Thursday, August 14, 2014

Hepatitis - a wide spread ticking time bomb

Compulsory HBV vaccination has been instituted in Malaysia since 1989. Nevertheless, hepatitis B remains an important cause of morbidity and mortality.

Chronic hepatitis B is a worldwide phenomenon, and it is estimated that there are more than 350 million hepatitis B virus (HBV) carriers in the world, with 75% of them living in the Asia Pacific region, where the majority of infections are acquired perinatally (period immediately before and after birth) or in early childhood.

Approximately one million people die from HBV-related liver disease every year. The implementation of effective vaccination programmes in many countries has resulted in a significant decrease in the incidence of acute hepatitis B.

Compulsory HBV vaccination has been instituted in Malaysia since 1989. Nevertheless, hepatitis B remains an important cause of morbidity and mortality, and many individuals who carry the virus (HBsAg-positive) remain undetected and unaware of the infection, and therefore, pose a danger to themselves and others close to them.

Patients with chronic hepatitis B seldom exhibit symptoms apart from fatigue, unless they have complications such as decompensated liver cirrhosis.

Physical examination may be completely normal. Those with end-stage liver disease may have jaundice, big spleen, ascites, leg swelling and encephalopathy.

Routine laboratory tests may be normal. There may be mild to moderate increase in liver enzymes (serum AST and ALT), which can increase dramatically and substantially in patients who develop exacerbations.

Doctors following up patients with apparent “silent” chronic hepatitis B will look for signs of progression to cirrhosis evidenced by hypersplenism (big spleen with decreased white blood cell and platelet counts) or impaired liver synthetic function, such as low serum albumin, prolonged prothrombin time and high serum bilirubin levels.

The natural course of chronic hepatitis B infection is determined by the interplay between virus replication and the host immune response.

Other factors that can influence the progression of HBV-related liver disease include gender, alcohol consumption and concomitant infection with other hepatitis viruses.

The outcome of chronic hepatitis B infection depends on how severe the liver disease is at the time HBV replication is suppressed.

Patients with this infection may be in an inactive carrier state, but can progress to cirrhosis, hepatic decompensation and liver cancer, which may prove fatal.

The prognosis is worse in HBV-infected patients from endemic areas like South-East Asia.

Twelve to 20% of patients with chronic hepatitis B may progress to cirrhosis; 20 to 23% of those with compensated cirrhosis can progress to hepatic decompensation; while 6 to 15% will progress to liver cancer within five years.

Patients with compensated cirrhosis have an 85% survival rate at five years, while those with decompensated cirrhosis have survival rates of 55 to 70% at one year and 14 to 35% at five years.

Presently, doctors may wish to know the viral genotype of their chronic hepatitis B patients. Traditionally, eight genotypes (A to H) have been identified, with genotypes B and C being more prevalent in East Asia and South-East Asia, where perinatal or vertical transmission plays an important role.

Genotype B patients are also associated with spontaneous seroconversion (HBeAg to antiHBe) at a younger age, have less active liver disease, and show slower progression to cirrhosis and less frequent liver cancer than genotype C.

Laboratory tests include a complete blood count, liver enzymes (AST, ALT), total bilirubin, alkaline phosphatase, albumin, prothrombin time and tests for HBV replication (HBeAg, anti-HBe, HBV DNA).


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