Hepatitis is an inflammation of the liver. It is a common condition, affecting many hundreds of millions…
What is hepatitis B?
Hepatitis B is an inflammation of the liver caused by the hepatitis B virus (HBV). Hepatitis B can result in serious health issues, including liver failure and death. About two billion people are infected with hepatitis B and it is responsible for over a million deaths worldwide every year worldwide.  
The virus can spread in several ways, including through sexual contact, blood-to-blood contact and from mother to child at birth. Common symptoms of hepatitis B infection can include fatigue, fever, loss of appetite, nausea and vomiting, dark urine and jaundice.
Hepatitis B infection is hard to detect without specific testing, since most people infected with the virus show no symptoms, or only mild ones. In addition, the symptoms that do appear can take a long time - years or even decades - to do so. There are, however, reliable diagnostic tests for hepatitis B.
Most people who are infected recover completely from the symptoms after a few months. About a quarter of people who are infected manage to clear the virus. The infection is 'resolved' and they remain healthy and non-infective.
However, the remaining three quarters of people infected do not clear the virus from their body after the symptoms go away. These people remain chronic carriers of the hepatitis B virus. In children who were infected at an early age, the chance of becoming chronic carriers can be high, up to 90% in newborns.   Adults are much more likely to clear the virus. A quarter of chronic carriers will develop liver disease.
Hepatitis B can be prevented with a vaccination and by taking care to avoid contact with the blood of infected people. Hepatitis B is treated with antiviral drug therapy.
Hepatitis B is caused by the hepatitis B virus, or HBV for short. The virus enters the blood of the newly-infected person and travels to the liver cells where it multiplies and can infect new cells and continue its cycle.
It can be transmitted from person to person through direct blood-to-blood contact, through unprotected sex and from an infected mother to her baby.
Mother-to-child transmission during pregnancy, birth or immediately after birth is a major route of hepatitis B infection, particularly in poorer countries. The newborn comes into contact with the mother's bodily fluids and is infected with the virus.
Hepatitis B can move from person to person via unprotected sex. The chance of this occuring increases when the sexual practice has a higher chance of blood-to-blood contact, such as during anal sex.
Hepatitis B infections can occur through the use of infected needles or unsterilised medical supplies and tattooing equipment. The virus can also be transmitted through infected cuts and open sores. Blood-to-blood contact can occur when sharing other personal items such as razors, toothbrushes or nail scissors.
Blood transfusions, organ transplants and use of blood products can also be a way of transmission. In most countries, organ and blood donations are now routinely screened for hepatitis B to minimise the chances of this happening.
Other infection routes
Hepatitis B can also be transmitted from a carrier to other members of the household. Hepatitis B cannot be transmitted by breastfeeding, sneezing, coughing, sharing cutlery, or casual physical contact such as hugging. On rare occasions, a young child may contract hepatitis B from food that is thoroughly chewed by an infected adult.
Anyone can be infected with hepatitis B. People at particular risk of infection include:
- Babies born to infected mothers;
- Intravenous drug users (past or present);
- Sexual partners of hepatitis B carriers;
- People sharing a household with hepatitis B carriers;
- Blood transfusion recipients, and;
- Healthcare workers exposed to blood.
Acute hepatitis B
The acute phase of hepatitis B can take from a few weeks up to six months after infection to appear. Many people infected with the virus exhibit no symptoms, or only mild ones. However, they can still pass on the infection to others.
The outcome of infection with the hepatitis B virus changes from person to person. In most adults exposed to the virus, the infection clears up naturally with no need for medical treatment and the virus is no longer present in their body. Children are much less likely to clear the virus.
Chronic hepatitis B
For infected people in whom natural clearance does not occur, the virus will remain in the body indefinitely, unless treated. This is known as chronic hepatitis B infection.
People with a chronic hepatitis B infection are able to transmit the virus to other people, but most of them show few, if any, signs of trouble throughout their lives. However, some people with chronic hepatitis B go on to develop serious complications, which may result in death (see below). The risk of developing these complications is higher in babies and children.
Signs and symptoms
The liver can sustain a fair amount of damage before it starts malfunctioning. As a result, in many conditions affecting the liver, the signs and symptoms are slow to appear. Signs and symptoms of hepatitis B, if they appear at all, typically do so after an incubation period of 45 to 160 days. 
A hepatitis B infection can be divided into two phases: acute and chronic. The acute phase appears a few weeks or months after infection. The chronic phase appears only in a minority of people with hepatitis B. It can appear months, years or even decades after infection.
About three quarters of people infected with hepatitis B have no symptoms in the weeks after the infection occurs and feel completely healthy. In the months and years following infection, symptoms of chronic hepatitis B can gradually appear. In many people, symptoms do not ever appear at all, or are only mild. In others, symptoms can become serious and have a significant effect on the infected person's life.
Symptoms of acute hepatitis B include:
- Fatigue, weariness;
- Loss of appetite;
- Nausea and vomiting;
- Dark urine;
- Muscle and joint pain;
- Jaundice - a yellowing of the skin and/or eyes (this only appears in one of every five people);
- Fever, and;
- Pain in the liver - the upper right area of the abdomen, under the ribs.
Methods for diagnosis
Hepatitis B is diagnosed through one or a series of blood tests. These tests can measure liver function, detect the presence of the HBV virus in the blood, or of the antibodies the body's immune system produces in response to the virus.
The hepatitis B virus can often be hard to detect soon after infection has occurred. It may take several months before the presence of virus particles, or the body's immune reaction to them, are reliably detectable by blood tests.
Of the people suffering from chronic hepatitis B, most have few or no symptoms throughout their lives. However, 15-40% will suffer significant liver damage, including scarring of the liver, or cirrhosis, that seriously affects their health.  
A minority (an estimated 5-15% over a period of five years    ) of people who develop cirrhosis from a hepatitis B infection may develop liver cancer, termed hepatocellular carcinoma. Liver cancer is the leading cause of death in people with chronic hepatitis B.
Types of treatment
Most people with hepatitis B do not require treatment. In many cases, the HBV virus remains inactive and does not cause problems. In those cases, the person diagnosed with hepatitis B will not need to take any medication, but will be tested every six months to make sure the virus has not become active. There is no specific treatment for the acute phase of hepatitis B; rest, good nutrition and hydration can help the body recover.
Severe and chronic hepatitis B may be treated with antiviral drug therapy and is generally given over a number of years. Treatment can reduce the levels of the virus and help the body 'seroconvert' - that is, help the body build up protective antibodies to the virus. Not everybody seroconverts and those that do can sometimes relapse after treatment. If there is a favourable response to treatment, liver damage, cirrhosis and hepatocellular carcinoma are less likely.
The best protection against hepatitis B is vaccination, now routinely given to babies in many countries. Vaccinations are also available for unvaccinated adults who belong to a high-risk group. Pregnant women are checked for hepatitis B infection as a part of regular blood tests.
If you are infected with hepatitis B, you can prevent transmitting the disease on to others by:
- Practising safe sex and good hygiene;
- Avoiding donating blood or organs;
- Avoiding sharing of needles, razors, toothbrushes, nail scissors, etc.;
- Telling health professionals who treat you about your condition, particularly doctors, dentists, nurses and others who might come into contact with blood;
- Dressing wounds and cuts and disposing of any bloodstained items safely, and;
- Avoiding getting tattoos or body piercings.
Reducing the chance of complications
Measures that can reduce the chances of people infected with hepatitis B from developing complications of the condition include:
- Reducing alcohol consumption;
- Maintaining a healthy diet low in fat, and;
- Not smoking and not using recreational drugs.