Hepatitis C can occur as an acute or chronic form of hepatitis. It involves widespread inflammation of the liver. Unlike the other types of viral hepatitis, hepatitis C virus (HCV) presents difficulties for the immune system to overcome.

Hepatitis C is caused by a single strand ribonucleic acid (RNA) virus. Almost any direct or indirect exposure to infected blood can cause transmission of the virus. Although a potential risk factor can be identified in approximately 90 % of persons with HCV infection, the source of infection cannot always be identified. Potential risk factors include: blood or blood product transfusions before 1992; organ transplantation before 1992; hemodialysis; body piercing; tattoos; intravenous (IV) drug use with shared instruments; high-risk sexual behavior (however, the estimated risk of sexual transmission of HCV is monogamous couples is only about 5%); intranasal cocaine use with shared instruments; occupational exposure to contaminated blood or blood products, e.g., percutaneous exposure by combat medics or corpsmen; and communication of mucous membrane cavities through air. Other direct percutaneous exposure to blood includes acupuncture with non-sterile needles and sharing of toothbrushes or shaving razors.

In the U.S. approximately 20% of reported cases of viral hepatitis are due to Hepatitis C. Most people with acute hepatitis C infection are asymptomatic or have minimal symptoms, such as mild intermittent fatigue. They may be unaware of the infection until chronic liver disease develops 10 to 20 years later. The clinically asymptomatic acute disease can become chronic in about 80% of cases. A chronic infection can last for years, and will often result in liver damage. Signs and symptoms of chronic hepatitis C can include fatigue, malaise, nausea, vomiting, anorexia, arthralgia, right upper quadrant pain, jaundice and ascites. The diagnosis of HCV is often an incidental finding in blood tests done for other reasons.

A positive EIA (enzyme immunoassay) or HCV ELISA (enzyme-linked immunosorbent assay) are among the first confirmatory tests for HCV in association with a positive RIBA (recombinant immunoblot assay). These tests contain HCV antigens and detect the presence of antibodies to HCV antigens. A positive HCV antibody test (EIA or ELISA) confirmed by a positive RIBA verifies the diagnosis. RIBA also referred to as "Western blot", should be performed if the EIA or ELISA is positive. The RIBA contains antigens in an immunoblot format, and the antigens are used as supplemental or confirmatory tests. If the RIBA is positive, the diagnosis is chronic hepatitis C. The HCV RNA is the best and most reliable test currently available as of April 2001. It is pending approval by the Food and Drug Administration (FDA). Routine laboratory tests most used are the alanine aminotransferse (ALT) (formerly SGPT), aspartate aminotransferase (AST) (formerly SGOT), alkaline phosphatase and serum bilirubin. Tests that may also be performed include: serum albumin (measures the serum protein produced by the liver) and prothrombin time (PT). In liver disease, the serum gamma globulin level and the serum albumin may be lower than normal and the prothrombin time may be prolonged. Other diagnostic measures may include liver biopsy; ultrasound; computed tomography (CT) scan.

The Food and Drug Administration (FDA) has approved two types of antiviral treatment: interferon alone, termed interferon monotherapy and interferon plus ribavirin, termed combination therapy. Combination therapy is now the standard treatment for persons who have never received interferon therapy. Treatment may last approximately a year.

In 85% of all HCV cases, the infection will last a lifetime. This puts an affected person at risk for developing cirrhosis (scarring) of the liver, liver cancer, and even death. Severe adverse side effects of the drugs used in treatment may include: flu-like symptoms (severe at onset and decreasing over time); thyroid abnormalities; impaired concentration; depression and other mood changes which may be severe; anemia (when ribavirin is used); patchy hair loss (alopecia); insomnia; skin rash; abnormal fetal development in pregnancy; and cardiorespiratory complaints. Some of the aforementioned side effects may be temporary, but may be significantly disabling for a considerable period of time. Autoimmune disorders and auditory changes may also occur as side effects of drugs. Other disorders that may occur include eye problems; seizures; renal disease and worsening of diabetes mellitus. Combination therapy suppresses, but does not kill the virus, and relapses after treatment are common. Occasionally, active hepatitis C will respond to treatment to the extent that the RNA test becomes negative and the person becomes asymptomatic. However, the HCV remains dormant in the system and may flare later.

• May be entitled to special monthly compensation where the Veteran has a single service-connected disability rated as 100% with additional service-connected disability or disabilities independently ratable at 60% or more, which are separate and distinct from the 100% service-connected disability and involves different anatomical segments or bodily systems. See  38 CFR 3.350(i)(1) – Special Monthly Compensation (SMC).

• Service connection for hepatitis requires blood serology testing to establish a diagnosis and identify the type of hepatitis present.  Liver function tests (LFTs) are necessary to assess the severity of the disease.

• Consider service connection on the basis of long term health effects potentially associated with infectious diseases under 38 CFR 3.317(d) when applicable

• Evaluate sequelae, such as cirrhosis or malignancy of the liver, under an appropriate diagnostic code, but do not use the same signs and symptoms as the basis for evaluation under DC 7354 and under a diagnostic code for sequelae. (See 38 CFR 4.14.).

• For purposes of evaluating conditions under diagnostic code 7354, “incapacitating episode” means a period of acute signs and symptoms severe enough to require bed rest and treatment by a physician.

• For purposes of evaluating conditions in 38 CFR 4.114, the term “substantial weight loss” means a loss of greater than 20 percent of the individual's baseline weight, sustained for three months or longer; and the term “minor weight loss” means a weight loss of 10 to 20 percent of the individual's baseline weight, sustained for three months or longer. The term “inability to gain weight” means that there has been substantial weight loss with inability to regain it despite appropriate therapy. “Baseline weight” means the average weight for the two-year-period preceding onset of the disease. [38 CFR 4.112]