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Microsoft word - interim report - 22 july 2013 .doc

2013 INTERIM REPORT TO NHS LOTHIAN BOARD
LEGIONNAIRES' DISEASE OUTBREAK JUNE 2012
SUMMARY OF RESULTS OF EPIDEMIOLOGICAL AND
MICROBIOLOGICAL INVESTIGATION
Executive Summary
This is the second interim report of the Edinburgh Legionnaires' outbreak in June 2012. It focuses on the investigations carried out, impact on NHS Lothian and recommendations from the Incident Management Team. Investigation of the outbreak involved epidemiological and microbiological analysis, temporal and spatial modelling of patient and weather data and environmental sampling and analysis of potential water sources for Legionella organisms. The outbreak largely affected a defined population in south west Edinburgh. It had considerable impact on NHS services during June 2012. Over 1000 patients were investigated and treated in primary care. Forty-five of the confirmed cases were admitted to acute hospitals in NHS Lothian. Twenty-two patients required admission to Critical Care; 19 were admitted to Intensive Care and three to a High Dependency Unit. In total, 92 cases were identified in the outbreak; 56 confirmed cases and 36 probable and possible cases. Seven of the confirmed cases and two in the probable and possible category were identified outwith NHS Lothian. Four deaths have been reported among formally confirmed cases. The case fatality rate was 7.1% among confirmed cases and 4.3% among all cases. The proportion of patients presenting with severe disease, including altered mental state was higher than that reported in other recent UK or European outbreaks. Follow up epidemiological investigations including seroprevalence and case-control studies are still being analysed. This report contains preliminary findings. As the science in this area is evolving, this has enabled further investigations that use new techniques involving whole genome DNA sequencing. These are currently being undertaken to generate information that might help provide more information about when and where individual patients acquired the disease. The final outcomes of these studies will inform further public health action and help us continue to improve the management of future outbreaks. We will share our findings across Scotland and internationally. Health and Safety enforcing authorities are investigating the circumstances of the deaths under the direction of the Crown Office and Procurator Fiscal Service Health and Safety Division. A multi-agency debrief held soon after the outbreak highlighted staff commitment and coordination as important lessons to be disseminated. Areas for improvement included revision of guidance, review of resources and facilities to be made available rapidly and for the duration of the outbreak, additional training and exercising of joint agency plans and additional means of communicating to the public. This was a large outbreak of Legionnaires' disease affecting the population of south west Edinburgh and caused considerable impact on NHS services during June 2012. A coordinated response and prompt action by Public Health, Primary Care, Acute Services, Environmental Health, and Lothian Unscheduled Care Services (LUCS) resulted in less morbidity and fewer deaths than in previous outbreaks of similar size. 1. Introduction

This is the second interim report of the Edinburgh Legionnaires' disease outbreak in June 2012. It focuses on the epidemiological and microbiological investigation, impact on NHS Lothian and recommendations from the Incident Management Team. Health and Safety enforcing authorities investigating the circumstances of the deaths under the direction of the Crown Office and Procurator Fiscal Service Health and Safety Division. This means that there are some limitations to the level of detail that can be disclosed at this time.
2. Epidemiological investigation

Timely and accurate epidemiological information is vital for providing evidence to inform outbreak control measures and monitoring the impact of these measures. The purpose of the epidemiological investigation was to determine the number and distribution of cases and identify any potential sources of the outbreak.
2.1 Objectives of the epidemiological investigation:

 To describe the epidemiology of the outbreak, with respect to people,  To generate hypotheses for testing potential source(s) of exposure and the effectiveness of remedial action  To test these hypotheses The epidemiological investigation was undertaken jointly by NHS Lothian, Health Protection Scotland, the Health Protection Agency and the Meteorological Office. The collection and processing of epidemiological data was undertaken by the NHS Lothian Health Protection Team with support from Health Protection Scotland for data management and analyses. Specialised temporal and spatial modelling support, provision of meteorological data and modelling was provided by the Bioterrorism and Emerging Disease Analysis, Microbial Risk Assessment Emergency Response Department, Health Protection Agency, Public Health England, Porton Down and the Meteorological Office respectively. Potential cases outwith Lothian were interviewed by the relevant Health Boards' Health Protection Teams (for cases within Scotland) or the Health Protection Agency, Public Health England (for potential cases that had returned to England). Key steps undertaken in the epidemiological investigation included:  Descriptive epidemiology to determine the clinical and case status, age/sex, spatial distribution and dates of onset of illness.  Analytical epidemiology to determine the association between cases and their likely exposure to the organism. This was carried out in the first instance by modelling of wind directions and speeds over the affected area and in-depth analysis of diaries that cases completed describing their movements.  Follow up analytical epidemiological studies to examine the frequency and severity of illness in the community and the differences between those who became unwell and those who did not.
2.2 Methods of descriptive and analytic epidemiology and modelling

