Hepatitis B is transmitted by the hepatitis B virus, which causes inflammation of the liver. The disease is usually transmitted through sexual or blood contact. The disease is rarely noticeable by symptoms as it progresses.
What is hepatitis B virus?
Hepatitis B is an inflammation of the liver caused by the hepatitis B virus. In most patients, an acute course of the disease can be observed that heals on its own. In addition, serious manifestations, such as liver cancer, gastrointestinal bleeding or liver cirrhosis, cannot be ruled out. The disease can be chronic or acute. Liver inflammations are caused by damage to liver cells. These can limit the function of the organ. Hepatitis B is one of the most common infectious diseases. Worldwide, one in three people is said to be infected. Due to transmission during pregnancy, the risk of infection is particularly high in some areas. If left untreated, the late effects of a hepatitis B infection are particularly relevant. To avoid infection, vaccination can be considered prior to long-distance travel. The individual hepatitis B virion is protected by a specific envelope. This contains various proteins, such as the membrane protein and the Pre-S1 protein. The Pre-S1 protein enables the virus to enter a host cell. Overall, the hepatitis B virus is one of the smaller viruses with its diameter of 42nm.
Occurrence, distribution and characteristics
Hepatitis B is prevalent worldwide and thus poses a risk of disease to consider during long-distance travel. Regionally, most cases of the disease are recorded in Africa as well as in East Asia. Chronic hepatitis B can be localized in areas near the Amazon and in Eastern and Central Europe. According to experts, up to 20 percent of the population in China and Central Africa is believed to suffer from hepatitis B, compared to less than one percent in Western European and North American countries. One-third of the population worldwide has suffered from hepatitis B infection. 780,000 people die each year as a result of acute or chronic hepatitis B infection. The virus is transmitted through contact with all body fluids such as semen, saliva and blood. Thus, affected individuals who are unaware of their disease pose a particular risk of infection. In some regions, the virus is also transmitted through contaminated material during medical treatments. The virus is said to be 50 to 100 times more contagious than the one that leads to HIV. Hepatitis B viruses have only about 3000 bases, making them a million times smaller than the human genome. Despite its unusual size and shape, the virus manages to spread efficiently. From only four genes, it can produce seven proteins, which in turn can have different structures. The hepatitis B virus produces a DNA copy from a viral RNA and transports it out of the cell as packaged virions. The resulting envelope protects the viral genome from damage and contributes to the transport of the virus within the host.
Diseases and medical conditions
Hepatitis B is caused by the hepatitis B virus. This is a virus with double-stranded DNA. Humans are the only possible host. Because a particularly large number of the viruses are found in the blood, this in particular is considered to be infectious. Even drops of blood are sufficient for infection. In other body fluids, such as semen or saliva, the concentration of the virus turns out to be lower. The incubation period for hepatitis B virus is between one and six months. The incubation period is the time until the first symptoms appear after infection. Overall, the course of hepatitis B disease varies greatly. In one third of all patients, no symptoms are noticeable at all. For this reason, the disease is not recognized and those affected pose a particular risk to healthy people. If symptoms do occur, they are increasingly general signs of illness that cannot always be immediately attributed. Those affected complain of fatigue, headaches, loss of appetite, weight loss, fatigue, muscle and joint complaints, and fever.Once the cells of the liver have been damaged, other symptoms may appear: Darkening of the urine, light coloring of the stool, discoloration of the skin and eyes. These specifically indicate an underlying jaundice. If the disease remains untreated, serious late effects can occur. If in doubt, it is advisable to consult a doctor. How severe the hepatitis B disease is depends on various factors. These include, above all, the patient’s age and general state of health. In adults, the disease often heals on its own and has a favorable overall course. Young children and people with weakened immune systems, on the other hand, suffer more frequently from the acute disease becoming chronic. Chronic hepatitis B leads to the fact that affected persons are permanently infectious under certain circumstances. This condition does not always manifest itself through corresponding symptoms. In addition, the liver values are permanently elevated and there may be severe consequential damage. These include, for example, liver cirrhosis and liver cancer. Liver cirrhosis is the final stage of liver disease that has destroyed the structure of the organ. The tissue hardens, shrinks and becomes increasingly scarred. The function of the liver is further reduced, which can lead to life-threatening symptoms. Different medical approaches can improve the condition of the liver. However, in the case of advanced liver cirrhosis, liver transplantation is often the only option. In the case of liver cancer, the timing of diagnosis in particular determines the patient’s prognosis. The earlier the tumor is detected, the better the chances of survival. If surgery is necessary, the chances of surviving more than the first five years are 20 to 50 percent. However, liver cancer is detected late in many patients. Often, a cure is then no longer possible because the tumor has already metastasized. Hepatitis B can therefore have serious consequences. Vaccination efficiently prevents infection. The active substance is administered at two appointments, each two weeks apart, and is usually well tolerated. For long-term protection, a third vaccination is recommended after six months. It is possible to have children vaccinated as infants. Vaccination is also important for risk groups. These include people with weakened immune systems, such as HIV-infected individuals, as well as people who have an increased risk of infection due to their occupation.
