And many people may already be infected without knowing.

Dr John Dillon, consultant liver expert at Ninewells hospital in Dundee, told the seminar on the virus, that the disease had been called "the real Millennium bug".

"You could also describe it as an iceberg disease because we don't know the extent of the problem, and you can't talk about icebergs without thinking of the Titanic," he said.

US death rate could triple

Hepatitis C was only discovered nine years ago, but is already thought to have caused the death of up to 10,000 people in the USA.

But experts believe that the number is set to triple over the next 10 to 15 years.

No reliable information exists in Britain about the numbers of people infected, but estimates suggest at least 250,000 have the disease.

According to the World Health Organisation, at least 100 million people around the world are thought to be infected.

Fatigue

Most do not know they have the virus, as they can carry it for 20 years or more with few symptoms other than fatigue and minor aches and pains. The symptoms do not tend to be incapacitating, but can decrease sufferers' quality of life.

Scientists are seeking a vaccine

Some complain of being turned away by their doctors who say they are depressed or stressed.

Hepatitis C attacks the liver and is already the main cause of liver transplantation and liver cancer in the West. Up to 80% of sufferers are thought to end up developping chronic liver disease.

There is no vaccine against it and the treatment that exists only works for one in five people. Latest research suggests treatment combining interferon and ribavirin can stamp out the disease, but only if the virus is caught early.

Body fluids

With an estimated 50.8 million sufferers, China has the highest number of cases, followed by Egypt, Vietnam and the USA. Britain ranks ninth in the world league.

The virus is transmitted mainly by blood to blood contact, but, like HIV, can also be passed on through sexual intercourse and, in rare cases, in breast milk and saliva.

The main high risk activity is needle sharing. At least 90% of injecting drug users in many big cities are thought to be infected.