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Characteristic of Hepatitis B virus

Dr.Jitender Kumar

Department of Biotechnology

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Historical aspects

  • Jaundice described by Hippocrates in 5th century BC.
  • Jaundice reported among recipients of human serum and yellow fever vaccines in 1930s and 1940s.
  • Australian antigen described in 1965.
  • Serologic based tests developed in 1970s.

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Features Hepatitis B Virus

  • Hepadnaviridae family (DNA)
  • Numerous antigenic components
  • Humans are only known host
  • May retain infectivity for at least 1 month at room temperature

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  • Reported 200 million carriers worldwide
  • Established cause of chronic hepatitis and cirrhosis
  • Human carcinogen - cause of up to 80% of hepatocellular carcinomas

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Hepatitis B Virus Infection

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HBsAg

HBcAg

HBeAg

Hepatitis B Virus

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Serological features

  • Incubation period varies from 6 weeks to 6 months (average 120 days)
  • Nonspecific symptoms of fever, malaise, headache, myalgia
  • Illness not specific for hepatitis B
  • At least 50% of infections asymptomatic

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Hepatitis B pathogenecity

  • Chronic hepatitis
  • Hospitalization
  • Cirrhosis
  • Hepatocellular carcinoma
  • Death

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Chronic Hepatitis B Virus Infection

  • Chronic viremia
  • Responsible for most mortality�
  • Overall risk 10%�
  • Higher risk with early infection�

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Risk of Chronic HBV Carriage by Age of Infection

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Hepatitis B Transmission

  • Reservoir Human Endemic�
  • Transmission Bloodborne

Subclinical cases

transmit �

  • Communicability 1-2 months before

and after onset of

symptoms

Chronic carriers

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Hepatitis B Transmission

  • If mother positive for HBsAg and HBeAg
    • 70%-90% of infants infected
    • 90% of infected infants become chronic carriers

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  • If positive for HBsAg only
    • 20% of infants infected
    • 90% of infected infants become chronic carriers

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  • High (>8%): 45% of global population
    • lifetime risk of infection >60%
    • early childhood infections common

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  • Intermediate (2%-7%): 43% of global population
    • lifetime risk of infection 20%-60%
    • infections occur in all age groups

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  • Low (<2%): 12% of global population
    • lifetime risk of infection <20%
    • most infections occur in adult risk groups

Global Scenario of HBV Infection

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Hepatitis B – United States, 1978-2000

Hepatitis B vaccine licensed

Decline among

homosexual men

Decline among

IV drug users

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  • Total infections 80,000/yr
  • Current carriers >1 million
  • New carriers >5,000
  • Death
    • fulminant hepatitis 200
    • liver cancer 1,500
    • cirrhosis 4,000

HBV Disease in States

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Age of Infection of Acute and Chronic Hepatitis B Virus Infection

Acute infection

Chronic infection

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Risk Factors for Hepatitis B

CDC Sentinel Sites. 1992-1993 data.

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Hepatitis B Virus Infection by Duration of High Risk Behavior

0

3

6

9

12

15

Years at Risk

0

20

40

60

80

100

Percent infected

IV drug user

Homosexual men

HCWs

Heterosexual

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Strategy to Eliminate Hepatitis B Virus Transmission

  • Prevent perinatal HBV transmission
  • Routine vaccination of all infants
  • Vaccination of children in high-risk groups
  • Vaccination of adolescents
  • Vaccination of adults in high-risk groups

�

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REFERENCES

1.GENERAL MICROBIOLOGY BY STANIER

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  • THANKS