What is hepatitis B?

Hepatitis B is an infectious disease caused by the hepatitis B virus (HBV), resulting in inflammation of liver cells (hepatitis). Since HBV is present in blood, semen, and breast milk, hepatitis B is considered a sexually transmitted disease.

Causes

Transmission can occur through:

sexual intercourse without condoms with an infected person
from an infected mother to her child during pregnancy, childbirth, or breastfeeding (known as vertical transmission)
sharing drug-use materials (syringes, needles, pipes), personal hygiene items (razors, toothbrushes, nail clippers, or other sharp objects), or tattoo and piercing equipment
hemodialysis
transfusion of contaminated blood

Important: The likelihood of HBV transmission is much higher than that of the AIDS virus—approximately 30%.

Incidence

Hepatitis B is endemic in Brazil, with a highly heterogeneous distribution, being more prevalent in the northern and southeastern regions, despite the introduction of the vaccine in the Amazon in 1989 and ongoing immunization and prevention efforts through the Unified Brazilian Public Health System (SUS). It is estimated that 15% of the Brazilian population has been infected, and 1% are currently chronic carriers of the disease.

Types

Hepatitis B can present as either acute (lasting less than six months) or chronic.

In the acute form, which accounts for the majority of cases, the incubation period ranges from 30 to 180 days. The first symptoms include malaise, body aches, loss of appetite, and fever, followed by jaundice (yellowing of the skin), itching, dark urine, and pale stools. These symptoms usually subside within approximately six weeks, and in most cases, the patient becomes immune to the virus.

Progression to the chronic form depends on the age at which the infection occurs and the individual's immune response. Children are the most affected: in those under one year of age, the risk reaches 90%; between one and five years, it ranges from 20% to 50%. In adults, the rate drops to between 5% to 10%. Chronic hepatitis B is also more commonly observed in individuals who consume alcohol and those who are immunocompromised. In its chronic form, the disease is usually asymptomatic.

Diagnosis

Hepatitis B is diagnosed through a specific blood test (viral serology), along with viral load testing. After a positive result, the doctor will recommend appropriate treatment. In chronic cases, the disease may progress to cirrhosis (scarring of the liver that impairs its function, caused in this case by chronic inflammation from the hepatitis B virus or other causes such as alcohol use, hepatitis C, autoimmune hepatitis, etc.) and even liver cancer. In such cases, additional tests may be needed, such as liver imaging (CT scan or abdominal ultrasound) or even a liver biopsy. Nowadays, non-invasive tests that measure the degree of fibrosis, such as Fibroscan® elastography or MRI elastography, can also be used, avoiding or delaying the need for biopsy.

Prevention

The best way to prevent hepatitis B is through vaccination. The vaccine is given to individuals who have not yet developed the disease. It is safe and effective and is usually administered in 3–4 doses over a 6-month period. After completing the three doses, the hepatitis B vaccine provides over 90% protection for infants, children, and adults. All children should receive the first dose at birth and complete the three-dose series by six months of age. Unvaccinated adults should update their immunizations. People at high risk of infection, including healthcare workers and those living with someone who has hepatitis B, should also be vaccinated. Newborns of mothers infected with hepatitis B should receive special immunization, including hepatitis B immunoglobulin and the hepatitis B vaccine within the first 12 hours of life. Screening of all donated blood has reduced the risk of hepatitis B transmission through transfusion. Mandatory reporting of the disease allows healthcare professionals to monitor individuals exposed to the virus. The vaccine or hepatitis B immunoglobulin (HBIG) can help prevent infection if administered within 24 hours of exposure.

Prevention guidelines for viral hepatitis should be shared with household contacts and sexual partners. Prevention requires safe practices—such as proper condom use and avoiding the sharing of sharp instruments and personal hygiene items like toothbrushes, nail clippers, and razors. The World Health Organization recommends that mothers with chronic hepatitis B continue breastfeeding (consult a specialist if in doubt).

Treatment

For acute cases, in addition to medication (when necessary), it is recommended to stop consuming alcohol and use medications to relieve symptoms such as vomiting and fever.

Treatment for chronic cases depends on the presence or absence of cirrhosis, viral replication (virus multiplication in the blood), and the patient’s clinical condition. Currently, several antiviral medications are available (including interferon, lamivudine, tenofovir, and entecavir), most of which are taken orally (except for interferon, which is subcutaneous), and are provided by the SUS. In more severe cases, when cirrhosis is already present or cancer develops, a liver transplant may be necessary.

By Einstein Editorial Board