Hepatitis B is caused by the hepatitis B virus (HBV). It is a viral infection that affects the liver and can lead to both acute and chronic liver disease. The virus is typically transmitted through contact with the blood, semen, vaginal fluids, and other body fluids of an infected person. Here are the primary modes of transmission for hepatitis B:

1. Mother-to-Child Transmission: A pregnant woman infected with hepatitis B can pass the virus to her baby during childbirth. To prevent this, newborns are often given the hepatitis B vaccine and hepatitis B immune globulin (HBIG) shortly after birth if their mothers are infected.
2. Sexual Contact: Hepatitis B can be transmitted through unprotected sexual intercourse with an infected partner. It is considered a sexually transmitted infection (STI).
3. Contact with Infected Blood: Sharing needles or syringes with an infected person, which can occur with drug use, is a common mode of transmission. Healthcare workers can also be at risk if they are accidentally stuck with a needle contaminated with hepatitis B-infected blood.
4. Use of Contaminated Medical Equipment: Inadequately sterilized or reused medical equipment, such as needles or surgical instruments, can transmit the virus if they come into contact with an infected person’s blood.
5. Sharing Personal Items: Sharing personal items that may have small amounts of an infected person’s blood on them, such as razors or toothbrushes, can lead to transmission.
6. Organ Transplants and Blood Transfusions: Although rare, hepatitis B can be transmitted through organ transplants and blood transfusions from infected donors. Stringent screening and testing of donated blood and organs have significantly reduced this risk.
7. Tattooing and Body Piercing: If the equipment used is not properly sterilized or if there is a lapse in infection control practices, hepatitis B transmission can occur during tattooing or body piercing.

It’s important to note that not all individuals infected with hepatitis B will develop symptoms, especially during the acute phase of the infection. Some may remain asymptomatic carriers of the virus, while others may experience mild to severe symptoms, which can include fatigue, jaundice (yellowing of the skin and eyes), abdominal pain, nausea, and loss of appetite.
To prevent hepatitis B, vaccination is highly effective and recommended. The hepatitis B vaccine is part of routine immunizations in many countries. Practicing safe sex, using clean needles and avoiding sharing personal items that may come into contact with blood are also essential precautions to prevent the transmission of the virus. If someone is exposed to the virus or is at risk, they should seek medical evaluation and possibly receive post-exposure prophylaxis.