Hepatitis viruses Flashcards by Sarah PETERSEN

Transmission of Hep A

faecal-oral

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Clinical features of Hep A

incubation period = 2-7 days
many subclinical infections
illness usually brief and self limiting
mortality <0.2%
no chronic disease

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Diagnosis of Hep A

HAV antigen in faeces

detection of IgM anti-HAV

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Immunisation for Hep A?

Yes

Human normal Ig = short term protection

Vaccine - single dose = antibody for 1 year, booster = immunity for 10 years

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how many new hep B cases occur among people between ages 15-39

70%

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How much more infectious is Hep B than HIV

100 times

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Is there a vaccine available for Hep B

yes

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Is there a cure available for Hep B

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What type of virus is Hep B

partially double stranded DNA virus

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What family of viruses does Hep B belong to

hepadnavirus

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How many subtypes of Hep B exsist

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What is a dane particle

the intact virus (viral coat + DNA genome)

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What are the important antigens to know on Hep B

Hepatitis B surface antigen (HBs Ag)

- Hepatitis Be antigen (HBe Ag)

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If someone is hepatitis Be antigen positive what does this mean?

they have a very high viral load (very infectious)

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What’s the geographical distribution of Hep B like?

mainly high in developing countries, lower prevalence in developed countries

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How is HBV transmitted?

Bloodborne
Sexual
Perinatal (mother to child)

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Why is perinatal transmission such a problem in endemic areas?

if contract as a child you are then a carrier so can pass to others and can lead to long term liver problems (cirrhosis and liver cancer)

(80-95% chronicity in endemic areas compared to 5% chronicity in non-endemic areas)

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How is risk of chronic HBV infection affected by age of acquisition and immune status

neo nates 90-100%
children 20-40%
HIV positive 21%
adults <5%

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What are the possible outcomes of exposure to Hep B virus

Infection (65% subclinical)

death (1%)
persistent infection (HBs Ag > 6 months) (5-9%)
Recovery with immunity (90-95%)

In this country, small number die, some become carriers (variet of things can happen after that), but most will recover

What are the serological differences between someone who recovers from HepB and someone who develops a chronic infection

Recovery
once anti-HBe starts to form you are much less infective (about 3.5 months after exposure)

Chronic carriage
no antibodies developed to either HBs Ag or HBe Ag = risky patients

How is passive immunity achieved with Hep B? When is it used?

Hep B Ig from pooled plasma

single acute exposure in non-immune individual (administer within 48hrs)

also used for non-responders to active vaccine following a sharps exposure

how immunogenic is the HBV vaccine

highly immunogenic

is a booster required, if so when? of the HBV vaccine

not required for responders of the HBV vaccine

how is active immunity achieved for HepB

Hep B surface antigen (HBsAg) adsorbed on aluminium hydroxide adjuvant, produced by recombinant DNA technology

What is the protection like of active immunity vaccine for Hep B

good protection

What is the response like of active immunity vaccine for Hep B

response not always good so need to check antibody levels

How is the active Hep B vaccine administered

intramuscular

how many doses of the Hep B active vaccine do you need? when?

3 doses time zero, one month, 6 months

what is it important to do post immunisation of active HepB vaccine

test for antibody response 2-4 months after vaccination course complete

what post exposure prophylaxis is required for Hep B

none for responders Hep B Ig for non-responders (70-75% protection from infection)

What is the goal for treatment of chronic HBV infection

sustained viral suppression

What agents are avaliable to treat chronic HBV infections

- immunomodulatory agents (IFN-alpha) - nucleoside analogues (Iamivudine, telbivudine, entecavir) - nucleotide analogues (adefovir and entecavir, these don't cure but can really reduce viral load)

What type of virus is Hep C

flavivirus

How many genotypes of Hep C are there

Is there a vaccine avaliable for Hep C

How many genotypes of Hep B are there

What does a Hep C virus look like

Enveloped RNA virus

How is Hep C transmitted?

- IV drug use - blood and blood products - organ/tissue transplantation - sexual transmission - vertical transmission - occupational transmission - saliva?

How can we diagnose HCV

1. Anti-HCV test (detects presence of antibodies, indicates exposure to HCV) 2. HCV -RNA test (identifies presence of virus in blood, indicates active infection) 3. Viral load/quantitative HCV test (measures the number of viral particles in peripheral blood) 4. viral genotyping (determines type of HCV present)

How does and acute infection with recovery compare to a acute infection which progresses to chronic serologically

acute with recovery HCV RNA not present in recovery 'ALT' not present in recovery Anti HCV present acute with chronic HCV RNA present ALT present Anti-HCV present

incubation period of HCV

6-12 weeks

Describe the clinical course of HCV

Incubation 6-12 weeks Acute infection - Clinically mild, commonaly subclinical - Jaundice in 25% of patients Chronic Hep C - high frequency: at least 60% - mostly preceded by clinically inapparent infection - slowly progressive over 20+ years - progression from mild hepatitis to cirrhosis - link to liver cancer

What is the treatment of chronic Hep C

IFN alpha + ribavirin (+ boceprevir/ telaprevir for genotype 1) also 2nd gen protease inhibitors (much better as stops production of new viral particles) e.g. sofosbuvir

what recent advances have been made for hep C

might be able to potentially cure soon

What other virus does the Hep B vaccine protect against? | Why?

Hep D it's an RNA defective virus, can only replicate when HepB is there too Because relies on HepB producing it's protein coat. It can be independently transmitted just cant cause an infection

what is a 'super infection'? why is it important

i think when you are infected by Hep B and Hep D? huge reduction in recovery rate between a co-infection (90-95%) and a super infection (5-10%)

which virus is Hep E quite like? what is the main difference?

Hep A mortality with pregnancy