Hepatitis B – HBV – Symptoms and Treatment

Hepatitis B

Hepatitis B is a disease caused by HBV Hepatitis B virus which infects the liver of hominoidae, including humans, and causes an inflammation called hepatitis. Originally known as “serum hepatitis”, the disease has caused epidemics in parts of Asia and Africa, and it is endemic in China. About a third of the world’s population, more than 2 billion people, have been infected with the Hepatitis B virus. This includes 350 million chronic carriers of the virus. Transmission of Hepatitis B virus results from exposure to infectious blood or body fluids containing blood.

The acute illness causes liver inflammation, vomiting, jaundice and—rarely—death. Chronic Hepatitis B may eventually cause liver cirrhosis and liver cancer—a fatal disease with very poor response to current chemotherapy. The infection is preventable by vaccination.

Hepatitis B virus is an hepaDNAvirus—hepa from hepatotrophic and DNA because it is a DNA virus – and it has a circular genome composed of partially double-stranded DNA. The viruses replicate through an RNA intermediate form by reverse transcription, and in this respect they are similar to retroviruses. Although replication takes place in the liver, the virus spreads to the blood where virus-specific proteins and their corresponding antibodies are found in infected people. Blood tests for these proteins and antibodies are used to diagnose the infection.

Symptoms

Jaundice in a man with hepatic failure.

Acute infection with Hepatitis B virus is associated with acute viral hepatitis – an illness that begins with general ill-health, loss of appetite, nausea, vomiting, body aches, mild fever, dark urine, and then progresses to development of jaundice. It has been noted that itchy skin has been an indication as a possible symptom of all hepatitis virus types. The illness lasts for a few weeks and then gradually improves in most affected people. A few patients may have more severe liver disease (fulminant hepatic failure), and may die as a result of it. The infection may be entirely asymptomatic and may go unrecognized.

Chronic infection with Hepatitis B virus may be either asymptomatic or may be associated with a chronic inflammation of the liver (chronic hepatitis), leading to cirrhosis over a period of several years. This type of infection dramatically increases the incidence of hepatocellular carcinoma (liver cancer). Chronic carriers are encouraged to avoid consuming alcohol as it increases their risk for cirrhosis and liver cancer. Hepatitis B virus has been linked to the development of Membranous glomerulonephritis (MGN).

Treatment

Acute Hepatitis B infection does not usually require treatment because most adults clear the infection spontaneously. Early antiviral treatment may only be required in fewer than 1% of patients, whose infection takes a very aggressive course (“fulminant hepatitis”) or who are immunocompromised. On the other hand, treatment of chronic infection may be necessary to reduce the risk of cirrhosis and liver cancer. Chronically infected individuals with persistently elevated serum alanine aminotransferase, a marker of liver damage, and HBV DNA levels are candidates for therapy.

Although none of the available drugs can clear the infection, they can stop the virus from replicating, and minimize liver damage such as cirrhosis and liver cancer. Currently, there are seven medications licensed for treatment of Hepatitis B infection in the United States. These include antiviral drugs lamivudine (Epivir), adefovir (Hepsera), tenofovir (Viread), telbivudine (Tyzeka) and entecavir (Baraclude) and the two immune system modulators interferon alpha-2a and pegylated interferon alfa-2a (Pegasys). The use of interferon, which requires injections daily or thrice weekly, has been supplanted by long-acting pegylated interferon, which is injected only once weekly. However, some individuals are much more likely to respond than others and this might be because of the genotype of the infecting virus or the patient’s heredity. The treatment works by reducing the viral load, (the amount of virus particles as measured in the blood), which in turn reduces viral replication in the liver.

Infants born to mothers known to carry Hepatitis B can be treated with antibodies to the Hepatitis B virus (Hepatitis B immune globulin or HBIg). When given with the vaccine within twelve hours of birth, the risk of acquiring Hepatitis B is reduced 95%. This treatment allows a mother to safely breastfeed her child.

Reactivation

Hepatitis B virus DNA persists in the body after infection and in some people the disease recurs. Although rare, reactivation is seen most often in people with impaired immunity.

Hepatitis B goes through cycles of replication and non-replication. Approximately 50% of patients experience acute reactivation. Male patients with baseline ALT of 200 UL/L are three times more likely to develop a reactivation than patients with lower levels. Patients who undergo chemotherapy are at risk for HBV reactivation. The current view are that immunosuppressive drugs favor increased HBV replication while inhibiting cytotoxic T cell function in the liver.

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