Since vaccination against hepatitis C does not exist, the only other choice for prevention is to avoid exposure to the virus.
Chris Miller, PhD
Viral hepatitis is a liver disease that can be caused by several viruses (hepatitis A, B, C, D, E, and G viruses). Even though all of the hepatitis viruses cause similar damage to the liver, the viruses themselves are all different, including the characteristics of the diseases caused. For example, only hepatitis A and E are commonly acquired by ingesting contaminated food or water, with the virus being shed in the feces of an infected person. Thus, hepatitis A and E are referred to as having a "fecal-oral" mode of transmission. Hepatitis B, C, D, and G are transmitted by percutaneous (through the skin) or permucosal (through mucous membranes) contact with contaminated blood or other body fluids. Thus, hepatitis B, C, D, and G viruses are referred to as being "bloodborne" viruses.
The bloodborne forms of hepatitis have varying degrees of risk for developing chronic hepatitis, while there is no risk of chronic hepatitis with type A or E. Currently, vaccines available to the public exist only for type A and B hepatitis. The vaccine for type A does not protect against any other type of hepatitis. The vaccine for type B, taken by most health-care workers, does give protection against co-infection with type B and D, but gives no protection against types A, C, E, or G. Thus, dental workers who have received a hepatitis B (or A) vaccination series are still susceptible to the bloodborne disease hepatitis C.
Incidence and prevalence of hepatitis C
The CDC indicates that there are about 36,000 new hepatitis C infections a year in the United States, compared with at least 140,000 new annual cases of hepatitis B. While there are fewer new cases of type C than type B, there is a much greater risk of developing chronic (long-term) hepatitis with type C. In fact, 80-85 percent of those infected with type C will retain the virus in their bodies for the rest of their lives, and 70 percent will have chronic liver damage. In comparison, 5-10 percent of those infected with hepatitis B will develop chronic infections. It is estimated that 3.9 million (1.8 percent) Americans have been infected with hepatitis C, of whom 2.7 million are chronically infected. Treatment of hepatitis C is effective in only 10-40 percent of cases, and this disease causes 8,000 to 10,000 deaths a year in the U.S. from chronic liver damage.
The virus frequently establishes a long-term infection because it apparently changes during the course of the disease and the antibodies that are produced early in the infection become ineffective against the changed virus. So the virus evades the body`s defense mechanisms and can induce progressive liver damage. These viral changes are also why there have been difficulties in developing a vaccine. A standard vaccine is directed toward a specific form of the virus. When the virus changes during the course of the disease, the antibodies induced by vaccination are no longer effective.
Most new cases of hepatitis C are due to high-risk, drug-abuse behaviors. Risk groups for hepatitis C include:
Y Drug users who inject
Y Hemodialysis patients
Y Health-care workers
Y Sex contacts of infected persons
Y Persons with multiple sex partners
Y Recipients of transfusions before 1992
Y Recipients of blood-clotting factors made before 1987
Y Infants born to infected mothers (about five of every 100 infants born to infected mothers become infected).
Hepatitis C in health-care workers
Health-care workers who have a risk of exposure to human-body fluids are at risk for hepatitis C infection. A review of studies on health-care workers exposed to hepatitis C-infected blood through sharps injuries showed that from 0 to 7 percent became infected as suggested by the presence of antibody to hepatitis C. This review also mentioned that two cases of hepatitis C transmission from a blood splash to the eye have been reported. Studies on determining the number of dental workers with evidence of exposure to hepatitis C suggest that the prevalence is similar to that of the general population (1-2 percent).
Since vaccination against hepatitis C does not exist, the only other choice for prevention is to avoid exposure. Even though the risk to dental workers appears to be very low, this disease does have high rates of chronic infection and is associated with limited treatment success. These concerns make hepatitis C a disease worthy of concern. Thus, for the hygienist, prevention includes handling contaminated sharp instruments very carefully and using appropriate barriers such as gloves, mask, and protective eyewear routinely with all patients.
References available upon request.
Chris Miller, PhD, is professor of oral microbiology and executive associate dean at the Indiana University School of Dentistry.