Hepatitis B is a disease caused by hepatitisB virus (HBV) which infects the liver of hominoidae, including humans, and causes an inflammationcalled hepatitis.Originally known as "serum hepatitis", the disease has caused epidemics inparts of Asia and Africa, and it is endemic in China. About a third of the world'spopulation, more than 2 billion people have been infected with thehepatitis B virus. This includes 350 million chronic carriers of the virus.Transmission of hepatitis B virus results from exposure to infectious blood orbody fluids containing blood.
The acute illness causes liver inflammation, vomiting, jaundice andrarely death. Chronic hepatitis B may eventually cause liver cirrhosis andliver cancera fatal disease with very poor response to current chemotherapy. The infectionis preventable by vaccination.
Hepatitis B virus is a hepadna virus.Hepafrom hepatotrophic and dna because it is a DNA virus andit has a circular genomecomposed of partially double-stranded DNA. The viruses replicate through an RNA intermediate form byreverse transcription, and in this respect they are similar to retroviruses.Although replication takes place in the liver, the virus spreads to the bloodwhere virus specific proteins and their corresponding antibodies arefound in infected people. Blood tests for these proteins and antibodies areused to diagnose the infection.
Signs and symptoms
Acute infection with hepatitis B virus is associated with acute viral hepatitiswhich is an illness that begins with general ill-health, loss of appetite,nausea, vomiting, body aches, mild fever, dark urine, and then progresses todevelopment of jaundice.It has been noted that itchy skin has been an indication as a possible symptomof all hepatitis virus types. The illness lasts for a few weeks and thengradually improves in most affected people. A few patients may have more severeliver disease (fulminant hepatic failure), and may dieas a result of it. The infection may be entirely asymptomatic and may gounrecognized.
Chronic infection with hepatitis B virus may be either asymptomatic or maybe associated with a chronic inflammation of the liver (chronic hepatitis),leading to cirrhosisover a period of several years. This type of infection dramatically increasesthe incidence of hepatocellular carcinoma (liver cancer).Chronic carriers are encouraged to avoid consuming alcohol as it increasestheir risk for cirrhosis and liver cancer. Hepatitis B virus has beenlinked to the development of Membranous glomerulonephritis (MGN).