Chronic viral hepatitis C (ICD-10 code B18.2) is a persistent liver infection caused by the hepatitis C virus (HCV), a single-stranded RNA virus belonging to the Flaviviridae family. It is a major global health concern, affecting millions worldwide and being a leading cause of liver cirrhosis, hepatocellular carcinoma (HCC), and liver transplantation. While acute HCV infection is often asymptomatic and can resolve spontaneously in a minority of cases, the majority (55-85%) of infected individuals fail to clear the virus and develop chronic infection. This chronic state is characterized by ongoing inflammation and progressive fibrotic damage to the liver. ## Pathophysiology ### The Hepatitis C Virus (HCV) HCV is a highly heterogeneous virus, classified into seven major genotypes (1-7) and numerous subtypes. This genetic variability contributes to challenges in vaccine development and historical differences in treatment response. The virus primarily targets hepatocytes, where it replicates, leading to chronic inflammation and immune-mediated liver injury. The host's immune response, while attempting to clear the virus, also contributes to hepatocyte damage. Persistent viral replication and the chronic inflammatory cascade stimulate hepatic stellate cells, leading to the deposition of extracellular matrix components, a process known as fibrosis. ### Disease Progression The natural history of chronic HCV infection is one of slow but progressive liver damage. Over decades, sustained inflammation and fibrosis can lead to cirrhosis, a severe form of liver scarring characterized by architectural distortion and impaired liver function. Once cirrhosis is established, patients are at significantly increased risk of developing life-threatening complications such as portal hypertension, ascites, variceal bleeding, hepatic encephalopathy, and hepatocellular carcinoma. Furthermore, HCV infection is associated with various extrahepatic manifestations, including cryoglobulinemia, glomerulonephritis, porphyria cutanea tarda, and an increased risk of B-cell non-Hodgkin lymphoma, which are believed to be driven by chronic immune stimulation and viral replication outside the liver. ## Clinical Presentation ### Early Stages Chronic hepatitis C is often referred to as a "silent killer" because most individuals remain asymptomatic for many years, even decades, despite ongoing liver damage. When symptoms do appear in the early chronic phase, they are typically non-specific and mild, such as fatigue, malaise, nausea, loss of appetite, and mild right upper quadrant abdominal discomfort. These vague symptoms are easily overlooked or attributed to other common conditions, leading to delayed diagnosis. ### Advanced Disease Symptoms become more pronounced as the disease progresses to advanced fibrosis or cirrhosis. Patients may present with signs of liver decompensation, including jaundice (yellowing of the skin and eyes), ascites (fluid accumulation in the abdomen), peripheral edema (swelling in the legs), easy bruising or bleeding, and spider angiomas. Hepatic encephalopathy, characterized by confusion, memory problems, and altered consciousness, is a serious complication. Splenomegaly due to portal hypertension can also be observed. Recognition of these signs prompts urgent medical evaluation. ## Diagnostic Criteria ### Screening and Confirmation Diagnosis typically begins with screening for HCV antibodies (anti-HCV) in individuals at risk. A positive antibody test indicates exposure to the virus but does not differentiate between active and resolved infection. Therefore, all positive anti-HCV tests must be confirmed by detecting HCV RNA (qualitative or quantitative PCR) in the blood. The presence of HCV RNA confirms active, chronic infection. HCV genotyping is essential to determine the specific genotype, as this guides treatment selection. ### Assessment of Liver Damage Once chronic infection is confirmed, the extent of liver damage needs to be assessed. This traditionally involved a liver biopsy, but non-invasive methods are now preferred. These include transient elastography (e.g., FibroScan), which measures liver stiffness as a surrogate for fibrosis, and serologic markers like the APRI (AST to Platelet Ratio Index) or FIB-4 index. Standard liver function tests (ALT, AST, bilirubin, albumin, INR) provide information on hepatocyte integrity and synthetic function. Imaging studies such as ultrasound, CT, or MRI are used to monitor for complications of cirrhosis and screen for hepatocellular carcinoma. ## Standard of Care and Treatment The landscape of chronic HCV treatment has been revolutionized by the development of direct-acting antiviral (DAA) agents. These oral medications target specific viral proteins, effectively interrupting the HCV life cycle. DAA regimens, often combinations of two or three drugs, achieve sustained virologic response (SVR), defined as undetectable HCV RNA 12 weeks after completing therapy, in over 95% of patients. SVR is considered a virologic cure and is associated with significant improvements in liver function, regression of fibrosis, and reduction in the risk of liver-related complications, including HCC, especially in non-cirrhotic individuals. Treatment regimens are tailored based on HCV genotype, prior treatment history, degree of liver fibrosis (cirrhosis status), and presence of comorbidities or drug-drug interactions. Patients with advanced fibrosis or cirrhosis require careful monitoring for complications even after achieving SVR, particularly HCC surveillance with regular ultrasound examinations. Lifestyle modifications, such as strict alcohol avoidance and vaccination against hepatitis A and B, are crucial for all HCV-infected individuals. Liver transplantation remains an option for patients with decompensated cirrhosis or HCC who meet specific criteria, often after successful DAA treatment to prevent reinfection of the new liver.