Hepatitis B virus

Hepatitis B virus

Hepatitis B causesd through hepatitis B virus. It is an enveloped DNA virus.

It causes serious liver infection.

Hepatitis B is vaccine preventable disease.

Hepatitis B have oncogenic property, cause hepatocellular carcinoma.

Morphology

When examined under electron microscope, hepatitis B shows three types of particles;

1. Spherical particles

Hepatitis B Surface antigen HBsAg.

Hepatitis B has three types of surface antigen;

Viral DNA

HBsAg

HBcAg; core antigen 

ABeAg; nucleocapsid protein 

2. Tubular particles

3. Double walled spherical 

Double wall spherical particles

Source and Mode of Transmission

It is blood borne virus.

Infection is transmitted by;

1. Parenteral routes

2. Sexual transmission 

3. Blood, semen and saliva act as hepatitis B carrier.

4. Hepatitis B virus commonly spread by exposure of infected;

Infected blood and blood products 

Infected body fluids

Semen

Vaginal secretion

Breast milk

Risk to babies is high if mother is ABeAg +ve 60-90%

Congenital transmission is quite common for carrier mother.

Infection is usually acquired during birth by contact material blood or birth canal.

Contaminated needle during medical surgical or dental practices.

Pathogenesis and Clinical Significance

Hepatitis B is also known as serum Hepatitis.

Hepatitis B disease two stage;

1. Prejaundice

Loss of appetite

Fatigue

Fever

Malaise

Abdominal discomfort 

Cause chronic Hepatitis, liver cirrhosis and primary hepatic cancer.

2. Appearance of jaundice 

With appearance jaundice patient feel better, but liver remains tender.

ABsAg appear in blood during incubation period, 2-6 months.

Laboratory Diagnosis

Specimen collection

Serum sample

Serological test; detected by ELISA

Detection of hepatitis B antigen and antibody 

Observation and Result

AntiABs; immunity due to vaccination.

ABsAg; show infection

ABeAg; show infectivity and chronic hepatitis.

Prophylaxis

Hepatitis B is most commonly transmitted blood borne virus may via contaminated instrument or accidental needle.

Administration of routine hepatitis B vaccination as standard precaution to prevent blood borne pathogen.

Avoid direct or indirect contact with blood, semen, body fluids.

Screening of blood, organ donors and pregnant women.

Proper disposable of biomedical waste.

Immunization

Both passive and active immunization.

Passive immunization; With HBIG (Hyperimmune hepatitis B immunoglobulin).

Active immunization; Vaccine is prepared by purifying 22nm particle of HBsAg from plasma of healthy carriers. 

The vaccine is immunogenic and safe. 

It is given IM into deltoid region in older and infants into anterolateral region of thigh.

Infected babies (born to carrier mother's) HBIG gives IM immediately after birth and followed by full course of vaccine.

Treatment

Acute hepatitis recovery occurs is about 99%

In chronic hepatitis B antiviral drug therapy is required.

For example; Lamivudine and Adefovir are quite effective.