By a Newsnet reporter
The likely source of the outbreak of Legionnaires’ disease that has hit an area of Edinburgh is thought to be outdoors, possibly nearby cooling towers.
The latest developments came as it emerged the number of suspected cases rose to forty, of these one patient has died, two have been released and a further twelve are in intensive care.
Further cases are likely, with the weekend expected to see the numbers peak, thereafter experts expect the numbers to decrease.
Speaking at a press conference this afternoon, Health Secretary Nicola Sturgeon confirmed that the source of the outbreak appeared to be outdoors and said:
“No link has been identified between patients other than a general association with the affected area in the south west of Edinburgh.
“What that does is underline the view that the source of this infection is an outdoor community source and not an indoor specific source such as the case if was a spa in a hotel.”
Cooling towers can generate quite a bit of spray according to Legionella control expert Denis Kelly.
Mr Kelly, a senior consultant with Legionella Control International, explained that pinpointing the source could take some time and warned that even after investigation and tests it might not be possible to determine the source with absolute certainty.
“It can be quite difficult particularly if there are a large number of possible sources in one given geographical area.
“I understand that there are something like fourteen or more cooling towers implicated in this outbreak so far.”
Mr Kelly explained that anywhere that generated water spray could spread the disease, but that the number of cases that have thus far came to light suggested the source was likely to be “tower based”.
Dr Duncan McCormick, chair of NHS Lothian’s incident management team said that although there could be no confirmation until tests had concluded, the team were hopeful that the source may already have been decontaminated.
Dr McCormick explained that the water coolers implicated in the outbreak had been treated in order to kill off the microbes and that although the number of cases was expected to increase, this was due to the incubation period of the disease with some people having aleady been infected but yet to develop symptoms.
He said: “The incubation period of Legionnaires’ disease is between two and 14 days but the average is five or six days, so we’re expecting to have more cases over the next few days.
“But if our evidence and reaction have been correct, we hope to have removed the source through our shock treatment of these cooling towers.
“We’d hope that by the weekend – five or six days after the treatment, we’ll start to see a decline in cases.”
Dr McCormick insisted that there was no threat to the public water supply and that the disease cannot be contracted by drinking water.
“The public water supply in Edinburgh is extremely closely monitored and in addition it’s not possible to contract Legionnaires’ Disease through drinking water.” he said, and added:
“It’s contracted through the inhalation of water vapour in the form of an aerosol and that doesn’t happen through drinking water supplies.”
The Health Secretary added:
“The fact remains that the risk to the general public is low – however, due to the incubation period of the infection we are still expecting to see an increase in cases over the next couple of days.
“There is a now a dedicated advice line for everyone who is affected by the outbreak and households in affected areas will receive a leaflet advising on the symptoms to look out for.
“A tremendous amount of work has been done to identify and deal with the source of infection and ongoing work is focusing on cooling towers in the area. All of the towers have been treated and the first phase of site inspections has now been completed by HSE.”
According to the BBC, tests have been carried out at four sites, they include the cooling towers at:
- North British Distillery, Wheatfield Road, Gorgie
- McFarlan Smith (pharmaceuticals), Wheatfield Road, Gorgie
- Aegon (insurance), where towers are used to cool servers, in Lochside Crescent, South Gyle
- Burtons Foods, Bankhead Place, Sighthill
An emergency information leaflet will be delivered to all homes and businesses in affected areas tomorrow. GPs have also been provided with information on spotting the signs of infection.
A dedicated NHS helpline has been set up for anyone concerned and can be reached on 0800 0858 531.