Viral Hep B in Asia Backgrounder

What is Viral Hepatitis B?

Viral hepatitis B, the most common serious liver infection in the world, is a major global public health problem.

The hepatitis B virus is a small DNA virus that belongs to the Hepadnaviridae family of viruses. It is one of the most serious types of viral hepatitis. It infects the liver and can cause both acute and chronic, lifelong infection which in years later, the patient may develop cirrhosis (scarring) of the liver, liver cancer, liver failure, and even death.

Hepatitis B virus infection is the 10th leading cause of death worldwide. There are 1.2 million deaths per year caused by chronic hepatitis, cirrhosis, and hepatocellular carcinoma. The prevalence of chronic hepatitis B virus infection is high (>8%) in all socioeconomic groups in Southeast Asia, including China, Korea, Indonesia, and the Philippines.

Symptoms

Chronic hepatitis B can be described as a "silent infection" because most people do not have noticeable symptoms when they are infected. In fact, chronic hepatitis B causes no symptoms in about 69% of the infected people. They unknowingly may pass the virus to others.

In acute hepatitis B, an incubation period of anywhere from two to six months, before symptoms occur in approximately 30% of infected individuals. These symptoms are not specific to hepatitis and are often mistaken for those of influenza - fever, fatigue, joint or muscle pain, loss of appetite, nausea, and vomiting. Jaundice (yellow discoloration of eyes and skin), which is usually a sign of liver damage, may not occur.

Transmission

Hepatitis B virus is up to 100 times more infectious than the AIDS virus. It is most frequently transmitted from the mother to her newborn in endemic regions such as Asia. Early infection in newborn and infancy has no symptoms and has over 90% chance of infection progressing to chronic infection. The other main ways of getting infected with hepatitis B virus are through blood or body fluid contact.

In many developing countries, most children become infected with the virus from infected mother at birth or from child-to-child contact in household settings. Reuse of non-sterilized needles and syringes in poor healthcare facilities is also an important and preventable factor.

Spread within households from sharing toothbrushes or razors may also occur because hepatitis B virus can survive for at least seven days outside the body. Viral hepatitis B virus is a major infectious occupational hazard of health workers.

Hepatitis B virus is not transmitted casually. It cannot be spread through air, food, water, breast-feeding, kissing, hugging, coughing, sneezing, or sharing eating utensils or drinking glasses. It cannot be spread through casual contact in the workplace.

Diagnosis and Monitoring of Chronic Hepatitis B

A simple blood test can diagnose a viral hepatitis B infection. A patient with an acute infection will test positive for the hepatitis B virus (HBsAg), HBc-IgM, and possibly the HBe-antigen (HBeAg). If these tests remain positive on repeat testing six-month later, recovery is unlikely and chronic infection is established.2 These chronically infected individuals, often called “carriers”, are infectious for life, although they may not experience symptoms themselves. Approximately 90% of babies exposed to hepatitis B virus under the age of one year will go on to become chronically infected, compared with only 5% of adults.

It is vitally important that all patients with chronic hepatitis B are monitored regularly or referred to a liver specialist for assessment and early detection of disease progression. Appropriate therapy can reduce the risk for developing cirrhosis and/or liver cancer.

Screening and vaccination of close family / household members and sexual partners is recommended.

Treatment

The goal of treatment for chronic hepatitis B is to clear the virus or to suppress it permanently, thus preventing inflammation and scarring of the liver, or the progression of the disease. New oral antiviral treatments can achieve viral suppression by preventing the virus from replicating. In rare cases, these oral antiviral treatments can clear the body of viral hepatitis B. The immune system of the infected person can be boosted by interferon and together with its antiviral function, can also achieve viral clearance or control.

Those with chronic hepatitis B are monitored regularly during therapy in order to evaluate the success of the treatment on the virus. It is essential that people taking antiviral treatment do continue with treatment as instructed by the doctor to get the best benefit from therapy progression.

Prevention

Viral hepatitis B infection is preventable. A safe and effective viral hepatitis B vaccine has been available since 1982 and has been given to more than 500 million people around the world. Although the vaccine will not cure chronic hepatitis, it is 95% effective in preventing infections from developing, and is the mainstay for hepatitis B virus prevention in endemic Asian regions where universal vaccination as part of the infant immunisation schedule has been promulgated by WHO since 1991. It is the first vaccine effective against a major human cancer.