2.2.1 Case ascertainment

 Cases identified within NHS Lothian
Cases identified within NHS Lothian were reported to the Health Protection Team by clinicians in primary care or from local hospitals. Reported cases were line-listed and shared with Microbiology on a daily basis and updated as required.  Cases outwith NHS Lothian
During the course of the investigation a number of cases and potential cases were reported who were resident outwith NHS Lothian or were residents of NHS Lothian who became ill whilst outwith Lothian and were subsequently treated outwith Lothian. Details of such cases were reported to Health Protection Scotland by the relevant Health Protection Team in Scotland or via the Health Protection Agency for cases outwith Scotland. Health Protection Scotland established and maintained a line listing for cases outwith NHS Lothian. This was updated daily and shared with NHS Lothian Health Protection Team so that the master line listing was kept up to date. Trawling questionnaires were developed to generate hypotheses about the potential source of infection. These questionnaires were completed by the relevant Health Protection Team and emailed or faxed securely to Health Protection Scotland, who incorporated them into the trawling questionnaire database and sent a copy of the questionnaire to the Lothian Health Protection Team.  Case definitions
The following case definitions are based on European Centre for Disease Control definitions which were agreed by the Incident Management Team to be used in this outbreak. Confirmed Case An individual with clinical or radiological evidence of community acquired pneumonia, microbiologically confirmed Legionella pneumophila by either a positive Legionella pneumophila culture, Legionella pneumophila Sg1 urinary antigen test or fourfold rise in specific serum antibody, disease onset on or after 14 May 2012 and who has links to south west Edinburgh. Probable Case An individual with clinical or radiological evidence of community acquired pneumonia, a positive Legionella pneumophila Polymerase Chain Reaction (PCR) on respiratory secretions, disease onset on or after 14 May 2012 and who has links to south west Edinburgh. Possible Case An individual with clinical or radiological evidence of community acquired pneumonia, disease onset on or after 14 May 2012 and who has links to south west Edinburgh.
2.2.2 Line Listings
A line listing of all cases of Legionnaires' disease was maintained by NHS Lothian Health Protection Team using a password protected spreadsheet on the secure server. This line listing contained basic demographic details of all cases, case status (confirmed, probable, possible), laboratory results, hospitalisation status and ward, some details of symptoms, occupation and whether the case had a history of exposure to south west Edinburgh. The line listing was updated on a daily basis and shared with Health Protection Scotland for the production of epidemic curves throughout the outbreak investigation. Not all data items were initially available for all cases. Prior to data from the trawling questionnaires becoming available an anonymised extract from the line listing was shared with the Microbial Risk Assessment Emergency Response Group at Porton Down for the generation of preliminary spatial models.
2.2.3 Interviews
A member of NHS Lothian Health Protection Team (or other nurses co-opted into the investigation) conducted detailed interviews and completed a trawling questionnaire with each case, or with a family member of any cases who were too ill to be interviewed. The trawling questionnaire had been developed by Health Protection Scotland for use in an earlier outbreak of Legionnaires' disease. This questionnaire captured information on demographics, onset, symptoms, hospitalisation, underlying medical conditions, occupation, work location(s), usual mode of transport and route to work, exposures to potential sources of infection including spas, showers and fountains. It also included a fourteen day diary of places visited, routes and journeys in the fourteen days before onset, with each day divided into morning, afternoon and evening. Completed trawling questionnaires were sent electronically by secure email to Health Protection Scotland. The postcodes were added for all locations mentioned in the questionnaires and entered in to a password protected database to provide baseline data for spatial analysis. Data validation was conducted on a number of levels:  Database
The formats were set to match the nature of the data being recorded (for instance, text, number, date). Dropdown menus were used to limit input to permitted pre-defined values.  Post-capture
A compulsory data validation process was incorporated. Errors were displayed on a general validation screen and as part of the individual record maintenance facility. The list of validation checks was designed to strike a balance between identifying obvious errors (for instance date inconsistencies) and the need to record accurately what was on the questionnaire. Anonymised datasets: demographics, onset, hospitalisation dates and locations recorded in the fourteen day diaries were extracted from the database and shared with the Microbial Risk Assessment Group at the Health Protection Agency, Porton Down.
2.2.4 Temporal and Spatial Modelling Group
A modelling group was established as a sub-group of the Incident Management Team. The group was chaired by Health Protection Scotland and comprised NHS Lothian Health Protection Team, Bioterrorism and the Emerging Disease Analysis Microbial Risk Assessment Emergency Response Group, Health Protection Agency, Porton Down and the United Kingdom Meteorological Office. The group met for the first time on Thursday 7 June 2012, and met on three further occasions with the final meeting on 26 June 2012. Two data extracts from the line listing and four data extracts from the trawling questionnaire database were sent to the Microbial Risk Assessment Emergency Response Group, Porton Down. The group based in Porton Down has specialist expertise type in the statistical modelling techniques used here to help determine the likely release period and location of the source of the outbreak. The analysis included:  Statistical calculation of the release window based on the epidemic  Cluster analysis  Attack ratio analysis The Meteorological Office provided data on meteorological conditions including wind speed and direction for the affected area. Wind roses were generated using numerical weather prediction data for the coordinates of cooling tower locations in the affected area. A wind rose is the usual way of showing the wind, direction and speed, over a period of time at a specific location. Wind direction is given as the direction from which the wind is coming (hence a south-westerly wind will transport airborne substances in a north-easterly direction). These wind roses were provided for cooling tower locations by day and by week for the likely exposure period. The Meteorological Office used the Lagrangian dispersion model NAME (Numerical Atmospheric-dispersion Modelling Environment), driven by meteorology from the Meteorological Office's 1.5km resolution limited area Numerical Weather Predication model. They took the Microbial Risk Assessment Emergency Response Group's modelling work and used the Numerical Atmospheric-dispersion Modelling Environment model to investigate the geographical areas that contributed most significantly to the air that arrived at two separate areas that were identified as potential regions of infection.
2.3 Results of descriptive and analytical epidemiology and modelling

