اعداد / يوسف عبدالله الشمراني اشراف / د 0 هشام ابو عوده

Hepatitis B virus :

Epidemiology : The hepatitis B virus is present world – wide with an estimated 300 million carriers. The UK and the USA have a low carrier rate (0.5%), but it rises to % in parts of Africa, the Middle and the Far East.

Geographic distribuion :

Hepatitis B by age group

Hepatitis B by races :

Transmission : Spread of this virus is either by the intravenous route (e.g. by transfusion of infected blood or blood products, or by contaminated needles used by drug addicts, tattooists or acupuncturists ), or by close personal contact, such as during sexual intercourse, particularly in male homosexuals. The virus can be found in semen and saliva. Vertical transmission from mother to child during parturition or soon after birth is the usual means of transmission world – wide. There is no evidence that HBV replicates in insect vectors but the virus has been detected in mosquitoes and bed bugs.

Pathogenesis : host immune responses are more important than virologic factors in the pathogenesis of liver injury Host cellular and humoral immune responses are linked to T lymphocytes, which enhance viral clearance from hepatocytes and cause liver injury.

Dignosis : The presence of HBsAg in serum is diagnostic for HBV INFECTION. IN 5% TO 10% of acute case in which the HBsAg levels fall below sensitivity thresholds of current assays. The presence of of IgM anti-HBc in serum confirm the a recent acute hepatitis B infection. Another highly reliable marker of active HBV replication and diagnosis is the presence of HBV DNA in serum, detectable early during the course of acute HBV infection.

Serology :

Signs and symptoms : Initial symptoms included a recent history of nausea, vomiting, anorexia, scleral icterus, jaundice, rashes, (e.g. urticaria or a maculopapular rash) and polyarthritis affecting small joints occurring in up to 25% of cases in the prodromal period. Fever is usual.

Course : The majority of patients recover completely, fulminant hepatitis occurring in up to 1%. Some patients go on to develop chronic hepatitis and hepatocellular carcinoma or become asymptomatic carries.

Factors affecting outcome : The outcome depends upon several factors, including the virulence of the viruses and the immunocompetence and age of the patient as well as some genetic factors, while abnormalities in mannan- binding protein may alter host defence to HBV.

Prevention : Comprehensive strategies should be implemented to prevent and maintain protection against HBV infection and should be widely available to eliminate transmission that occurs during infancy and childhood as well as during adolescence and adulthood. Thus, alteration in sexual behavior, screening of high-risk patients and blood products, developing needle exchange programs, and cultural outreach and education may impact HBV transmission.

Goals of prevention : The goals should be to identify person who require immunoprophylaxis for the prevention of infection and provide long-term protection through vaccination to decrease the risk of chronic HBV infection and its subsequent complications, as well as minimizing adverse effects and cost of therapy.

PREPARED BY / YOUSEF ALSHOMRANI