Hepatitis B is an infection of the liver by the hepatitis B virus. It can be acute and self-resolving, or it can be chronic, leading to cirrhosis and liver cancer.
HBV is a major global health problem. Worldwide, some 887,000 people died from HBV-related liver disease in 2015. Between 850,000 and 2.2 million people in the United States (U.S.) are thought to be living with chronic HBV infection.
For most adults, HBV is a short-term illness that causes no permanent damage, but 2 to 6 percent of adults infected will develop a chronic infection that can potentially lead to liver cancer. Around 90 percent of infants with the virus will develop chronic infection.
There is no cure for HBV, but immunization can prevent initial infection. Antiviral medication can treat chronic infections.
Fast facts on hepatitis B
Here are some key points about hepatitis B. More detail is in the main article.
- Hepatitis B virus (HBV) is a virus that is spread through blood and other bodily fluids.
- Symptoms affect some people for a short time, but others will develop chronic symptoms and complications that can be fatal.
- Up to 2.2 million people in the United States (U.S.) have chronic HBV infection.
- Many cases go unreported or remain undiagnosed until a person shows signs of end-state liver disease.
- HBV can survive for up to 7 days outside the body at room temperature, on environmental surfaces.
- Since 1991, all infants in the U.S. have been vaccinated against HBV.
What is hepatitis B?
HBV can cause infection and inflammation of the liver. A person can be infected and pass on the virus without knowing it.
Some individuals have no symptoms, some experience only the initial infection, but others remain chronically infected, as the virus continues to attack the liver over time without being detected. Irreversible liver damage can result.
In 2014, 2,953 cases were reported to the Centers for Disease Control and Prevention (CDC), but the actual number of acute cases may have been as high as 19,200.
Globally, chronic infection due to HBV is thought to affect 240 million people, and around 786,000 people die from HBV-related liver disease each year.
Causes
Hepatitis B is caused by infection of the body with the hepatitis B virus.
The hepatitis B virus (HBV) is found in blood and bodily fluids. It can be transmitted through semen, vaginal fluids, and blood, and it can pass from a mother to a baby during delivery. Sharing needles and having unprotected sex increase the risk.
People tend to catch HBV when they visit a part of the world in which infection is more common.
A person can spread the condition without being aware, as it may be symptomless.
Transmission
Hepatitis B is transmitted when blood, semen, or another bodily fluid from a person infected with the virus enters the body of someone who is not infected. This may be through a puncture in the skin, a shared needle, or the exchange of body fluids.
Infection can happen:
- as an infected mother gives birth
- during sexual activity
- through sharing needles, syringes, or other drug-injection equipment
- through unsafe tattoo techniques
- by sharing personal hygiene items such as razors or toothbrushes
Health workers can be at risk if they are exposed to unsafe medical practices, such as reusing medical equipment, not using personal protection, or incorrect disposal of sharps.
HBV is not spread through food or water, sharing eating utensils, breastfeeding, hugging, kissing, holding hands, coughing, sneezing, or insects that bite.
However, the virus 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
Most infections occur during infancy or childhood. They are rarely diagnosed, as there may be few obvious symptoms.
Symptoms of a new infection may not be apparent in children under 5 years of age and adults with a suppressed immune system. Among those aged 5 years and over, between 30 and 50 percent will show initial signs and symptoms.
These include:
- fever
- joint pain
- fatigue
- nausea
- vomiting
- loss of appetite
- abdominal pain
- dark urine
- clay-colored stools
- jaundice, or a yellowing of the skin and whites of the eyes
Acute symptoms appear from 60 to 120 days after exposure to the virus, and they can last from several weeks to 6 months.
A person with chronic HBV infection may have ongoing episodes of abdominal pain, persistent fatigue, and aching joints.
Tests and diagnosis
A blood test can diagnose acute and chronic HBV infection.
Screening is available for people who have a higher risk of HBV infection or complications due to undiagnosed HBV infection.
These include:
- HBV is transmitted from the mother to the baby
- sex partners of infected persons
- sexually active individuals who engage in unprotected intercourse or have multiple partners
- men who have sex with men
- injection drug users
- people who share a household with someone who has chronic HBV infection
- health care and public safety workers at risk from occupational exposure, for example, to blood or blood-contaminated body fluids
- hemodialysis patients
- anyone receiving chemotherapy for cancer
- anyone coming from a region with a high incidence of HBV, including some Asian countries
- all women during pregnancy
If a woman has HBV during pregnancy, the baby must be vaccinated and receive hepatitis B immune globulin (HBIG) within 12 to 24 hours after birth.
Treatment
There is no specific treatment, cure, or medication for an acute HBV infection. Supportive care will depend on the symptoms.
Treatment for suspected exposure
Anyone who has unprotected exposure to another individual’s potentially infected blood or body fluid can undergo a post-exposure “prophylaxis” protocol.
This consists of HBV vaccination and HBIG given after the exposure and before acute infection develops.
This protocol will not cure an infection that has occurred, but it decreases the rate of acute infection.
Treatment for chronic HBV infection
For chronic HBV infection, the World Health Organization (WHO) recommend treating the individual with an antiviral medication.
This is not a cure, but it can stop the virus from replicating and prevent its progression into advanced liver disease.
A person with chronic HBV infection can develop cirrhosis or liver cancer quickly and without warning. In low-income settings, liver cancer can be fatal within months of diagnosis.
Persons with chronic HBV infection require ongoing medical evaluation and ultrasound of the liver every 6 months to monitor for liver damage or worsening disease.
Prevention
A vaccine against HBV has been available since 1982. This is a series of three injections. The first injection is given soon after birth, the second at least 1 month later, and the third dose is given at least 8 weeks after the second dose.
The CDC recommends that all children receive a birth dose of HBV vaccine and complete the series by 6 to 18 months of age.
Others who should receive the vaccine include:
- children and adolescents not previously vaccinated
- all health care workers
- anyone who may be exposed to blood and blood products through work or treatment
- dialysis patients and recipients of solid organ transplants
- residents and staff of correctional facilities, halfway houses, and community residences
- people who inject drugs
- household and sexual contacts of people with chronic HBV infection
- those with multiple sexual partners
- travelers to countries where HBV is common if they have not been vaccinated
The complete vaccine series induces protective antibody levels in over 95 percent of people vaccinated. Protection lasts for at least 20 years and is usually lifelong.
Other preventive measures
Infection can be prevented by:
- wearing appropriate protective equipment when working in healthcare settings or dealing with medical emergencies
- not sharing needles
- following safe sexual practices
- cleaning any blood spills or dried blood with gloved hands using 1:10 dilution of one part household bleach to 10 parts of water for disinfecting the area
HBV is a significant hazard for health workers around the world, but the vaccine offers effective protection.