2.3.1 Case numbers
In total, 92 cases were identified in the outbreak; 56 confirmed cases and 36 probable and possible cases. Seven of the confirmed cases and two in the probable and possible category were identified outwith NHS Lothian. Table 1: Total number of confirmed, probable and possible cases,
by location
Clear and concise case definitions are essential for the categorisation of cases. However, determining the final case status can require additional microbiological typing and epidemiological information, both of which take time to obtain and analyse. Once such data becomes available, this can result in the re-classification of some individuals. These final figures differ, therefore, from some of those reported during the outbreak investigation. This reflects the additional clinical and microbiological information that made available subsequent to the earlier reports. Over 1000 symptomatic people were tested and treated in Primary Care practices in the affected area between 14 May 2012 and the end of June 2012. It is likely that some of these cases in the community had the less severe, self limiting form of legionellosis but did not go on to develop pneumonia. A post outbreak serosurveillance study has been investigating the whether this is the case.
2.3.2 Deaths
Four deaths have been reported among confirmed cases. The case fatality rate was 7.1% among confirmed cases and 4.3% amongst all cases. The fourth death has been classified as confirmed based on microbiological analysis by expert advisers to the Incident Management Team. The evidence from the specialist investigation (sequence based typing using a nested PCR) is consistent with the patient having been infected with the same strain of Legionella as the other culture confirmed cases.
2.3.3 Dates of onset
The onset dates for the confirmed cases ranged from 17 May 2012 to 23 June 2012 (Figure 1). It was difficult to get an accurate history of the onset of symptoms from the patient with the latest date of onset so this date may not be precise.
2.3.4 Age and sex of cases
Among the 56 confirmed cases 41 (73.2%) were male and 15 (26.8%) female. Their ages ranged from 32 to 85 years, mean 57.1 years, median 58.0 years. The mean age for males was 56.0 years and 60.1 years for females. This difference was not significant (p = 0.269). Probable and possible cases were aged 20 to 88 years, mean 55.2 years, median 54.5 years.
2.3.5 Underlying medical conditions
Among the confirmed cases 70% (39/56) had a serious underlying medical condition, 16% (9/56) were diabetic and 25% (14/56) had a condition or were on treatment that was likely to result in immuno-suppression. Forty-four out of the 56 (79%) confirmed cases were reported to be current smokers compared with 19% in the overall Lothian population 1 and 9% (5/56) were reported to have excess alcohol consumption (based on a clinical assessment of alcohol consumption greater than 21 units per week for males and 14 units for females). 1 Health and Lifestyle survey 2010, Community Health Partnership Figure 1: Onset date for confirmed cases of Legionnaires' disease.

