The virus is found in blood and body fluids and is transmitted through access to a non-infected individual's mucus membranes or bloodstream. HBV is a major global health problem, with an annual death toll similar to that of malaria.
For most people, hepatitis B is a short-term illness that causes no permanent damage. For others, it can become a chronic infection that can potentially lead to liver cancer.
HBV infection can be prevented with immunization, and chronic infection can be successfully treated with antiviral medication.
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You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories. Also look out for links to information about related conditions.
Here are some key points about hepatitis B. More detail and supporting information is in the main article.
- The rate of new HBV infections has declined by approximately 82% since 1991.
- Up to 2 million persons in the United States have chronic hepatitis B virus infection.
- Ten distinct genotypes of HBV (A to J) have been identified.
- Risk for chronic infection is related to age at infection: 90% of infected infants become chronically infected, compared with 2-6% of adults
- HBV is blamed for at least 5,000 deaths in the US annually
- The HBV can survive outside the body at room temperature, on environmental surfaces, for up to 7 days
- HBV is an occupational hazard for health workers
- It is not uncommon for individuals to remain undiagnosed with HBV until they show signs of end stage liver disease
- In 1991, universal vaccination of all babies against HBV was adopted
- Over 1 billion doses of HBV vaccine have been used worldwide.
What is hepatitis B?
Hepatitis B is a virus that can infect and inflame the liver. It is a DNA virus that integrates into the chromosomes (genome) of an individual. HBV is particularly dangerous because it can infect people without them knowing it, and, in turn, those infected can unknowingly pass the virus to others.
Some individuals remain chronically infected with the virus past the initial infection period. For those who become chronically infected, the virus can continuously attack the liver over time without being detected, causing potentially irreversible liver damage.
Rates of infection are highest among males aged 25-44 years. In 2013, an estimated 19,764 persons in the US were newly infected with hepatitis B. Globally, it is estimated that more than 2 billion people have been infected with HBV. 240 million people have chronic infection, and roughly 600,000 persons die from HBV-related liver disease each year.
Causes of hepatitis B
The hepatitis B virus is transmitted in the bodily fluid of individuals with the infection.
Hepatitis B is transmitted when blood, semen or another body fluid from a person infected with the virus enters the body of someone who is not infected, whether it is through a puncture in the skin, a shared needle or the exchange of body fluids.
This can happen through mother to baby at birth, sex with an infected partner, sharing needles, syringes, or other drug-injection equipment, unsafe tattoo techniques or even from sharing personal hygiene items such as razors or toothbrushes. Unsafe medical practices, such as reusing medical equipment, can also lead to HBV infection.
Hepatitis B is not spread through food or water, sharing eating utensils, breastfeeding, hugging, kissing, holding hands, coughing, sneezing or by means of insects that bite.
The HBV can survive outside the body for at least 7 days. During this time, the virus can still cause infection if it enters the body of a person who is not protected by the vaccine.
Symptoms of hepatitis B
Most acute hepatitis B infections occur during infancy or childhood and are rarely diagnosed due to the lack of obvious symptoms. The average time from exposure to symptom onset is 90 days after exposure to the virus has occurred.
Other possible symptoms of acute HBV infection include:
- Dark urine
- Clay-colored bowel movements
- Jaundice (yellow tinge of the skin and eyes).
Tests and diagnosis of hepatitis B
A blood test is available to diagnose both acute and chronic HBV infection.
A hepatitis B infection can be diagnosed with a blood test.
Certain populations are at either an increased risk of becoming infected with hepatitis B or at risk of developing complications from undiagnosed HBV infection.
The following groups should be screened for hepatitis B:
- Infants born to mothers with HBV
- Sex partners of infected persons
- Sexually active persons who are not in a long-term, mutually monogamous relationship
- Men who have sex with men
- Injection drug users
- Household contacts of persons with chronic HBV infection
- Health care and public safety workers at risk from occupational exposure to blood or blood-contaminated body fluids
- Hemodialysis patients
- Residents and staff of facilities for people with developmental disabilities
- Individuals originally from Africa, Asia, India, Pakistan or Eastern Europe
- All patients who will receive chemotherapy for cancer.
Additionally, it is vital that all pregnant women be screened for hepatitis B; if found to be positive, it is critical that the baby is vaccinated and receives hepatitis B immune globulin (HBIG) within 12 hours of birth.
On the next page, we look at chronic hepatitis B infection, the available treatment options and methods of preventing the condition.