Anita Roddick the founder of the Body Shop has revealed she is suffering from the disease Hepatitis C.
Dame Roddick who is 64, says she contracted the virus through a blood transfusion while giving birth to her youngest daughter, Sam, in 1971.
She is also suffering from cirrhosis of the liver which is one of the long-term effects of the disease.
The environmental campaigner says she had no idea she had virus which was discovered recently during routine blood tests.
Although those infected with Hepatitis C often show no symptoms initially, the long-term effects can include liver damage and cancer.
The virus which is transmitted by infected body fluids is twice as likely to affect men than women and is often called the "silent killer".
People who share needles are particularly at risk but unprotected sex as well as sharing toothbrushes and razors are also risk factors.
A routine blood screening programme for the disease was introduced in the UK in 1991 and although no vaccine exists to prevent Hepatitis C infection, there are treatments available which are effective in more than 50% of cases.
According to the Health Protection Agency (HPA) the number of adults infected with Hepatitis C in England was around 231,000 in 2003 but they estimate that the number of people living with serious liver disease caused by the virus could more than double by 2015.
An estimated 4,855 people were living with cirrhosis of the liver or serious liver failure in 2005 and that figure is expected to rise to 10,090 by 2015.
Dame Anita has joined the campaign to raise awareness of Hepatitis C and to demand more government action and funding and has become Patron of the UK's Hepatitis C Trust, a charity set up in 2001 by a group of people who have the disease.
The virus causes inflammation of the liver and over time limits the important function the liver plays in keeping the body healthy.
Research has also revealed that Hepatitis C causes damage to other parts of the body, such as the digestive system, the immune system, the brain and the lymphatic system.
There are two stages with Hepatitis C infections; the acute infection which is the first 6 months after initial infection, and the chronic infection.
During the acute phase very few symptoms appear and about 20 per cent of people who become infected appear to shed the virus and do not go on to have chronic infection.
It can be decades before people discover the disease and as a rule a diagnosis is complicated because common symptoms such as fatigue, depression, insomnia, stomach pains and upsets, skin irritations and rashes, are very often attributed to other causes.
It is estimated that some 200 million people all over the world have Hepatitis C.