factors such as alcohol abuse
  • membranoproliferative glomerulonephritis
23
Q

Hep B in pregnancy

A
  • all pregnant women are offered screening
  • babies born to mothers who are chronically infected or mothers who’ve had acute hepatitis B during pregnancy should receive a complete course of vaccination + hepatitis B immunoglobulin
  • there is little evidence to suggest caesarean section reduces vertical transmission rates
  • hepatitis B cannot be transmitted via breastfeeding (in contrast to HIV)