Incidence	- fairly common worldwide
Age
Sex	- M = F
Geography	- worldwide; low carrier rate (0.5%) in UK and USA, high rate (10-15%) in parts of Africa, the Middle East and the Far east
Aetiology	- DNA-genome hepadnavirus - nuclocapsid of core protein (HBcAg) surrounded by outer envelope (HBsAg) - several subtypes of HBsAg proteins - can be used in epidemiology - incompletely double-stranded DNA genome + DNA polymerase/reverse transcriptase - HBeAg - forms by self-cleavage of pre-core/core gene product - replication takes place in endoplasmic reticulum - not directly cytopathic - cellular immune response destroys the liver - specific failure of T cells to recognise HBV antigens leads to viral persistence - HBV mutants can emerge in long term carriers or be acquired by infection; these lack e-antigen; hence serum markers may be poor indicators of infectivity and HBV DNA must be measured Spread - blood contact: transfusions, IVDU, tattoo needles - close personal contact: especially sexual contact, especially in male homosexuals - vertical transmission during parturition/soon after birth is most common route of spread worldwide - ? insect vectors
Presentation	History - long incubation: 1-5 months - infection is subclinical in many cases - viraemia -> nonspecific symptoms - nausea, anorexia, distaste for cigarettes - in some patients, there is a serum sickness-like immunological syndrome with urticaria or a maculopapular rash and polyarthritis affecting small joints in the prodromal phase - fever - some patients become jaundiced - dark urine and pale stools
Investigations	LFTs - prodromal phase: - serum bilirubin normal; bilirubinuria and increased urinary urobilinogen - raised AST/ALT precede jaundice - icteric phase: - raised serum bilirubin - AST reaches maximum at 1-2 days after appearance of jaundice - up to 500 IU/L - ALP usually < 300 IU/L - post-icteric: - AST/ALT may be raised for weeks-months Haematological tests - leucopenia - relative lymphocytosis - prolonged PTT in severe cases - raised ESR
Macro
Micro
Staging
Serum markers	Viral markers - HBsAg - acute or chronic infection - HBeAg - acute hepatitis B; persistent in continued infectious state, chronicity, increased severity of disease - HBV DNA - implies viral replication; found in serum and liver - Anti-HBs - immunity to HBV; previous exposure - Anti-HBe - seroconversion - Anti-HBc IgM - high titre in acute HBV, low titre in chronic HBV - Anti-HBc IgG - past exposure to HBV
Management	- no specific management - symptomatic Prevention and prophylaxis - avoid risk factors e.g. needle sharing, male homosexual partners, prostitutes - patients with e antigen and HBV DNA in their blood are the most infectious - counselling - avoid blood and blood products in developing world - active immunization to high-risk groups - combined passive and active prophylaxis given to medical staff with accidental needlestick injury, all newborn babies of HBsAg-positive mothers, regular sexual partners of HBsAg-positive patients, who have been found to be HBV-negative
Prognosis	Course - most patients recover completely - fulminant hepatitis occurs in 1% - 5-10% will become chronic asymptomatic carriers; amongst these, there is an annual clearance rate of 1-2% (HBsAg +ve, HBeAg -ve, HBe Ab +ve, HBV DNA -ve) - some develop chronic hepatitis and HCC - commonly have e antigen and HBV DNA present in serum - course depends on host immunocompetence and genetic factors, and on virulence of virus
Complications

Hepatobiliary medicine

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