A HOSPITAL issued an alert yesterday over fears that patients could have been exposed to tuberculosis.

Doctors at Bishop Auckland General Hospital, in County Durham, have written to 89 patients who shared a ward with someone with the infectious form of TB.

But they stress that the chance that the disease has been passed on is low.

The patients, who were on the same ward as the infectious patient before the disease was diagnosed, are being told it is very unlikely they would contract the disease.

However, a smaller number, thought to be more vulnerable because of other health problems, are to be offered chest x-rays to check for the illness.

The patients have been told to contact their doctor if they develop a persistent cough, lose weight or are worried about any other symptoms.

Hospital officials stress that even in the event of someone developing TB, treatment with antibiotics is available. The course of treatment would take six months.

Dr John Sloss, a consultant microbiologist at County Durham and Darlington Acute Hospitals NHS Trust said: "We have identified those people who are most likely to have been in contact with the infected patient.

"Tuberculosis is quite difficult to pass on, even in these circumstances, so we do not believe that there is any need for them to be unduly concerned.

"However, we think it is appropriate that they are all given advice on how to spot signs of the disease - and that some of them are offered precautionary x-rays."

Because of rules over patient confidentiality, officials cannot reveal details of the patient whose illness sparked the scare.

Although the disease is increasing in the UK, it remains quite rare.

Last year, there were fewer than 7,000 cases - with about 40 per cent of all cases in the London area.

In 2003, there were 148 cases of TB in the North-East. Last year, the figure rose to 153.

Many cases involve elderly patients who contracted TB as children.

The illness can lie dormant for decades before becoming active.

People with active TB in their lungs can infect others by coughing, sneezing or even talking close to others.

The Health Protection Agency said that the very elderly and those with immune systems weakened by other medical conditions were more susceptible to the disease.

However, most people who get TB have had a prolonged exposure, usually from someone in the same household.

The microscopic tubercle bacillus - also known as Myobacterium tuberculosis - can be carried by tiny droplets of mucus and saliva, which can be inhaled by other people.

In 1993 the World Health Organisation declared TB to be a global emergency, with a third of the world's population infected with TB, and two million dying each year from the disease.

Most areas of the country have an immunisation programme in schools to protect children from exposure.