Hepatitis B virus

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Hepatitis B virus (HBV) is a small, enveloped virus with partly double-stranded DNA. It causes hepatitis B, an illness that can be short-term or long-term. HBV infects liver cells and can stay in the body for many years, sometimes leading to liver damage, cirrhosis, or liver cancer.

How HBV spreads
- The virus is passed through blood and other body fluids.
- The main routes are from mother to baby at birth, through sex, by sharing needles, or through exposure to contaminated medical equipment.
- It is not spread by eating or drinking, hugging or kissing, or casual contact. Breastfeeding is not a common route of infection.

Who is at risk
- People with multiple sexual partners, people who use intravenous drugs, healthcare workers exposed to blood, and babies born to HBV-infected mothers.
- In areas where HBV is common, many infections occur in infancy or early childhood.

Symptoms and outcomes
- Some people have no symptoms at first. When symptoms occur, they can include fever, fatigue, poor appetite, nausea, and jaundice (yellow skin or eyes).
- Some people clear the virus, but others become chronically infected. Chronic HBV can slowly damage the liver over years and may lead to cirrhosis or liver cancer.
- Co-infection with HIV or hepatitis C can worsen liver damage.

Prevention and treatment
- Vaccination prevents HBV infection. Vaccines are given to infants and to adults at risk.
- Vaccination has greatly reduced HBV in many countries.
- There is no cure, but antiviral medicines can control the virus in chronic cases and reduce liver damage. Regular medical check-ups help manage the disease.

Global impact
- HBV is a worldwide health issue. About 2 billion people have been infected at some point, roughly 350 million live with chronic HBV, and around 1.5 million new infections occur each year. Hundreds of thousands die each year from HBV-related liver disease.

Notes on the virus
- HBV uses a unique replication process and makes several viral proteins that help it enter liver cells and persist in the body. The virus can cause inflammation and long-term liver damage, which is why vaccination and treatment are important.