THE cause of an outbreak of Legionnaires' disease in south London is being sought after four people contracted the deadly illness.

Health inspectors are now combing the borough and other parts of south London for sites where the infection may have started.

The first case was identified at Lewisham Hospital on July 18 and the last was admitted on August 15.

Since then the Government's Health Protection Agency (HPA) has inspected and ruled out a number of unnamed sites in its bid to track down the source.

The potentially fatal form of pneumonia is often found in air conditioning cooling towers and hot and cold water systems in factories, hotels and hospitals.

The HPA would not reveal exactly which sites it had tested or how many are being investigated.

But one suspected source, a train wash at South East Trains' depot at Grove Park, was ruled out last week.

The agency has also confirmed it is examining possible sites infected patients may have visited and is looking for a common link.

Leisure centres can be sources for the disease but the council carries out routine checks for the bug every four weeks.

Eric Bittle, 46, of Hoser Avenue, Grove Park, was the first patient diagnosed with the disease on July 18.

He spent four weeks in intensive care and is still in a high dependency unit.

His wife Barbara says he was an hour from death when the ambulance arrived to take him to hospital.

She said: "I could tell something was wrong. His breathing was awful the morning he was rushed to hospital.

"He looked grey and his lips were blue. Eric was taken into intensive care where they tried to sort out his breathing."

She added: "For 23 days he was on a ventilator. Now he is in a stable and comfortable condition.

"He has had a small tracheotomy to help him breathe. We don't know when he will be coming out."

Two victims have been discharged from hospital but Mr Bittle and one other are still being treated.

South East London Health Protection Unit (HPU) is working with environmental health officers from Lewisham Council and the HPA.

So far it has held four "incident" meetings to co-ordinate efforts to track down the infection.

Dr Rachel Heathcock, HPU director and consultant in communicable disease control, said: "It is important to remember Legionnaires' disease can not be spread from person to person and there is no risk of the infection being passed onto other hospital patients."

The facts

Legionnaires' disease is a rare form of pneumonia, which is also called Legionellosis.

It is generally contracted by inhaling mists from water sources such as whirlpool baths and cooling towers, which have become infected with the bacteria.

The most common cause of the disease is contaminated air conditioning systems.

It cannot be passed from one person to another.

Legionnaires' disease has an incubation period of between two to 10 days.

The first symptoms are similar to flu with headaches, muscle pain, high fever, the chills, nausea, vomiting and diarrhoea.

Legionnaires' disease has a high fatality rate of about five to 15 per cent.

Those with chronic diseases such as diabetes, cancer or serious kidney problems are extremely vulnerable if they catch the disease.