Everything you need to know about hepatitis A
Learn more about what it is, the symptoms and how it's diagnosed.
What is hepatitis A?
Hepatitis A is an acute, short-term disease caused by the hepatitis A virus (HAV). Hepatitis A is commonly transmitted by through food or water which has been contaminated by faeces from someone who is already infected by the virus. This type of hepatitis is most common in countries where the sanitation is poor. As hepatitis A is an acute infection, it usually passes within a few months, but sometimes it can be severe. For this particular viral infection, there is no treatment available other than relieving the symptoms such as itching and nausea. A vaccination against hepatitis A is available for people at a high risk of infection.
What are the symptoms of hepatitis A?
Usually, acute hepatitis often presents no noticeable symptoms, but if symptoms do develop they may include the following:
- Yellowing of the eyes and skin (jaundice)
- Flu-like symptoms
- Pale stools
- Dark urine
- Unexplained weight loss
- Joint and muscle pains
- Abdominal pain
- Loss of appetite
How is hepatitis A diagnosed?
When liver cells are damaged by infection or inflammation they leak their contents into the blood. Liver cells have two enzymes, aspartate transferase (AST) and alanine transferase (ALT) which are present in much higher concentrations than they are in the blood.
When the liver is damaged, a rise in AST and ALT can be detected in the blood. However, this is not very specific because damage to the muscles (e.g. following exercise) can also elevate the levels of AST in the blood. Although an increase in both AST and ALT indicates the liver cells are damaged, this increase alone doesn't explain what the cause of the damage is.
To discover whether the hepatitis A virus is responsible for the liver damage, a blood test looking for antibodies against the virus is required. When presented with a new infection, the body makes immunoglobulin M (IgM) antibodies against the virus - these are the body’s first line of defence. As the immune system learns to combat the virus it produces Immunoglobulin G (IgG) antibodies. Therefore when a blood test is performed, a current viral infection will show elevated IgM levels in the blood, whilst a previous infection will show elevated IgG levels. This approach works for simple illnesses like hepatitis A and E which don’t have the potential to cause long-term infection.