Hepatitis C
Each year about 30,000 new cases of hepatitis C occur. It is the most common blood-borne infection in the country. Until blood screening began in 1990, the primary mode of known transmission was through transfusions. It is also transmitted through contaminated needles and possibly through sexual transmission. The cause of transmission is unknown in 40% of cases.
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About 4 million Americans have had an initial HCV infection and an estimated 2.7 million are currently chronically infected. Hepatitis C also affects 170 million people worldwide. Most people with chronic HCV, however, are unaware that they have it and experts believe that over the next 20 years, there will be a fourfold increase in diagnosed cases in the US. It is currently not possible to predict which patients will develop the chronic form of hepatitis C.
Ethnic Groups. In general, HCV occurs most commonly in non-Caucasian men between the ages of 30 and 49 years. Over 6% of African Americans are infected with HCV, which is about two to three times the risk for Caucasians.
Other High-Risk Groups. Some other specific groups are at higher than normal risk:
- Intravenous drug users. Intravenous drug use has been the greatest risk factor for HCV since the early 1980s. It accounts for 60% of new cases and 20% to 50% of chronic infections. Individuals who engage in this activity have a risk for infection that is between 50% and 80%. Intravenous drug use, particularly in people who also drink alcohol heavily, poses a higher risk for severe complications. Intranasal cocaine use also increases the danger. Needle exchange and educational programs have reduced the risk for HIV transmission and should have similar benefits for preventing HCV.
- People who had transfusions before 1992. Although transfused blood has been tested for both hepatitis B and C since the early nineties, individuals given transfusions before then, even decades before, may still be at risk. Such individuals are urged to be tested. Hepatitis C can exist for decades without symptoms, and nearly 300,000 people who had transfusions before 1992, including many who were children at the time, may have been infected. Of some reassurance was a 1999 study of people who had transfusions when they were children. After an average of 20 years, only 8% tested positive for hepatitis C and only three people showed signs of any liver abnormalities. These results suggest that the virus may be less aggressive in children than adults, but further observations are needed to learn if the infection remains mild beyond age 30.
- Among the homeless and people in prison the HCV prevalence may be as high as 40%.
- Infants of infected mothers. The risk for transmission to an infant during pregnancy is about 2% but increases to 4% to 7% during delivery. The highest rates of infection (20%) are in mothers who are also HIV positive. It is not clear if Cesarean section delivery in infected mothers offers protection. Avoiding fetal scalp monitoring and prolonged labor may reduce the risk. (Breastfeeding does not increase the risk.)
- Organ transplant recipients.
- Sexual transmission. Although HCV can be transmitted sexually, the risk is much less than with hepatitis B or other sexually transmitted diseases. For example, the risk for transmitting the HCV within a monogamous relationship is only about 2% to 3%. The risk is 4% to 6% for partners of people who have high-risk sex (e.g., those with multiple partners or sex workers). Of note, the risk for women becoming infected through sexual transmission may be three times that of men.
- Hospital workers. It should be strongly noted that health care providers in general are at very low risk. The risk of infection from a needle stick is now believed to be about 2%. (It is not yet clear if this poses any significant risk to patients.)
- Children who survive cancer.
- Possibly people who have had body piercing or tattoos with contaminated equipment.
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