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Hepatitis B
Hepatitis B virus (often known as HBV) is an infection that can cause severe and even fatal damage to your liver.
It is a very common infection around the world, particularly in Africa and the Indian sub-continent. At some London HIV clinics as many as 6% of gay men are co-infected with both hepatitis B and HIV. It is also common in people who have shared injecting equipment.
Transmission
The reason why so many people with
HIV also have hepatitis B is because it can be spread in a similar way to HIV, particularly by contact with blood, semen and vaginal fluid, and from a mother to her baby whilst pregnant.
Hepatitis B is many times more
infectious than HIV and it can also be spread in saliva.
In richer countries, such as the UK, hepatitis B has mainly affected gay and bisexual men, injecting drug users, and people with haemophilia. Increasing numbers of cases are being seen in people from Africa and India.
It is very important that people with HIV are vaccinated against hepatitis B. Using a condom for anal, vaginal and oral sex reduces the chances of hepatitis B being passed on during sex. Similarly, you should never share needles or other injecting
drug equipment.
Bloods products in the UK are routinely screened for hepatitis B.
Symptoms
The majority of adults who are infected with hepatitis B have no symptoms to suggest that they have the infection, and it is often only diagnosed by routine blood tests.
However, if symptoms do occur after infection you may experience a yellowing of the skin and whites of the eyes (jaundice), loss of appetite, pain in the stomach, nausea and vomiting, have a temperature, joint and muscle aches and feel generally unwell.
These symptoms can be very severe and in some very rare cases can cause death.
Stages of infection
There are four stages of hepatitis B infection.
- Immune tolerance – at this stage hepatitis B is able to reproduce freely in the body, even though it does not cause any symptoms. This stage tends to last for several weeks in adults after they become infected with hepatitis B and for years in infants after infection.
- Immune response – during this stage the body's natural defences, the immune system, attacks the hepatitis B-infected cells in the liver and starts to clear the infection from the body. In some people who have been recently infected with hepatitis B this phase may last for no more than a few weeks. However, in people who cannot clear the infection it can last for years. Many people develop symptoms and become unwell at this time.
- Viral clearance – this is often also known as 'seroconversion' because the body produces antibodies in response to a substance on the surface of the hepatitis B virus called the 'e' antigen. During this stage hepatitis B stops reproducing itself.
- Immunity to hepatitis B – this is when the immune system produces a full antibody response to hepatitis B, and clears the body of hepatitis B virus. Hepatitis B genetic material (DNA) usually disappears from the body.
If the last two stages do not occur, you will be left with persistent infection and liver damage.
Monitoring
There are a number of tests to see if you are infected with hepatitis B, or if you have been infected, and have managed to clear the infection.
If tests find fragments of hepatitis B virus called surface antigens for more than six months, then you are a chronic carrier of hepatitis B and are potentially infectious to other people.
People who are 'e antigen positive' have higher rates of replication of hepatitis B and are also likely to be more infectious.
If you have antibodies but no antigen after six months of infection, then your immune system has cleared hepatitis B infection.
You are also likely to have regular tests to see if your liver has been affected by hepatitis B. These are called liver function tests and they look at levels of certain proteins and enzymes which give an indication of how well your liver is
working. They should be performed at least every six months.
Ultrasound examinations are also used, particularly if your liver is damaged. In some cases it may be necessary to perform a liver biopsy, when a tiny sample of tissue from the liver is extracted using a hollow needle for examination under a microscope.
Treatments
Treatments are available if you do not clear infection with hepatitis B. There are currently three drugs licensed for the treatment of hepatitis B in the UK. These are alpha interferon, the anti-HIV drug 3TC (lamivudine, Epivir) and adefovir (Hepsera).
The aims of hepatitis B treatment are to reduce liver inflammation, reduce the amount of hepatitis B DNA, and ideally, to eradicate hepatitis B antigens from the body and produce antibodies that reduce the risk of progression to cirrhosis and liver damage.
In people who only have hepatitis B these treatments usually eradicate hepatitis B in about a third of the people who take them.
Alpha-interferon
Alpha interferon is given by injection, usually three times a week for four months, and leads to clearance of detectable hepatitis B in between 20 – 40% of people with hepatitis B infection alone. However, it works less well in men, people who have had hepatitis B for a long time, people who have large amounts of hepatitis B DNA, and people who are also infected with HIV.
Alpha interferon can cause unpleasant side-effects, including flu-like symptoms, aches and pains, depression, and bone marrow suppression.
3TC
3TC is better known as an anti-HIV drug, but also works against hepatitis B and is licensed for the treatment of both infections. The dose of 3TC for hepatitis B treatment is 100mg taken orally once daily. This is lower than the twice daily 150mg dose of 3TC used when the drug is included in anti-HIV drug combinations. 3TC should never be given as monotherapy (the only drug) to people who have hepatitis B and HIV coinfection if they have a detectable HIV viral load as the low dose could lead to 3TC resistance developing.
3TC treatment results in viral clearance of hepatitis B in about 20 – 30% of those who take it. It is not known how long it is necessary to take 3TC for, and although studies have generally looked at people taking the drug for a year or two, lifelong therapy with the drug may be needed.
Adefovir
Adefovir (Hespera) has recently been approved as a treatment for hepatitis B in Europe and the US. The standard dose is 10mg, and the drug is effective against hepatitis B virus that is resistant to 3TC. Side-effects include headache, stomach pain, feeling sick, and diarrhoea. Adefovir has previously been tested as an anti-HIV drug at 60mg and 120mg doses, but was not licensed because (at these doses) the risk of kidney toxicity was too great
Hepatitis B and HIV
It was generally thought that having hepatitis B did not make HIV hasten or worsen HIV disease progression and severity.
However, liver disease due to hepatitis B or C has emerged as a significant cause of illness and death in people with HIV since the introduction of effective anti-HIV drugs (sometimes called highly active antiretroviral therapy, or HAART) brought a longer and healthier life for many people with HIV.
HAART and hepatitis B
HAART can be used safely and effectively if you have hepatitis B.
However, when some HIV and hepatitis B coinfected people start taking HAART they may experience a short-term flare-up of hepatitis B. This is usually the consequence of HAART restoring the immune system, which then becomes better at responding to infections such as hepatitis B. This improved immune response can lead to active hepatitis B disease.
To try and prevent these flares happening, many doctors recommend that people with chronic hepatitis B infection who are starting HAART should start treatment for hepatitis B infection at the same time.
People with hepatitis B appear to be at greater risk of experiencing the increases in liver enzymes which some anti-HIV drugs can cause. The drugs particularly associated with liver side-effects are ritonavir, indinavir, nevirapine, AZT, ddI, as well as some drugs used to treat other infections to which people with HIV can be vulnerable, including pentamidine, some sulphur-based antibiotics, and ketaconazole.
Hepatitis B treatment if you have HIV
The British HIV Association, the organisation that sets UK guidelines for the treatment of HIV, recommends that if a person with hepatitis B virus is taking HAART, then this should include an anti-HIV drug that is also effective against hepatitis B. These are 3TC and tenofovir. Some doctors think that an anti-HIV regimen that combines 3TC and tenofovir may be a very effective treatment for both HIV and hepatitis B. Studies to investigate this are currently underway. Another HIV drug that is effective against hepatitis B is FTC (emtricitabine). It has recently been approved for use in the UK.
Because of the possibility of resistance, anti-HIV drugs should not be used for the treatment of hepatitis B if a person is not taking HAART. In these circumstances alpha interferon or adefovir should be