I am writing in response to the letter from the reader who was naturally worried about the reported cases of legionnaires disease across south-east London, and who was concerned that the source(s) of the disease had not been found.

I would like to advise on the current position of the investigation in Bexley, which has at times involved eight environmental health staff from Bexley investigating potential sources.

It is often extremely difficult to identify the source of legionella incidents and these investigations could be described as like looking for a needle in a haystack.

The investigation has involved Lewisham, Wandsworth, Bexley and other boroughs.

Of the 12 reported cases, one involves a Bexley resident and two cases have had links with Bexley.

Bexley sampled all the cooling towers with a potential link to these incidents the day after we were notified. All these test results were negative. However, as a precautionary measure, all the sampled systems have been subject to a further thorough clean and disinfection.

Further investigations have also taken place at other less likely sites.

Whilst the reader refers to a single source for these incidents, it is possible that with cases across south-east London there is more than one source.

Legionella bacteria occur naturally in the environment and incidents of the disease increase during the hotter summer months. The Health Protection Agency have advised that there is a possibility that we are simply seeing an increase in the detection of single cases, in line with the national picture, and this would therefore not constitute an outbreak.

I would like to reassure Bexley residents that legionnaires disease cannot be spread from person to person, and that if any common sources are found immediate action will be taken to protect public health.

Councillor Joel Briant, cabinet member for the environment, Bexley Council