Hepatitis B Basics
What is hepatitis B?
Hepatitis B (HBV) is a virus that infects the liver. There are two categories of disease due to HBV infection: acute Hepatitis B and chronic Hepatitis B. Acute HBV is a short term illness that occurs within the first 6 months of infection, and then may be cleared by the immune system. If it is not cleared by the immune system, it may lead to chronic hepatitis B infection. Chronic hepatitis B infection may be symptomless for decades, but can ultimately lead to life-threatening complications, such as cirrhosis or liver cancer.
Hepatitis B is most common in certain areas of Africa, Asia, Pacific Islands, Eastern Europe, the Middle East, and South America and the Caribbean. Please see this map of the prevalence of chronic hepatitis B infection for more details.
How is hepatitis B spread?
Hepatitis B is transmitted through the blood and bodily fluids of an infected individual. This can take place during sexual contact, sharing of needles, or from mother to baby during birth. HBV can remain infectious outside the body for more than 7 days, so it is important for infected individuals to maintain their personal hygiene and a level of cleanliness in their surroundings. This means cleaning and covering wounds and sores, and cleaning up spilled blood and other bodily fluids with a mixture of 1 part bleach to 10 parts water. Sharing toothbrushes and razors should be avoided.
Hepatitis B is not spread through food, water, sharing eating utensils, hugging, kissing, hand holding, coughing, or sneezing. It is also not spread by breastfeeding, but as it may be spread through blood, breastfeeding should be stopped if the baby is biting the mother.
Why do some infected individuals develop a chronic infection, while others clear the virus at the acute stage?
The risk of developing chronic hepatitis B disease is related to the strength of the immune response to the infection. A stronger immune response means that the virus is more likely to be cleared. As babies and young children have weaker immune systems than adults, the age at which an individual first contracts the virus plays a significant role in the progression of the disease. Approximately 90% of infected infants will become chronically infected, compared to only 2%–6% of adults.
This also means that people who have compromised immune systems, for example due to certain medical conditions or treatments, may be at higher risk of developing chronic infection after exposure.
What are the signs and symptoms of hepatitis B?
Many individuals who are acutely infected with hepatitis B virus may not experience any signs or symptoms of their infection. Most others may experience very mild symptoms that can be mistaken for the flu, such as fever, fatigue, loss of appetite, and nausea and vomiting. More severe symptoms include abdominal pain, dark urine, joint pain, jaundice (yellowing of the skin), and clay-colored bowel movements. These symptoms usually occur within the first six months of infection.
Individuals who become chronically infected with hepatitis B may be asymptomatic for many years or decades. However, damage may be occurring to their livers, which could ultimately lead to cirrhosis or liver cancer.
Is hepatitis B dangerous?
Acute HBV infection may be very uncomfortable or painful, but the disease is not usually fatal. Chronic HBV infection that leads to liver cirrhosis or liver cancer can be fatal. However, regular monitoring and treatment, such as with anti-viral medication, can minimize liver damage in chronically infected individuals. The damage done by HBV infection can also be worsened by the consumption of alcohol, so this should be avoided by all infected individuals.
Who is at risk for hepatitis B?
- Infants born to infected mothers
- Sex partners of infected individuals
- Injection drug users
- Household contacts of persons with chronic HBV infection
- Health care and public safety workers at risk for occupational exposure to blood or blood-contaminated body fluids
- Residents and staff of facilities for developmentally disabled individuals
- Travelers to countries with intermediate or high prevalence of HBV infection
- Men who have sex with men
- Individuals with multiple sex partners