What is the hepatitis B virus?
Hepatitis B virus (HBV) is a virus that causes inflammation of the liver and causes hepatitis B.
This virus is mainly transmitted sexually, but also through needle sharing and mother-to-child transmission during pregnancy or birth. At a more advanced stage, the infection can potentiate the development of serious liver diseases, such as cirrhosis and liver cancer.
The hepatitis B virus has the ability to survive outside the body for about 7 days, remaining active during this period. In the body it is found in the blood and in some bodily secretions (semen, vaginal secretions and saliva).
What is hepatitis B?
Hepatitis B is an infectious disease caused by the hepatitis B virus that attacks the liver and can cause acute or chronic disease.
Most of the time, hepatitis B is acute and does not need any specific treatment, and the virus is eventually eliminated by the immune system. About 95% of healthy adults who are infected with hepatitis B recover and shed the virus after a few weeks, up to 6 months.
However, in about 5% of cases hepatitis B in adults becomes chronic.
What are the symptoms of acute hepatitis?
Many people infected with the hepatitis B virus do not develop any symptoms in the acute phase of infection. When present, symptoms of acute infection can be:
- fever
- abdominal pain
- fatigue
- decreased appetite
- nausea
- Vomiting
- jaundice (yellowing of the skin and eyes)
- dark urine
- pale stools
However, the absence of symptoms is not synonymous with infection control. Usually, chronic hepatitis can cause silent but potentially serious complications.
How is the hepatitis B virus transmitted?
The main routes of transmission of the virus are:
- Sexual route: vaginal, anal and oral (most common form of transmission)
- parenteral route:
- sharing contaminated needles/syringes, tattoos, acupuncture, piercings (if non-sterile material is used)
- sharing toothbrushes, razors, nail clippers or other personal utensils that may contain contaminated blood
- blood transfusions and organ transplantation (rare routes of transmission)
- Vertical transmission (mother-to-child): happens during or immediately after childbirth. Cesarean section does not prevent transmission of the virus.
Although the virus has already been detected in saliva, transmission through kissing is unlikely unless there are sores in the mouth.
What is the incubation period of the virus?
The incubation period of HBV can vary between 30 and 150 days after exposure to the virus.
What are the main complications of hepatitis B virus infection?
In the most severe cases, especially in people with weakened immune systems, the following may occur:
- liver failure, i.e. failure of the liver to function
- cirrhosis
- Liver cancer
- kidney disease
What are the risk factors for hepatitis B virus infection?
There are a few factors that increase the risk of hepatitis B virus infection:
- having multiple sexual partners
- unprotected sex
- not being vaccinated against hepatitis B
How can I prevent the disease?
Hepatitis B is a preventable disease and the main form of prevention is vaccination against the virus.
Infected individuals should take measures to reduce the risk of transmission of the infection, including:
- informing sexual partners about a possible infection
- use condoms correctly and consistently in all sexual intercourse
- Do not share needles, syringes, blades, toothbrushes or other utensils for personal use that may contain blood
- protect all cuts or wounds with dressings
Sexual partners, family members, or other individuals who share the same household should be tested for hepatitis B. All those who are at risk should be vaccinated.
Is there vaccination against hepatitis B?
Yes. Vaccination against hepatitis B is the key element of prevention. Hepatitis B vaccines are safe and 98-100% effective in protecting against infection.
In Portugal, the vaccine has been part of the National Vaccination Program since 1995. It is recommended to administer:
- 1st dose right after birth still in the maternity/hospital
- 2nd dose at 2 months of age
- 3rd dose at 6 months of age
The World Health Organization (WHO) recommends that all children be vaccinated against hepatitis B, ideally within the first 24 hours of life. The effectiveness of this vaccine depends on the administration of all recommended doses.
What is post-exposure prophylaxis?
Post-exposure prophylaxis is an emergency measure to prevent infection with hepatitis B virus after possible exposure to the virus.
In individuals who are unvaccinated or lack immunity against hepatitis B, administration of the hepatitis B vaccine or intravenous immunoglobulin within the first 12 to 24 hours after possible contact with a patient with the virus may reduce transmission. In case of exposure to the virus you should seek immediate medical advice.
How is the disease diagnosed?
The diagnosis of hepatitis B is made by performing blood tests to detect the antigen and antibody and/or the hepatitis B virus.
Tests to assess liver function may also be indicated.
The virus can be detected 1 to 9 weeks after contact and persists in the body for varying periods.
Is there a treatment for hepatitis B?
Acute hepatitis B usually does not require specific treatment, and hydration and rest care are recommended. Medications (antivirals) may be used in special cases. In most cases, the immune system controls the infection and is able to eliminate the virus within about 6 months.
In chronic hepatitis B, antiviral treatment is often recommended, achieving control of the virus in the vast majority of cases. Although it does not cure the infection, it has the potential to reduce liver damage, preventing long-term complications.
Source: Directorate-General for Health (DGS)