Exposure to HBV can produce a variety of different states (the percentages quoted are for adults):
- 60-65% show subclinical disease and recover fully i.e. no resultant liver damage
- 20-25% develop acute hepatitis:
- 99% of patients recover
- 1% develop fulminant hepatitis - with a case mortality of about 80%
- 5-10% become "healthy" carriers i.e. HBsAg +ve after 6 months - less than 5% show changes on liver biopsy that range from non-specific minimal abnormalities to chronic active hepatitis and cirrhosis. Infectivity and ongoing disease is indicated by a positive serum HBV DNA, IgM anti-HBc and HBeAg
- 5-10% develop chronic hepatitis - which may be:
- chronic persistent
- chronic active - which may progress to cirrhosis and hepatocellular carcinoma
The likelihood of chronic disease following HBV exposure is more likely in:
- males than females - a 6 fold increased risk
- in those with immunological incompetence, such as:
- the very young and the very old - more than 90% of exposed neonates develop chronic disease
- homosexuals
- AIDS sufferers
- patients with underlying malignancy e.g. leukaemia
- patients on immunosuppressive therapy
The risk of hepatocellular carcinoma is increased 10-390 fold in patients with chronic HBV disease.
Concomitant infection with hepatitis D virus is generally associated with a poorer prognosis than infection with HBV alone.
Reference:
- Pulse 2002; 62(31):8.
- Prescriber 2005; 16(6):66-75.
- Wright, TL et al.. Clinical aspects of hepatitis B virus infection. Lancet 1993; 342: 1340-45.