Hepatitis-B

 

 

 

Microbiology

Outmoded designation: serum hepatitis, due to its historically recognized route of percutaneous transmission (interesting to note that most of the patients with "serum hepatitis" were not actually infected with HBV)
Partially double-stranded DNA virus member of the hepadnavirus family (hepatotropic DNA viruses)
Reverse-transcriptase activity associated with the viral DNA
HBSag
product of the S gene of HBV
major surface protein
several subtypes
anti-HBs is the protective antibody
extremely large production during an infection (500µg/ml or 10 trillions particles per ml)
HBcAg
core antigen
product of the C gene
HBeAg
soluble nucleocapsid protein
reliable marker of replication and infectivity

Epidemiology

Virus found in every body fluid of infected individuals (saliva, tears, CSF, seminal fluid, ascites, breast milk, gastric fluid, synovial fluid, pleural fluid, urine and even (rarely) feces)
Low infectivity with oral ingestion of the agent
Sexual and perinatal transmission are important routes
Carrier state in human (more than 200 millions in the world) is the main reservoir
Prevalence is 0.1 and 0.5% in normal population but as high as 20% in some high risk groups
Higher risk groups: 
Down's syndrome
leprosy
leukemia
Hodgkin's
polyarteritis
IVDU 
hemodialysis patients
spouse of acutely infected persons
sexually promiscuous people
people who required repeated transfusions (low risk with present-day blood products with screening

Clinical syndromes

Subclinical
Fulminant acute hepatitis
Chronic persistent hepatitis
Chronic active hepatitis
Hepatocellular carcinoma

Diagnosis

Serology

Comments on treatment

Acute: no therapy recommended
Chronic
recommended: interferon-alfa (2a or 2b) (4-6 months of treatment. 33% will respond)
alternative: lamivudine (duration not established)
Prevention (after transplantation for HBV-induced cirrhosis