Hepatitis B

 Hepatitis B is a chronic liver infection, caused by the hepatitis B virus. This is prevalent in Asia and the Eastern Mediterranean region as in West Africa and the South Pacific but can be found in Europe and the Americas, too. It has been markedly decreased since vaccination was introduced thirty years ago but not all areas of the world are evenly vaccinated.

Hepatitis B can be transmitted with bodily fluids. Transfusion used to be a significant way but donor screening has been universal, especially in developed countries. It is easily transmitted sexually and with shared needles. A special form is mother-to-fetus transmission at the time of birth. There is mandatory testing and perinatal vaccination in the US and this form of transmission is exceedingly rare. Unfortunately, it is not so in many Asian countries.

Acute hepatitis B is mostly asymptomatic and is missed. Chronic disease is also rarely diagnosed because of symptoms but mostly on routine blood tests.

There are different phases of chronic hepatitis B, ranging from decades long immune tolerance, when the virus replicates but the body does not attack the infected liver cells (hence no hepatitis) to different immune active and inactive (carrier) phases. Infection may resolve spontaneously, more so in Caucasian than Asian patients.

In contrast to hepatitis C, the genetic material of the hepatitis B virus can be integrated into the liver cell’s DNA and this can cause liver cancer, even in patients, whose disease resolved, albeit to a much lesser extent.

 

Hepatitis B may also cause disease outside of the liver, the so-called extrahepatic manifestations: kidney disease, polyarteritis nodosa and aplastic anemia.

 

Vaccination is the most important way to fight hepatitis B. The newer, recombinant vaccines are well tolerated and very effective. In many places, vaccination is mandatory before age 14 and this strategy has been remarkably effective.

Treatment is effective mostly in suppressing the virus but is not curative in many patients. There are several oral medications, which are safe and effective and have been shown to prevent progression of the disease, stabilize even advanced disease and reduce the recurrence of liver cancer after its eradication by other means. They can also reduce the rate of transmission from mother to fetus and are used safely during pregnancy. These medications are used for very long times, frequently indefinitely. Interferon, an injectable drug, is used for about a year, alone or in combination with oral antivirals, but is also rarely curative and has many more side effects.

New therapeutics are being actively researched, aimed not only at viral suppression but also at elimination of the disease, by priming the body’s own immune cells to preferentially attack infected liver cells.