INVESTIGATORS are still unable to pinpoint the source of the city’s legionnaires’ outbreak, despite receiving the results of key tests.
The results have pinpointed industrial sites on Gorgie’s Wheatfield Road as the “most likely” source of the outbreak.
The incident management team (IMT) formed to track down the source of the deadly infection has concluded that the “cluster of cooling towers” located in the street were believed to be responsible.
Despite concluding that the airborne exposure of the disease probably started on May 23, tests have so far been unable to confirm the presence of the bacteria in any of the samples taken from the towers. Further analysis of the samples is ongoing.
Two of the firms at the centre of the outbreak, chemical firm Macfarlan Smith and North British Distillery, are on Wheatfield Road.
Both companies, who were criticised over their cleaning regimes, issued statements saying that they had confidence in the anti-infection work carried out at their sites.
NHS Lothian said yesterday that the most common type of legionella bacterium, legionella pneumophila serogroup1, has been identified as the cause of infection.
The number of confirmed cases now stands at 47, with 46 suspected. Two people have died, while one person is now being treated in intensive care.
Dr Duncan McCormick, IMT chairman, said: “Evidence to date is pointing to an airborne exposure to legionella in the south-west of Edinburgh starting around Wednesday, May 23. The IMT took immediate action on June 3, when a cluster of cases was identified, to ensure cooling towers in the area were treated with high doses of chemical disinfectant.
“Our investigation into the outbreak is ongoing and it is reassuring that the number of people who have been confirmed as having legionnaires’ disease has slowed over the past week.”
A spokeswoman for Macfarlan Smith said: “We note that after extensive testing, there is no microbiological evidence to positively confirm the presence of legionella bacteria in any of the samples taken from any of the potential sources.
“We took samples immediately after the Environmental Health Department took their samples on June 3 and these have been independently tested. These tests show no presence of legionella bacteria.”
The spokeswoman added that routine samples tested weekly from each of the cooling units have shown “no abnormal levels of bacterial growth before or during the outbreak”.
Macfarlan Smith shut down one of its seven cooling towers after the Health and Safety Executive served an improvement notice and demanded “thorough cleaning” and better access for inspection and maintenance.
A North British Distillery spokesman said that independent tests of its three cooling towers had returned “all-clear” results. He added: “Throughout this difficult period we have remained confident in our health and safety procedures relating to the cleaning and testing of our cooling towers. All of our cooling towers are continuously monitored and dosed.”
Health Secretary Nicola Sturgeon said: “This investigation is continuing but the progress made to date is encouraging.”