Hepatitis A

How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?

How is it used?
There are two types of test, both of which detect antibodies. Antibodies are produced by the body to protect it against antigens (foreign proteins). IgM (immunoglobulin M) is the first antibody the body produces after exposure to a virus and is used to show that an infection has just begun. IgM against HAV is measured in patients with obvious signs of acute hepatitis, such as jaundice, dark urine, pale stools, fever and loss of appetite. IgG (immunoglobulin G) antibodies develop later and last for many years, protecting the person against further infection with the same virus. A positive total antibody test (which detects both IgM and IgG) suggests either a recent or a past HAV infection, and is also positive after vaccination against HAV.

When is it requested?
The test for hepatitis A IgM antibodies is carried out when there are specific symptoms or when exposure to the virus is likely. When vaccination against hepatitis A is being considered, it may make sense to check whether it is needed (the presence of antibodies makes vaccination unnecessary). After the first two doses of vaccine, measuring total antibodies (IgG and IgM) against the hepatitis A virus shows the response to the vaccine.

What does the test result mean?
If the test result is positive (or reactive) without previous vaccination, there has been a past infection, even if you were not aware of it. About 30% of adults over 40 have antibodies to the hepatitis A virus. If you have been vaccinated, on the other hand, a positive test shows immunity to the hepatitis A virus, and you are no longer at risk of being infected.

Is there anything else I should know?
Infection with the hepatitis A virus is thought to give lifelong immunity against further infection.

1. How could I have been infected without knowing it?
2. Is there any way to prevent the disease?

1. How could I have been infected without knowing it?
The virus can be found in contaminated water and in faeces. You may have eaten raw fruit or vegetables handled by an infected person who did not wash their hands thoroughly, or raw or undercooked shellfish from contaminated water. Children often catch hepatitis A without showing any symptoms, or with mild symptoms such as fever or diarrhoea that are often mistaken for flu.

2. Is there any way to prevent the disease?
Yes. A vaccine is available and is recommended for travellers to developing countries, for children living in areas where the disease is common and for people with other forms of liver disease