Those who are unable to clear the hepatitis C virus (HCV) on their own after 6 months – 70-85% of people who contract HCV – will progress to the chronic phase. Chronic hepatitis C is a long-term infection, and it is diagnosed when HCV is still detectable, on at least two occasions, over a 6 month period of time.
Is spontaneous clearance possible in the chronic phase?
When someone is diagnosed with chronic HCV, it means their immune system was unable to fight the virus on its own during the first 6 months of infection – the acute phase – and it’s highly unlikely a person will clear the infection on their own without treatment. Although a small percentage of people clear the virus spontaneously, this happens so infrequently with chronic HCV that additional research is needed to discern how and why this happens to those who have already had the infection for over 6 months.
Disease Progression in the Chronic Phase
After someone is diagnosed with chronic HCV, disease progression can vary significantly from person to person. On average, it takes around 20 years for scarring and severe damage of the liver (cirrhosis) to develop, but some may experience cirrhosis in less than 10 years.
While it’s important to monitor one’s progression through viral load, liver enzyme, and genotype tests, rate of progression cannot be determined by tests alone. Extensive scarring of the liver is fairly likely when someone is diagnosed with chronic hepatitis C, but the rate at which cirrhosis develops is different for everyone with HCV. Some notice signs and symptoms of cirrhosis within 10 years, and for others, it takes 50 years or more before cirrhosis occurs. Those who progress to cirrhosis slowly commonly die of other, unrelated conditions, illnesses, and diseases.
Symptoms during the Chronic Phase
As disease progression varies from person to person, so does the number and magnitude of the symptoms experienced by each person with HCV. Some people notice signs and symptoms of infection during the first 6 months – the acute phase – and others will experience few, if any symptoms for upwards of 20 years.
While HCV is known to cause damage to the liver via inflammation, scarring, and cirrhosis, it’s recently become known that the hepatitis C virus can also affect other functions and organs in the body – namely, blood cells, brain function, circulatory, and the immune system. This means that some people will experience little to no signs and symptoms while others will notice systemic symptoms throughout the body as the disease progresses.
Presently, it’s believed that both the hepatitis C infection and the immune system’s response to HCV affect the cells in the liver causing death of healthy liver cells, inflammation in the liver, scarring, and an enlargement of the liver. When the liver is enlarged from inflammation, the fibro elastic sheath surrounding the liver is stretched, and that swelling can trigger pain and sensitivity in the abdomen. Enlargement of the liver (hepatomegaly) occurs in over 60% of people who have chronic HCV.
A healthy functioning liver contains a group of cells called stellate (star-shaped) cells that regulate the flow of blood through the liver while also storing vitamin A and helping the body break down fat. The inflammation caused by the presence of chronic hepatitis C triggers reactions to occur in stellate cells, and it alters their function by causing them to dispense vitamin A. These reactions begin the process that leads to fibrosis – a condition caused by the body’s response to liver damage.
The body responds to infected and inflamed liver cells by releasing chemical signals (cytokines) activating white blood cells to travel to the liver and the area of infection and inflammation. White blood cells from outside the liver pair with specialized white blood cells to neutralize and remove harmful viruses, bacteria, parasites, or tumors inside the liver. The activity from the white blood cells produces additional chemical signals that cause stellate cells to produce collagen fibers (scar tissue) between cells.
When the body produces scar tissue, it is trying to reduce the spread of infection to other cells and areas of the body. When this process functions properly, the infection, inflammation, and injury is fixed, and the scar tissue is eventually dissolved back into the body. In the liver, stellate cells that were activated by infection, inflammation, or injury to produce collagen fibers die, and the scar tissue returns back to normal, healthy liver tissue.
With chronic hepatitis C, the builds up of scar tissue around the liver cells is too fast, and the body cannot properly dissolve the stellate cells and the collagen fibers. That buildup of scar tissue around liver cells is called fibrosis. Built up scar tissue then causes additional inflammation, triggering more stellate cells and collagen production, and fibrosis worsens – eventually leading to cirrhosis.
Free Radicals and Fibrosis
Another consideration when looking at the triggers of fibrosis is free radicals. Free radicals are the highly reactive by-product of a cell’s normal reaction when performing activities such as breaking down fats or producing energy. When someone is healthy, cells can protect themselves from these chemical substances. In chronic HCV, reparative cell activities generate too many free radicals at once, such as during the triggering of stellate cells to produce collagen fibers, and the free radicals produced are left to cause additional cell and tissue damage. Individuals with chronic hepatitis C can be affected by free radicals for a number of reasons:
- Over-production of free radicals in the liver can be caused by chronic inflammation.
- When free radicals attack, injure, and eventually kill cells, they can chemically alter fat in liver cells, and the body’s natural response to the additional cell damage will lead to more fibrosis.
- Free radicals can interact with other chemicals in the liver, and when liver function is impaired, there can be an overload of chemical reactions that can cause further damage to cells and lead to extensive fibrosis and later, cirrhosis.
Why can’t the liver repair itself with chronic HCV?
When someone is diagnosed with chronic HCV, the infection causes cell damage, inflammation caused by combatting the infection causes cell damage, then scarring occurs, which leads to fibrosis, and fibrosis continues to cause repetitive injury. Even though the liver is capable of healing itself – even when a substantial area is affected – with chronic HCV, it cannot keep up, as it does not have the time and space to heal before the injury/inflammation/cell repair cycle repeats itself.