What is Viral Hepatitis?
Hepatitis describes inflammation of the liver. This inflammation can arise from various causes, including exposure to certain chemicals, excessive alcohol consumption, specific genetic conditions, or an overactive immune system. However, a common cause of hepatitis is viral infection, leading to what is known as viral hepatitis.
The liver performs numerous functions for overall health. These functions include detoxifying harmful substances, processing nutrients from food, and producing bile essential for digestion. When the liver becomes inflamed due to a viral infection, its ability to perform these functions is compromised, potentially leading to significant health complications.
The Viruses: Key Differences
While both Hepatitis B (HBV) and Hepatitis C (HCV) are viruses that primarily target the liver, they belong to different viral families, which dictates fundamental differences in their biological makeup and how they replicate. HBV is a DNA virus, classified within the Hepadnaviridae family. Its genetic material integrates into the host cell’s DNA during replication.
In contrast, HCV is an RNA virus, belonging to the Flaviviridae family. Its genetic material replicates entirely within the host cell’s cytoplasm without integrating into the host’s genome. This distinction influences how each virus interacts with the host’s immune system and also affects the development of antiviral treatments and vaccines.
How Hepatitis B and C Spread
Hepatitis B and C viruses primarily transmit through contact with infected blood or other body fluids, but there are important distinctions in their common modes of spread. HBV can spread through blood, semen, and other body fluids, making sexual contact a significant route of transmission. This includes unprotected sexual activity. Additionally, sharing needles or syringes for drug injection and mother-to-child transmission during childbirth are common ways HBV spreads.
HCV is predominantly transmitted through direct blood-to-blood contact. The most common cause of HCV transmission in many regions is sharing needles or other drug injection equipment. While sexual transmission of HCV is possible, it is considerably less common than for HBV. Other potential routes for HCV include exposure to unsterilized equipment for tattoos or piercings, or sharing personal items like razors or toothbrushes that may have come into contact with infected blood.
Disease Course and Liver Impact
The progression and long-term effects of Hepatitis B and C infections on the liver differ significantly, particularly regarding the likelihood of developing chronic disease. When adults are infected with HBV, most experience an acute infection that resolves spontaneously, with only about 5-10% developing chronic hepatitis B. However, the risk of chronicity is much higher for infants infected at birth, with over 90% developing chronic infection.
Conversely, a high percentage of individuals infected with HCV develop a chronic infection. Most people with acute hepatitis C do not clear the virus naturally, leading to a persistent infection that can continue to damage the liver over time. Both chronic HBV and HCV infections can lead to serious liver conditions such as cirrhosis, which is severe scarring of the liver, liver failure, and hepatocellular carcinoma, a type of liver cancer. Chronic hepatitis B is a leading cause of liver cancer worldwide, accounting for a significant proportion of cases.
Treatment Options and Prevention
Approaches to treating and preventing Hepatitis B and C vary due to the distinct characteristics of each virus. For Hepatitis B, a highly effective vaccine exists, providing strong protection against infection. This vaccine is recommended for all infants at birth and for adults at higher risk of infection, significantly reducing the global burden of chronic HBV and its associated complications, including liver cancer. For individuals with chronic hepatitis B, lifelong antiviral medications are available to manage the virus, suppress its replication, and reduce the risk of liver damage and cancer, though these medications do not typically cure the infection.
In contrast, there is currently no vaccine available for Hepatitis C. However, advancements in treatment have transformed the outlook for HCV infection. Modern direct-acting antiviral (DAA) medications can cure over 90% of chronic HCV infections, often within a short course of treatment, typically 8 to 12 weeks. These oral medications directly target the virus, interfering with its ability to replicate. Prevention of HCV primarily relies on avoiding contact with infected blood, including safe injection practices and screening of blood products.