The term Acute Phase can be confusing. This is because it only refers to the 6 month period of time after the virus has first entered your body. It bears no relation to the acuteness of the symptoms or the severity of the disease.
Antibodies to the virus are produced by your immune system when it reacts to the presence of the virus and are detectable in the blood from between 3 to 12 weeks after initial infection. Depending on how long it takes for the virus to take hold in the body, different immune systems will take different amounts of time to create antibodies. This is called the ‘window period’. Because it can take up to 3 months for the antibodies to show up in a blood test, if you suspect you have recently been infected, it is important to wait this long before having a test. If the antibody test is positive you will be offered a PCR or RNA test.
A polymerase chain reaction (PCR) or RNA test detects the presence of the virus itself, rather than the antibodies to it. It may be offered immediately instead of an antibody test if infection is a strong possibility. For instance, it would probably be used in the case of a health care worker getting a needle stick injury. A PCR test can detect the virus sooner than antibodies can be detected, but is not usually the first test given due its higher cost. The sooner a person starts treatment after infection, the greater the chances they have of clearing the virus. If you know you have been exposed to a high level of risk, then it is probably best to ask for a PCR test.
Liver function tests (or LFTs) are a set of blood tests measuring certain proteins and enzymes to see if the liver is performing its various functions correctly. With HCV there is an average incubation period of seven to eight weeks before a rise in liver enzymes levels occurs. As liver cells are damaged by the virus, enzymes leak into the bloodstream. This leads to a rise in specific enzyme levels. However, even in this acute phase there is not necessarily a rise in enzyme levels.
Symptoms during the Acute Phase
During the acute phase most people do not seem to experience any noticeable symptoms. For the 25-35% of people who do, the symptoms are normally vague and non-specific. They can include low-grade fever, fatigue, appetite loss, abdominal pain, nausea and vomiting. About 20% of the people who develop symptoms contract jaundice. This can be seen in the yellowing of the skin and eyes. This is a sign of the liver’s functions being affected as bilirubin (the pigment of bile) begins to build up in the body. Jaundice is a recognised sign of liver problems and may lead to a test for hepatitis C being suggested.
The problem for most people is that they are unaware that they have been infected because of the lack of symptoms. As these symptoms are similar to many other short term infections most people are unlikely to seek medical attention. And even when they do, most doctors will not necessarily suspect or test for hepatitis C.
Spontaneous clearance of the virus during the acute phase
Somewhere between 15% and 30% of people clear the virus spontaneously during the acute phase. This happens when the immune system is able to eliminate all the viral particles in circulation and destroy all the infected cells. Evidence of the infection in the form of antibodies to hepatitis C will remain in the body for several years or possibly forever. Unlike some other viruses these antibodies do not provide protection against further HCV infection.
Contributory factors to clearing hepatitis C during the acute phase
It is not yet known why some people clear the virus while others do not. Some common factors do exist though which seem to increase the chances of clearing it spontaneously:
- The younger a person is at the time of HCV infection, the greater the chances of clearing the virus.
- Women are more likely to clear the virus than men.
- People who develop symptoms during the acute phase seem to have a greater chance of clearing the virus.
- A healthy immune system, particularly the T cell response to the virus, plays an important part.
- Genotype. There is some evidence that people with genotype 3 have a higher chance of clearing the virus than those with genotype 1.
- The amount of the virus transmitted at the time of infection. People who contracted the virus through transfusion generally have a higher viral load. They appear to be at greater risk of developing chronic hepatitis C than people with other sources of infection.
- Genetics. People with certain genetic make-up are more likely to clear the virus.
Does viral clearance mean absolute clearance?
Some recent reports have called into question the traditional understanding of viral clearance. A recent study using ultra-sensitive tests was carried on a group of people who all had spontaneously cleared the virus and maintained an undetectable HCV viral load in the blood with no clinical signs of hepatitis. The tests revealed the presence of HCV RNA in all participants of the study group. The majority also showed signs of active reproduction by the virus. HCV RNA was found in serum (the liquid part of blood without the clotting factors), dendritic cells (specialist cells of the immune system) and in some white blood cells where there were also signs of viral replication. The study is too limited to be conclusive, but it does challenge assumptions that a resolved infection means that HCV has been completely removed from the body.
When does acute hepatitis C become chronic hepatitis C?
The 70% to 85% of individuals who do not achieve spontaneous viral clearance are considered to be in the chronic phase of hepatitis C after six months of infection. This is confirmed when over a six month period HCV RNA viral presence is detectable on at least two occasions
A diagnosis of chronic hepatitis C at this stage means that the time has now passed when spontaneous viral clearance is likely.
Is spontaneous clearance possible in the chronic phase?
Some people do spontaneously clear HCV even after they have had it for many years but it appears to happen infrequently. There has been no proper systematic study so the reasons for it remain unclear.