Hundreds of patients put on alert after it emerged a hospital worker was carrying the potentially-fatal hepatitis C virus have been cleared.

More than 280 people were screened after it was revealed an employee at the Royal Sussex County Hospital in Brighton had the virus.

Test results have revealed none of the patients has been infected.

But 170 people have so far failed to respond to letters explaining about the potential risk of infection, which were sent by the Brighton hospital to 527 patients. A further 66 were sent out by the Sussex Nuffield Hospital in Brighton.

The employee is based in the Royal Sussex' orthopaedics and trauma unit and had previously worked at the Nuffield.

About 350 patients responded to the letters with more than 280 agreeing to come in for tests.

Some patients chose not to be screened or went to their GP instead.

Staff are now double checking the remaining patients who did not respond to make sure they received the original letter. The patients contacted were treated by the worker between January 2000 and the beginning of this year.

The employee involved in the scare did not know of the virus until it was discovered in a routine blood test. Hospital bosses were immediately informed.

The employee is receiving treatment and continues to work but is no longer carrying out procedures that could expose patients to the virus.

A hospital spokesman said: "We have said all along the risk of infection is very small but it was important to be absolutely certain."

Hepatitis C has been recognised since 1989 but it is only recently tests to diagnose the virus have become available.

Transmission rates in the general population for hepatitis C are low and the incubation period is between two weeks and six months.

The virus may cause inflammation of the liver. Most people infected do not realise they have the illness and suffer no symptoms.

Some can become carriers of the virus and have an increased lifetime risk of liver disease.