What is hepatitis B?|
Hepatitis B is inflammation of the liver due to infection of the hepatitis B virus (HBV). The disease ranges from mild to severe. Infected liver cells (hepatocytes) are destroyed by the body's immune system to prevent the virus from spreading, but too much destruction impairs the vital functioning of the liver leading to potentially serious complications.
The hepatitis virus is present in the blood stream and other body fluids such as vaginal discharges, seminal fluid, breast milk and saliva of infected persons. Because of the extremely high concentration of the virus in blood and body fluids, even slight exposure can result in infection. There are several ways transmission can occur, and specific groups of people are particularly at risk:
- Health workers are at risk of accidental inoculation of infected blood during medical, surgical and dental procedures.
- Heroin or other intravenous drug users can become infected by sharing needles.
- Inadequately sterilized equipment used for immunization, tattooing, and ear and body piercing may also cause infection.
- Hepatitis is a sexually transmitted disease (STD) and so people with multiple sex partners, and male homosexuals are particularly at risk of infection.
- Ninety eight percent of children born to carrier mothers may are infected during delivery. This is generally mild, and can be further reduced by injection of HBV antibody. However, 95% of babies infected develop chronic hepatitis later in life.
- Long periods of contact with infectious people within households, homes and institutions can result in transmission of HBV.
- Inadequate screening of blood donation may cause transmission through the general blood supply.
Symptoms of liver inflammation
After infection with HBV there is an incubation period of 1-6 months (before symptoms first appear). Symptoms, when they start, may include a low-grade fever, chills, tiredness, aching joints and muscles, nausea, vomiting, and weight loss. Diarrhoea or constipation may occur, and the patient may experience abdominal pain and tenderness - usually mild, but aggravated by jarring or exertion.
Dark urine and clay-colored stools may be noticed by the patient from 1 to 5 days before the onset of jaundice. Jaundice generally appears 5-10 days after onset of symptoms, however, it may be present from the start, or may never develop at all. Jaundice refers to the yellowing of the skin and body fluids which occurs when the liver is unable to get rid of bile pigments due to disturbances in the function of its cells.
Symptoms worsen after the onset of jaundice, but the acute illness usually subsides after 2 weeks. Jaundice and abdominal pain disappear, appetite returns, and the patient progressively improves, with complete recovery by 16 weeks. Approximately 10% of patients are unable to eliminate HBV from their system, and may develop chronic hepatitis, cirrhosis or cancer of the liver. Overall mortality is less than 1%, though this is greater in the elderly.
Symptoms of Hepatitis B may be misinterpreted as influenza, and so a diagnosis is made by a blood analysis to detect one of the viral antigens: hepatitis B surface antigen (HbsAg). HbsAg is common in the acute stage, but may be undetectable in some patients in later stages, in which case hepatitis B core antigen (HBcAg) is used for diagnosis.
Blood clotting tests can be used to test the liver's functioning ability, and the presence of certain enzymes in the blood indicate levels of liver damage.
Acute hepatitis usually clears spontaneously within a few weeks of infection and most patients will recover completely. No specific anti-viral therapy is required, though treatment with alfa interferon appears to decrease the risk of chronic hepatitis.
Hospitalisation is generally not