Hepatitis C: The Silent Killer
Hepatitis C (HCV) is often referred to as “the silent killer” or “the silent epidemic.” It affects an estimated 3.2 million Americans — more people in the United States than any other form of hepatitis — but because there are so few symptoms, many of those infected go undiagnosed.
Despite decades of research and the development of successful screening tests, a successful vaccine for HCV has evaded scientists. In the United States, four times as many people are infected with HCV than HIV and because of the long asymptomatic incubation period of the disease, it is among the fastest growing blood borne diseases. It is estimated between 20,000 and 50,000 people become infected each year and close to 10,000 die each year of HCV-related liver disease.
Hepatitis C is one of five identified variants of hepatitis. There are also A, B, D and E.
Hepatitis A and B were recognized by the medical community for decades, with vaccines developed in 1995 and 1981, respectively. Although the appearance of hepatitis B decreased tremendously in the blood supply during the mid-1970s, Dr. Harvey J. Alter of the NIH discovered that a new strand of hepatitis was spreading rapidly. Originally labeled “non-A, non-B hepatitis” it was diagnosed through a process of exclusion. Despite a decade of research, it took until 1987 for scientists to isolate and identify the hepatitis C virus. A routine screening test was developed in 1992.
There are two main forms of hepatitis C, acute and chronic. Acute hepatitis C virus infection is a short-term illness that occurs within the first 6 months after someone is exposed to the hepatitis C virus. For most people, acute infection leads to chronic infection. Despite being asymptomatic, over a period of twenty to thirty years, chronic hepatitis C is a serious disease than can result in long-term health problems, or even death. People with chronic hepatitis C suffer from liver disease, cirrhosis or fibrosis of the liver, and are at an increased risk for liver cancer.
While there is no cure, combination therapy with pegylated interferon and Ribavirin is commonly used with a new generation of drugs expected by 2012. Like most other medications, there are some side effects to these medications that have led many to claim the treatment is more painful than the disease itself. The treatment is not universally effective, however. While testing is ongoing, there is currently no vaccine or cure for hepatitis C.
For patients suffering with serious liver disease as a result of HCV infection liver transplant is an option. While it does not eliminate HCV from the body, it does “start the clock anew” for the transplanted, undamaged liver.
In the case of hemophiliacs who receive a liver transplant, a new liver means the patient is cured of hemophilia. (Factor 8 and 9 is manufactured in the liver. A new liver from a donor unaffected by hemophilia will produce factor proteins thereby curing hemophilia.) However, given the complexity of liver transplantation including the risk of rejection, immune suppression, and the shortage of suitable livers for donation, transplantation is not viewed as an acceptable means of curing hemophilia.
Viral Inactivation of Hepatitis C
Hepatitis C is different from A and B in that it is very resistant to heat treatment. Subsequently, even when pharmaceutical companies began heat-treating plasma-derived factor products to successfully prevent HIV transmission, HCV was still present and infected many. It is estimated that 90% of hemophiliacs who used clotting factor before 1988 were infected with hepatitis C.
In 1980, Dr. Edward Shanbrom developed a detergent-solvent process he claimed destroyed the lipid envelope, or outer shell of viruses, which would then kill and eliminate viruses from the blood supply. (Click to see original patent) Dr. Shanbrom offered his process to all of the companies manufacturing factor at that time. Each of the companies declined the patent. By 1984, the four major factor manufacturers were relying on heat treatment to virally inactivate factor products. At same time the companies were in the process of developing recombinant or synthetic products that did not use human blood plasma and were therefore not at risk for transmitting blood borne diseases.
By 1992, all of the drug companies manufacturing factor had adopted a detergent-based cleaning process much like Dr. Shanbrom’s proposed in 1980 that safely removed both HIV and HCV from blood products. As a result, hemophiliacs using blood products from 1984 to 1992, when factor products were largely free of HIV, continued to be exposed to hepatitis C. Among those infected were children newly diagnosed with hemophilia between 1984 and 1992. So while theirs is a generation of hemophiliacs unaffected by HIV, they continue to live with the serious consequences of HCV infection.
With the development of hepatitis C screening tests in 1992 and the widespread use of detergent-based cleaning processes similar to the one developed by Dr. Shanbrom in 1980, the occurrence of hepatitis C in the hemophilia community has dropped to almost zero. All plasma-based factor concentrates are now treated with these processes.
While infection with either HIV or hepatitis C is tragic, the co-infection of the hemophilia community during the 1980s with both viruses was catastrophic. When HIV develops into AIDS, the human immune system is weakened dramatically. As a consequence of their weakened immune system, it was soon realized that in co-infected hemophiliacs deterioration of the liver began almost immediately. Medications to treat HIV/AIDS further taxed the liver. The death rate from HCV infection among hemophiliacs rose dramatically.
For years those co-infected with HIV and hepatitis C were kept off liver transplant lists and out of liver transplantation trials because many in the medical community felt that AIDS would eventually kill these patients and a scarce resource such as donor livers should be used in healthier patients. Policies have since changed and hemophiliacs co-infected with HIV and HCV are now eligible for liver transplantation.
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Brettler, Doreen, Harvey Alter, Jules Dienstag, Ann Forsberg, and Peter Levine. “Prevalence of hepatitis C antibody found in a cohort of hemophilia patients.” Blood. 1 Jul. 1990. p. 254-256.
CDC – Division of Viral Hepatitis. www.cdc.gov/hepatitis/
“Hepatitis A Vaccine Information.” National Network for Immunization Information. http://www.immunizationinfo.org/vaccineInfo/vaccine_detail.cfv?id=3#historydata
“Hepatitis B Vaccine History.” Hepatitis B Foundation. http://www.google.com/search?hl=en&q=Hepatitis+B+vaccine+history
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“Myths and Facts About Hepatitis C.” www.Pegasys.com
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