Hepatitis B Flashcards
What type of virus Hepatitis B is?
- double - strand DNA hepadnavirus
Modes of spread and incubation period of Hepatitis B
Spread via:
- exposure to infected blood or body fluids
- vertical transmission (from mother to child)
Incubation period: 6-20 weeks
Symptoms of hepatitis B
(acute and chronic)
Acute (50% symptomatic and 50% asymptomatic:
- jaundice
- fever
- elevated liver transaminases
- tiredness
- polyarthritis
- loss of appetite
Chronic Hepatitis B may be asymptomatic → screen people at risk
People at risk of Hepatitis B
- born in the areas of high or immediate Hep B risk (including immigrants and adopted children)
- household contacts of an infected person
- sexual contacts of an infected person
- IV drug users
- those with multiple sexual partners
- those with history of STDs
- homosexual men
- inmates or correctional facilities
- individuals with chronically elevated ALT/AST levels
- people infected with HIV or Hep C
- renal dialysis patients
- pregnant women
Is chronic Hep B common?
90% of people recover completely from an acute Hep B
10% develop chronic infection:
- 20% of these chronically infected develop cirrhosis
- 1% develop liver failure
The marker of chronic Hep B
HBsAg positive
> 6 months
The structure of the Hepatitis B virus
Factors that may influence the course of Hep B disease
Management of Hepatitis B
- pegylated interferon-alpha (1st line) used to be the only treatment available → reduces viral replication in up to 30% of chronic carriers
- other antiviral medications are increasingly used → to suppress viral replication
Examples: tenofovir, entecavir and telbivudine (a synthetic thymidine nucleoside analogue)
Factors that predict a good response to pegylated interferon-alpha treatment for Hep B
pegylated interferon-alpha → reduces viral replication in up to 30% of chronic carriers
A better response is predicted by
- being female
- < 50 years old
- low HBV DNA levels
- non-Asian
- HIV negative
- high degree of inflammation on liver biopsy
Who should be vaccinated against Hepatitis B?
- part of UK child vaccination schedule → at 2, 3 and 4 months of age
- at risk groups who should be vaccinated include: healthcare workers, intravenous drug users, sex workers, close family contacts of an individual with hepatitis B, individuals receiving blood transfusions regularly, chronic kidney disease patients who may soon require renal replacement therapy, prisoners, chronic liver disease patients
What is in the Hep B vaccine?
Recombinant yeast with HepBsAg plasmid inserted
Risk factors for failure of response to Hep B vaccine
- around 10-15% of adults fail to respond or respond poorly to 3 doses of the vaccine
- Risk factors include: age over 40 years, obesity, smoking, alcohol excess and immunosuppression
How many doses of Hep B vaccine are needed?
3 doses
*booster at 5 years
Testing for anti-HBs (after the vaccine):
- who should be tested
- testing for anti-HBs is only recommended for those at risk of occupational exposure (i.e. Healthcare workers) and patients with chronic kidney disease
- In these patients anti-HBs levels should be checked 1-4 months after primary immunisation
Testing for anti-HBs (after the vaccine):
- interpretation of anti-HbS levels
