Hepatitis C and Other Forms of Hepatitis
Approximately 20%–40% of acute viral hepatitis cases reported in the United States are of the non-A, non-B type; of this group, most cases are caused by the hepatitis C virus (HCV). The prevalence of chronic HCV infection in the United States is 3.5 million individuals; the worldwide prevalence is approximately 71 million individuals. Risk factors for the transmission of HCV include parenteral drug use, hemodialysis, occupational exposure to HCV-infected blood, blood transfusion or organ transplant prior to 1992, receiving clotting factor concentrates prior to 1987, and incarceration. Persons born between 1945 and 1965 have the highest incidence of hepatitis C infection. Although the role of sexual activity in the transmission of HCV remains to be fully elucidated, this mode is not a predominant source of transmission.
Of all the hepatitis viruses, HCV causes the most damage in immunocompetent hosts because of direct hepatocyte cytotoxicity. It may cause cirrhosis, fulminant hepatitis, and hepatocellular carcinoma. At present, hepatitis C is the most common cause of liver cancer and the most common indication for liver transplantation in the United States.
A sensitive enzyme immunoassay has been developed for the detection and quantification of total HCV core antigen in anti-HCV-positive or anti-HCV-negative sera. In addition, a 1-step PCR assay is available to detect HCV RNA and provide HCV genotyping.
Treatment of acute HCV infection with interferon-α2a reduces the rate of acute infections converting to chronic HCV infections. Spontaneous resolution of acute HCV infection may occur in up to 50% of patients. Ledipasvir/sofosbuvir has demonstrated a 94%–99% sustained virologic response in patients with or without prior treatment, with or without cirrhosis, and with prior liver transplant.
Other hepatitis viruses include:
Hepatitis D: causes chronic delta hepatitis, a severe form of chronic liver disease. Interferon-α2a and lamivudine have been found to be beneficial in treating chronic hepatitis D infection.
Hepatitis E: causes sporadic as well as epidemic acute viral hepatitis and is prevalent in many developing countries. In patients with preexisting chronic liver disease, acute hepatitis E infection has a protracted course, with high morbidity and mortality.
Hepatitis G: often occurs as a coinfection with hepatitis B virus or HCV, but it usually does not increase their pathogenicity.
virus (TTV): identified in a small percentage of patients with posttransfusion hepatitis. TTV has been implicated as a potential cause of 30%–50% of cases of lymphoma and Hodgkin disease.
American Association for the Study of Liver Diseases; Infectious Diseases Society of America (AASLD-IDSA). HCV Guidance: recommendations for testing, managing, and treating hepatitis C. www.hcvguidelines.org. Updated May 24, 2018. Accessed February 22, 2019.
European Association for the Study of the Liver. EASL Recommendations on treatment of hepatitis C 2016. J Hepatol. 2017;66(1):153–194.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.