Legionellosis – UK (04): (Scotland) More cases, fatal
A ProMED-mail post, http://www.promedmail.org, ProMED-mail is a program of the International Society for Infectious Diseases http://www.isid.org
Date: Wed 6 Jun 2012
Source: BBC News Edinburgh, Fife & East Scotland http://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-18337813
Health officials have said the number of confirmed and suspected cases of legionnaires' disease in Edinburgh has risen to 40. Of these, one person has died, 12 remain in intensive care, and 2 others have been discharged from hospital.
NHS [National Health Service] Lothian has said it could take until the weekend before the extent of the outbreak is known. Health secretary Nicola Sturgeon said the suspected source was environmental contamination. She said early indications suggested the outbreak was the result of a contaminated cloud being emitted from a cooling tower in the south west of the city. Officials are now liaising with the Met Office to analyse the impact of temperature and wind speed on plumes from the towers.
So far in the outbreak there have been a total of 21 confirmed and 19 suspected cases. Dr Duncan McCormick, chair of NHS Lothian's incident management team, said the majority of those affected were men aged between their mid 30s and late 80s.
Although the number of suspected cases has risen, he said the numbers in intensive care had decreased. Ms Sturgeon described the outbreak as a "significant event" for NHS Lothian and said the government had activated their emergency plan. She said they expected to see a decline in the number of cases in the next 5 to 6 days as 16 cooling towers in the city had been treated with chemicals to kill the bacteria. However, Dr McCormick said, although they were "confident" they had identified the source, because of its incubation period, more cases of legionnaires' disease were expected. The Scottish government said they would be issuing information leaflets in the affected area of Edinburgh.
The BBC understands that tests have been carried out at 4 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; and Burtons Foods, Bankhead Place, Sighthill.
Dr McCormick told BBC Scotland he expected instances of the disease to peak in the coming days. He said: "The incubation period of legionnaires' disease is between 2 and 14 days but the average is 5 or 6 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 -- 5 or 6 days after the treatment, we'll start to see a decline in cases."
The 16 towers were identified as a potential source of the outbreak following the 1st reported case on Thursday last week [31 May 2012].They were chemically treated on Sunday night and Monday morning [2-3 Jun 2012].
Dr McCormick said that people living in the Gorgie, Dalry, and Saughton areas were generally at low risk. He added: "I want to give that reassuring message. However, people who fall into certain risk groups, these are males who are adults, who have an alcohol, drinking habit, and have an underlying illness such as diabetes, heart disease, or lung disease -- these people are at greater risk. These people should be very much aware that if they start feeling symptoms of flu-like illness, together with diarrhoea, cough, and confusion, they should be consulting their GP or NHS 24 as soon as possible."
Dr McCormick said there was no threat to the city's public water supply. He added: "The public water supply in Edinburgh is extremely closely monitored and in addition it's not possible to contract legionnaires' disease through drinking water. It's contracted through the inhalation of water vapour in the form of an aerosol and that doesn't happen through drinking water supplies." Martin Donaghy, the medical director of Health Protection Scotland, said the information so far suggested the outbreak contained the most common strain of the disease.
[The number of confirmed and suspected cases of legionnaires' disease in Edinburgh has increased dramatically from 6 to 21 and 4 to 19, respectively since the 1st ProMED-mail post 2 days ago (Legionellosis - UK (02): (Scotland) 20120605.1156972); there is still only one death from this disease. For a discussion of legionnaires' disease, see ProMED-mail post Legionellosis - UK (02): (Scotland) 20120605.1156972.
The news report above says that 16 cooling towers were identified as a potential source of the outbreak and were chemically treated about 3 days ago. However, even if this remediation were effective, cases exposed before the remediation could continue to occur because the incubation period for this disease is 2 to 10 days.
The news report also says that the "most common strain of the disease"
has been implicated, perhaps referring to Legionella pneumophila serogroup 1. However, the news report has so far not indicated if genotyping has been done of the clinical or any environmental isolates. Genotyping of patient and environmental isolates has become a helpful tool to establish transmission pathways. The predominance of one genotype of legionella isolated from patient specimens would suggest transmission from a common source. Because legionella may be found in environmental samples without linkage to any cases of legionellosis, the actual causative infectious reservoir can be confirmed by matching the genotype of clinical and environmental isolates (see http://www.ncbi.nlm.nih.gov/pmc/articles/PMC86783/ and http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2730281/). However, clinical isolates are often not available because the diagnosis of legionnaires' disease is commonly made on the basis of serology or the legionella urinary antigen test, and not culture of patient specimens.
Lothian is a region of the Scottish Lowlands that includes Edinburgh City. For a map of this region, see http://en.wikipedia.org/wiki/Lothian. Saughton is a suburb to the west of Edinburgh. Dalry and Gorgie are to the immediate east of Saughton close to the center of Edinburgh (http://en.wikipedia.org/wiki/Dalry,_Edinburgh). For a map showing Saughton, Dalry, and Gorgie, see http://www.maplandia.com/united-kingdom/scotland/scotland/city-of-edinburgh/gorgie/.
Scotland can be located in the interactive HealthMap/ProMED-mail map at http://healthmap.org/r/2wlL.
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