Hepatitis B is a serious liver infection caused by the hepatitis B virus (HBV). Although most people exposed to the virus recover completely, chronic infections can lead to severe liver damage, cirrhosis (scarring of the liver), liver cancer and death.

How is hepatitis B transmitted?
Hepatitis B virus is spread by contact with body fluids of an infected person. These body fluids include blood, semen, vaginal secretions, and saliva. In about 30-40% of cases, the means of transmission is not known.

What is the risk of hepatitis B?
There are approximately 140,000-320,000 new cases of hepatitis B infection each year in the United States. About 90-95% of adults recover from hepatitis B in a few months, clearing the virus from their systems and developing immunity. They will never get hepatitis B again: however, blood tests will always show that they were once infected, and blood centers will not accept donated blood from these individuals. Up to 10% of young adults who get the disease become carriers – as many as 1.25 million Americans are hepatitis B carriers. Carriers are people who have the virus in their blood and can infect others, even though they do not feel sick and have no obvious signs or symptoms of hepatitis B.

People infected with hepatitis B who are unable to clear the infection from their bodies in six months are chronically infected with hepatitis B. The younger the person when infected, the greater the risk that the disease will become chronic. Chronic hepatitis B means that the virus is in the blood, infecting liver cells and possibly damaging them. Chronic hepatitis B can lead to cirrhosis, primary liver cancer, liver failure and/or death. An estimated 5,000 people die each year of chronic liver disease associated with HBV infection.

People who are exposed to blood or body fluids of an infected person are at risk. You may also be at risk if you:

• Are exposed to bodily secretions, including on the job – as first aid or emergency workers, firefighters, funeral directors, police personnel, dentists, and dental assistants, and medical personnel
   
• Live in the same household with an infected person
   
• Have sex with a carrier of chronically infected person or have more than one sexual partner
   
• Inject illicit drugs
   
• Received a blood transfusion prior to 1975 (when a test to screen blood was developed) or if you have received multiple transfusions of blood or blood products
   
• Have hemophilia
   
• Work or are a patient in a health care or long-term care facility
   
• Work or are incarcerated in a prison
   
• Are bitten so that the skin is broken by someone whose saliva contains the virus
   
• Travel to countries with a high incidence of hepatitis B
   
• Are a hemodialysis patient

How is hepatitis B diagnosed?
The most common symptoms of hepatitis B occur within 25-180 days following exposure and include loss of appetite, nausea and vomiting, fever, weakness or tiredness lasting weeks or even months, abdominal pain in the area of the liver (upper right quadrant), dark urine and light-colored stool, joint pain, and yellowing skin and eyes (jaundice).

An estimated 40% of people infected with hepatitis B have no recognizable signs or symptoms and do not know how or when they became infected. The only way the disease can be positively identified is through a blood test. Many people are surprised to learn when they donate blood that they have tested positive for hepatitis B. Hepatitis blood tests are not usually included in the routine blood tests of a physical examination.

The blood tests for hepatitis B may include anti-HBs (surface antibody test), HBsAg (surface antigen test), and anti-HBc (core antibody test). Although anti-HBs and anti-HBc may be found in the blood of individuals who are immune to hepatitis B, the presence of HBsAg indicates infection with the hepatitis B virus. In addition, patients with levels of HBV in their blood may test positive for HBeAg (e antigen) or HBV DNA.

How is hepatitis B treated?
There is no known cure. You can protect yourself against hepatitis B with a vaccine. For full protection, three injections are required. Adults and adolescents should receive the second injection a month after the first. The third dose, considered a booster, is given six months later. Hemodialysis patients and other who are immunocompromised (those taking immunosuppressive drugs or who are infected with HIV) may require larger doses of the vaccine.

Vaccination is recommended by the Centers for Disease Control and Prevention (CDC) for the following groups of people:

• All newborns, infants and children, especially sexually active teenagers
   
• Health care and emergency personnel
   
• Hemodialysis patients
   
• Patients with chronic liver disease
   
• Military personnel
   
• Morticians and embalmers
   
• Patients and staff at institutions for the mentally challenged
   
• Prison inmates
   
• People with multiple sexual partners
   
• Injection drug users
   
• Sexual partners and household members of HBV carriers
   
• International travelers
   
• Members of ethnic or racial groups with a high rate of HBV infection (including African Americans, Latino Americans, Native Americans, Alaskan Natives, and Asian and Pacific Islanders)