Introduction

Hepatitis B is an infection in the liver, caused by the hepatitis B virus (HBV). It is the most common cause of hepatitis. It is endemic in Asia and the Far East (up to 10% have chronic hepatitis B), but rare in the developed world.

Spread occurs via infected blood – e.g. via sexual intercourse, vertical transmission from mother to baby, and historically it was also seen in blood transfusions.

The incubation period is between 6-23 weeks.

The serologically important factors, which help it determining immunisation status as well as disease status include:

  • Surface antigen – HBsAg
  • Core antigen – HBcAg
  • e antigen – HBeAg

Epidemiology and Aetiology

  • Major health problem – 300 million carriers
  • Incubation 1 – 4 mths
  • Parenteral transmission – sexual, IV, perinatal
  • 0.5% of UK population are carriers, but this is as much as 10-15% in some countries in the developing world. in some far eastern countries, 1/3 of people are carriers
  • In UK, 1 in 350 have chronic hepatitis B infection
  • In recent years, rates have declined amongst younger populations due to vaccination
  • Risk factors
    • IV drug use
    • Multiple sexual partners
    • Occupational exposure – e.g. healthcare workers
    • Close family or contact who is infected or a carrier
    • Receiving regular blood products
    • Travel to high risk areas
    • Children born to mothers who are carriers or infected
    • Prison inmates
    • In the UK most cases are due to sexual exposure or IV drug use

Presentation

May be asymptomatic, or have minor flu-like symptoms. Symptomatic individuals may present with:

  • Fever
  • Malaise
  • Faitgue
  • Joint pains
  • Urticaria
  • Pale stools / dark urine / jaundice

Acute Hepatitis B

  • Incubation period 6 weeks – 6 months
  • 1% of patients will develop liver failure
  • 90% will recover
  • 10% will go on to develop chronic hepatitis B infection
  • Jaundice, malaise, abdominal pain, nausea & fever – 1 to 3 months
  • 70% anicteric (not jaundiced)

Maternal transmission is different

  • 90% of newborns born to infected mothers will have chronic hepatitis B infection
  • Up to 25% will have chronic complications. Including:
    • Cirrhosis
    • Hepatocellular carcinoma

Diagnosis

  • Derranged LFTs
    • ↑bilirubin
    • ↑ALT / AST
    • ↑ALP
  • Positive HBsAg
    • Present in blood for 1-6 months post exposure
    • If present after 6 months then this is diagnostic for carrier status
  • HBeAg
    • Present from 6 weeks to 3 months after exposure
    • Indicates period of high infectivity
    • May or may not be present in chronic disease
  • Anti-HBs
    • Antibodies to surface antigen
    • Appear 10 months after infection
    • Imply immunity
    • Also seen in previous vaccinated individuals

Understanding Hepatitis B testing

There are several antigens and antibodies that are present during, and following Hepatitis B infection. Understanding which of these is present and when can help you identify if a persen has a current or past infection, and their immunity status.

Clinical StatusSerological Markers
Immunity following previous natural exposureAnti-HBc (may be negative if infection was a long time ago)
Anti-HBs
Previously VaccinatedAnti-HBs
Acute InfectionHBs-Antigen
Anti-HBc
HBV-DNA
HBe-Antigen (may be negative depending on timing)
Chronic InfectionHBs-Antigen – HBsAg present 6 months after exposure is diagnostic for chronic infection
Anti-HBc
HBV-DNA
(all above still positive 6 months after diagnosis)

Pathology

In chronic disease, viral DNA may become incorporated into host DNA. HbsAg is present on the surface of infected hepatocytes, and this causes T cells to induce apoptosis in these cells. The pathogenesis is different to that of HAV (Hepatitis A Virus) , where the apoptosis is not induced by the immune system, but by the infected cell itself – thus HAV does not have the ability to cause chronic disease.

Complications

  • Acute liver failure rare – 0.1 to 0.5%
  • Chronic Hepatitis B is specified as viraemia at 6 months after initial diagnosis/sympotms
    • Occurs in about 10% of adult infection, and 90% of vertical transmission cases
    • Chronic disease can be divided into e-antigen positive and e-antigen negative
    • E-antigen positive disease is associated with higher viral replication, and therefore higher risks of infectivity
    • Chronic infection benign in the majority of patients – especially in non-drinks with normal liver function
    • Chronic infection depends on age of initial infection:
    • 90% of people who get the disease in vertical transmission (i.e. from their mum) will develop chronic disease
    • 5-10% of adults who contract hepatitis B will develop chronic disease
    • 30% of people with chronic infection will get cirrhosis
    • In chronic HBV 40% men and 15% women die from liver failure
  • Cirrhosis
    • HIV and HepC infection increase the likelihood of cirrhosis
  • Hepatocellular carcinoma

Management

If acutely unwell – will need hospital admission. Otherwise can be managed in primary care, with non-urgent referral to gastroenterologist or infectious diseases specialist upon confirmation of diagnosis.

Symptomatic management is often all that is required in the acute phase. Itching due to jaundice may be difficult to manage.

It is important to check for other commonly associated infections, including HepC and HIV.

  • 10% of patients with HIV will also be infected with HBV
  • Liver complications are more common in those with co-infection with HIV. However, conversely, HBV is not thought to affect HIV disease progression.

If not already done, ensure diagnosis is confirmed with serological testing, and FBC and Lots are performed.

  • Antiviral therapy – only for selected patients with chronic infection – requires specialist input
    • Lamivudine
    • Entecavir
    • Tenofovir (adefovir)
    • Interferon
    • Variable success rates
  • The aim of treatment is to reduce the risk of complications. Therefore patients who already have cirrhosis are likely not to benefit. Other factors when deciding who to treat include:
    • HBe-antigen status
    • Elevated Transaminase
    • HBV DNA levels
    • Not cirrhotic
  • Prevented by vaccination
  • Lifestyle advice
    • Counsel about the diagnosis and the course of the disease, including advise not to donate blood and the route of transmission
    • Advise alcohol abstinence
    • Safe sex advice
    • Advise partners become vaccinated, and to avoid sexual contact (including oral sex) until vaccination is complete

Reducing transmission

Vertical transmission

To babies of infected mothers:

  • Give HBIG within 24 hours of birth
  • Give full course of vaccination
  • These two can be given simultaneously (at different sites)
  • This reduces vertical transmission by 90%

Intimate contacts

  • Contact tracing may be required
    • This can be difficult in chronic infection
  • Infectious period is from 2 weeks before jaundice, until HBsAg negative serology
  • HBIG can be given to contacts after a single exposure (e.g. sexual contact or needle stick) – should be given as soon as possible (most effective in first 48 hours) but can be given up to a week after exposure

Prognosis

  • 80% of patients will have full recovery
  • 10% develop chronic hepatitis
    • Associated with cirrhosis and liver carcinoma
    • Risk of cirrhosis is 10-20% without antivirals
    • Once cirrhosis has developed, there is a high risk of culminant liver failure
    • 5-year survival in decompensated cirrhosis is 15%
  • 10% go on to be “carriers”

References

  • Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Hepatitis B - patient.info

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