Quick Answer
Hepatitis B occurs when blood, semen, or vaginal fluid from a person carrying the hepatitis B virus enters the bloodstream or a mucous membrane of someone who is not immune. The virus then travels to the liver and infects liver cells, where the immune system's response causes inflammation. It is not spread by food, water, coughing, or casual contact - that route belongs to hepatitis A.
- Hepatitis B spreads through blood, semen, and vaginal fluids, not food or water.
- Hepatitis A is fecal-oral; hepatitis C is spread mainly through blood.
- A mother with hepatitis B can pass the virus to her newborn during delivery.
- Sharing needles, syringes, razors, or toothbrushes can transmit hepatitis B.
- Most adults who get hepatitis B recover; infected infants often develop lifelong infection.
- A vaccine given in a series of doses prevents hepatitis B.
Context Most Pages Skip
Hepatitis simply means inflammation of the liver, and many things cause it - viruses, alcohol, medications, autoimmune disease, and fat buildup. The hepatitis B virus is one specific cause. What makes it unusual is how it damages the liver: the virus itself is not highly toxic to liver cells. Instead, it slips inside them, copies itself, and the immune system's attack on infected cells produces the inflammation. That is why liver injury can continue quietly for decades while a person feels well, and why the infection looks so different in a newborn, whose immune system barely reacts, than in an adult.
Frequently Asked Questions
How does hepatitis occur?
Hepatitis B occurs when blood, semen, or vaginal fluid from a person carrying the hepatitis B virus enters the bloodstream or a mucous membrane of someone who is not immune. The virus then travels to the liver and infects liver cells, where the immune system's response causes inflammation. It is not spread by food, water, coughing, or casual contact - that route belongs to hepatitis A.
Why does hepatitis occur?
Hepatitis B occurs when blood, semen, or vaginal fluid from a person carrying the hepatitis B virus enters the bloodstream or a mucous membrane of someone who is not immune. The virus then travels to the liver and infects liver cells, where the immune system's response causes inflammation. It is not spread by food, water, coughing, or casual contact - that route belongs to hepatitis A.
Can hepatic cirrhosis occur in people who do not drink?
Hepatitis B occurs when blood, semen, or vaginal fluid from a person carrying the hepatitis B virus enters the bloodstream or a mucous membrane of someone who is not immune. The virus then travels to the liver and infects liver cells, where the immune system's response causes inflammation. It is not spread by food, water, coughing, or casual contact - that route belongs to hepatitis A.
Related Questions
Sources & Further Reading
- CDC — Sexually Transmitted Infections
- CDC STI Treatment Guidelines
- WHO — Sexually transmitted infections fact sheet
- MedlinePlus — Sexually Transmitted Diseases
Figures reflect CDC surveillance and WHO estimates; they are population statistics, not personal risk predictions.