download / swf / 252Kb
Hepatitis B is an infectious illness caused by hepatitis B virus (HBV) which infects the liver of hominoidea, 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 quarter 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 such as semen and vaginal fluids, while viral DNA has been detected in the saliva, tears, and urine of chronic carriers with high titer DNA in serum. Perinatal infection is a major route of infection in endemic (mainly developing) countries.[5] Other risk factors for developing HBV infection include working in a health care setting, transfusions, and dialysis, acupuncture, tattooing, extended overseas travel and residence in an institution. [6] [3][7] However, Hepatitis B viruses cannot be spread by casual contact, such as holding hands, sharing eating utensils or drinking glasses, breast-feeding, kissing, hugging, coughing, or sneezing.
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.
0 komentar:
Leave a Reply