Hepatitis Virus B

Many persons infected with hepatitis B virus (HBV) have no signs or symptoms and thus do not realize they have an infectious disease that can be transmitted to others. As a result, the threat of HBV infection to susceptible health care workers and other persons is still a very serious health problem, despite the fact that the numbers of new hepatitis B cases have been declining in recent years in the United States.

Epidemiology
Worldwide, an estimated 350 to 400 million persons are believed to have chronic (long-standing) hepatitis B. In the United States alone, an estimated 1.25 million persons are infected with HBV and are capable of infecting other persons.

High-risk groups. Although it is important to remember that many low-risk persons can become infected, no risk factor can be identified for many reported acute (self-limited) hepatitis B cases. However, in a recent year, when a definite risk factor was known, cases fell into the following CDC categories:

1. More than one sex partner: 550 cases.
2. Illegal injection drug use: 364 cases.
3. Sexual or household contact with a hepatitis B patient: 208 cases.
4. Male homosexual activity: 181 cases.
5. Surgery: 146 cases.
6. Needlestick or other skin injury: 69 cases.
7. Hemodialysis or blood transfusion: 18 cases.
8. Medical employee with blood contact, other than surgical, needlestick, or skin injuries: 11 cases.

Deaths. Worldwide, more than 520,000 people die as a result of chronic hepatitis B each year. In the United States alone, an estimated 5,000 persons die each year from chronic liver disease caused by hepatitis B.

Conversely, the number of U.S. deaths caused by acute hepatitis B is relatively low. Deaths reported to be due to acute hepatitis B currently number about 35, and the majority of the victims are age 40 or older.

HBV Transmission
High HBV concentrations have been found in blood, blood products, and body fluids containing visible blood (e.g., bloody saliva, bloody respiratory secretions, and menstrual fluids). HBV has also been found in bile, feces, cerebrospinal fluid, and synovial fluid, but usually in low concentrations.

Transmission via injections or cuts. Because blood contains the highest HBV concentrations, it is the most common substance in which the virus is transmitted in health care settings. Needlesticks and other sharp implement injuries can allow HBV-containing substances to be injected or absorbed into the skin. In clinical settings, these injuries most often occur during the use of hollow-bore needles filled with blood, but other types of sharps are involved as well.

A small cut or break in the skin, a dermatitis, or even a hangnail can also provide an opening for HBV infection. Health care workers should wear gloves whenever they might touch any patient body substance, except sweat. For dental professionals, the primary source of HBV infection is bloody saliva.

HBV is still often transmitted by use of contaminated needles during illegal injection drug use. The virus can also enter the blood when people nick themselves with a borrowed HBV-contaminated razor, experience gum bleeding while using a borrowed HBV-contaminated toothbrush, or undergo ear piercing, tattooing, or acupuncture with HBV-contaminated instruments.

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