What is Hepatitis C?
Hepatitis C, a viral disease that destroys liver cells, is the most common blood-borne infection in the United States. Approximately 36,000 new cases of acute hepatitis C infection occur each year in the United States, according to the Centers for Disease Control and Prevention (CDC) in Atlanta. People with acute HCV infection may exhibit such symptoms as jaundice, abdominal pain, loss of appetite, nausea, and diarrhea. However, most infected people exhibit mild or no symptoms.
About 85 percent of people with acute hepatitis C develop a chronic infection. Chronic hepatitis is an insidious disease whose barely discernible symptoms can mask progressive injury to liver cells over 2 to 4 decades. An estimated 4 million Americans are infected with chronic hepatitis C, according to CDC.
Chronic hepatitis C often leads to cirrhosis of the liver and liver cancer and causes between 8,000 and 10,000 deaths a year in the United States. It is now the leading cause of liver cancer in this country and results in more liver transplants than any other disease.
How Is HCV Transmitted?
People become infected with the hepatitis C virus (HCV) through direct contact with an infected person's blood. Although this contact can occur in a number of ways, injection drug use now accounts for at least 60 percent of HCV transmission in the United States, according to CDC. This estimate may be conservative because about 10 percent of people newly diagnosed with HCV do not report an identifiable risk factor. Some of these cases may represent people who are reluctant to identify injection drug use as a risk factor. Because HCV is highly transmissible through the blood, anyone who has ever injected drugs is at risk for liver disease and should be tested for the virus.
Injecting drug users (IDUs) contract hepatitis C by sharing contaminated needles and other drug injection paraphernalia. One recent study found that 64.7 percent of IDUs who had been injecting for 1 year or less were already infected with the virus. Overall prevalence of HCV was 76.5 percent among IDUs who had been injecting drugs for 6 years or less.
Additional research indicates that rates of hepatitis C among past or current IDUs are extremely high in a number of cities in the United States. For example, last year a NIDA- and CDC-funded study detected HCV infection in approximately 85 percent of 3,000 IDUs in Seattle. Researchers in Texas reported similar percentages in several Texas cities and noted that many recovering IDUs who tested positive for HCV reportedly had not injected for 5 to 15 years.
Hepatitis C, HIV/AIDS, and hepatitis B share common risk factors for infection. IDUs have a high prevalence of co-infection with the viruses that cause these diseases. It is important to test IDUs for all three viruses.
Prior to the development of sophisticated HCV blood screening tests in the early 1990s, blood transfusions accounted for a substantial proportion of HCV infections. Now, there is only 1 chance in 100,000 that someone will get HCV from transfused blood or blood products. However, people who received blood transfusions prior to July 1992 should be tested for HCV.
The risk of perinatal transmission of hepatitis C is relatively low. About 5 of every 100 infants born to HCV-infected women become infected. However, about 17 out of every 100 infants born to HCV-infected women who are also infected with HIV become infected with HCV. HCV infection among women with HIV also is associated with increased maternal-infant transmission of HIV.
Can HCV Infection Be Prevented?
Although there are vaccines for other forms of hepatitis, none exists to protect against HCV. However, prevention of illegal drug injection would eliminate the greatest risk factor for HCV infection in the United States, according to CDC. Therefore, drug addiction treatment can play a major role in reducing HCV transmission. Research shows that drug users who enter and remain in treatment reduce high-risk activities, such as sharing needles and other drug injection paraphernalia, that are responsible for spreading HCV. AIDS outreach and HIV prevention programs for out-of-treatment drug users that reduce HIV risk also reduce the risk of HCV transmission.
How Can HCV Infection Be Treated?
Available antiviral drugs to eliminate the virus and reduce liver injury are not highly effective for patients with chronic hepatitis C. Side effects can be severe and the treatment is costly, lengthy, and effective for only 30 to 40 percent of those with the disease.
For More Information
Patients and health care providers can obtain information on hepatitis C from the Centers for Disease Control and Prevention, Hepatitis Branch: Mailstop G-37, 1600 Clifton Road, NE, Atlanta, GA 30333, 1-888-443-7232. CDC's hepatitis World Wide Web site at www.cdc.gov/ncidod/diseases/hepatitis contains a variety of educational materials on HCV and links to additional sources of information.