The acute phase

The term Acute Phase can be confusing, because it only refers to a 6 month period of time after the virus has entered your body. It bears no relation to acuteness of symptoms, or severity of disease.

After the virus has entered your body there are three tests that will show or suggest its presence, HCV Antibodies, PCR and liver function tests (LFTs).

Antibodies to the virus can start to be detectable in the blood between 3-12 weeks after infection. Different peoples immune systems take different lengths of time to create antibodies, depending on the amount of time it takes for the virus to take hold in the body. This is called the window period. Because it can take 3 months or more for the antibodies to show up in a blood test, it is important to wait this long before having an antibody test if you suspect you have recently been infected.

A polymerase chain reaction (PCR) test may be given if infection is a strong possibility for instance in the case of a health care worker getting a needlestick injury. A PCR test becomes positive sooner than the antibody test but is not usually the first test given as it is more expensive. However the sooner a person starts treatment after infection the higher the chances they have of clearing the virus so if you know you have been exposed to a high level of risk then ask for a PCR test.

There is an average incubation period of seven to eight weeks before there may be a rise in liver enzymes levels. Liver function tests or LFTs are a set of blood tests measuring specific proteins and enzymes to see how well the liver is performing its various functions. As liver cells are damaged by the virus, enzymes leak into the bloodstream leading to a rise of specific enzyme levels. However, there is not necessarily a rise in enzyme levels even in this acute phase.

Most people do not seem to experience symptoms during the acute phase. For the 25-35% of people who do experience symptoms they 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 which is the yellowing of the skin and the whites of the eyes. This is a sign of the livers function being compromised as bilirubin (the pigment of bile) builds up in the body. Jaundice is a recognised sign of liver problems and as such it 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 this lack of symptoms or vagueness of them.

As these symptoms are similar to many other short term infections most people are unlikely to seek medical attention. Even if they do, most doctors will not suspect or test for hepatitis C.

Somewhere between 15% and 30% of people clear the virus completely during the acute phase. This is the spontaneous clearing of HCV by the immune system through elimination of all viral particles in circulation and destruction all infected cells. Evidence of this infection in the form of antibodies to hepatitis C will possibly always remain in the body, but they will definitely remain for at least for some years. Unlike some other diseases these antibodies do not provide immunity against a further HCV infection at a later date.

It is not clear exactly why some people clear the virus while others do not, but some common factors are known:

a) The younger a person is at the time of HCV infection, the more chance they have of clearing the virus
b) Women are more likely to clear the virus than men.
c) People who develop symptoms during the acute phase seem to have a greater chance of clearing the virus.
d) A healthy immune system particularly the T cell response to the virus plays an important part
e) Low alcohol consumption
f) Genotype. There is some evidence that people with genotype 3 have a higher chance of clearing the virus than those with genotype 1.
g) The amount of virus transmitted at the time of infection. People who contracted the virus through transfusion and so have a higher viral load appear to be at greater risk of developing chronic hepatitis C than people with some other sources of infection.
h) Genetics. People with certain genetic make up are more likely to clear the virus.

Some recent reports, however, have called into question the traditional understanding of viral clearance. A recent study using ultra-sensitive tests was carried out amongst a group of people who had spontaneously cleared the virus and had maintained 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, with the majority showing 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 challenges assumptions that resolved infections really do mean the complete eradication of HCV from the body.

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 HCV antibody testing is positive and HCV RNA viral presence is detectable on at least two occasions over a six month period.

So a diagnosis of chronic hepatitis C at this stage means you have passed the time when spontaneous viral clearance is likely or possible.