Onset date for confimed cases of Legionnaires' disease
(onset dates for 55 confirmed cases, date of onset not known for one case)
Onset date
 There is no onset date for one further confirmed case (total =56) Figure 2: Age band and sex of confirmed cases of Legionnaires' disease.

Age band and sex of confirmed cases of Legionnaires' disease (n=56)
0-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 2.3.6 Temporal and Spatial modelling results
The release end date based on all cases submitted to the modelling group was estimated to be 30 May 2012 (95% confidence intervals -28 May 2012 to 2 June 2012). When the model was repeated using only confirmed cases of Legionnaires' disease the release end date was estimated to be 28 May 2012 (95% confidence intervals 25 May 2012 to 30 May 2012). The cluster analysis was conducted using onset date, hospitalisation date, including and excluding unconfirmed cases. All the results suggested a single cluster of cases. The attack ratio analysis using postcode geography is illustrated in Figure 3. The results suggest a source near or in the EH11 2 postcode sector in the Gorgie area of Edinburgh. The attack ratios appear to drop three orders of magnitude from zone A (which includes the putative source) radiating out to zone E which is further away from the putative source. The Microbial Risk Assessment Response Group noted that while such ‘radial' attack analysis had been used elsewhere to consider Legionnaires' disease outbreaks this technique has not previously been applied to postcode geography. The denominator populations for these models were taken from the National Population Database created by the Health and Safety Laboratory (NPD) estimation of residential population. This will not reflect the true daytime population of the area, but is indicative for this purpose and a reasonable estimate.
2.3.7 The United Kingdom Meteorological Office modelling data supported
the possibility that cooling towers in south west Edinburgh could be the source of Legionella in this outbreak.
2.3.8 Epidemiological evidence obtained through mapping of cases, analysis
of travel diaries and complex meteorological analysis of wind speed and direction suggests that a common outdoor airborne exposure occurred over south-west Edinburgh with an estimated release end date of 30 May 2012 (95% confidence intervals - 28 May to 2 June 2012) and is consistent with the putative source of the airborne bacteria being from cooling towers located in south west Edinburgh. Figure 3: Attack ratio analysis using postcode geography.

2.4 Follow up Analytical Epidemiological investigations
A number of further investigations are ongoing. These include a seroprevalence study and a case control study. This report contains preliminary finding from these studies. The final outcomes of these studies will inform further public health action and our continued improvement of the management of future outbreaks.
2.4.1 Prevalence
2.4.1.1Symptoms and prescribing
Non-pneumonic legionellosis is the less severe, self-limiting form of legionellosis and is often known as Pontiac fever. During the outbreak over 1000 people in south west Edinburgh sought medical attention with a range of symptoms. Where appropriate, they were prescribed the antibiotic clarithromycin by their General Practitioner. Primary care data on these cases was reviewed. Clarithromycin prescribing was used as a preliminary proxy measure to ascertain the extent of healthcare sought for symptoms of legionellosis. Primary care prescribing data was extracted from the Prescribing Information System for Scotland (PRISMS). It showed that whilst there is normally a seasonal dip in clarithromycin prescribing over the summer months, this was not the case in 2012. Figure 5 shows a peak in clarithromycin prescribing in June 2012. Other areas of Lothian did not experience such peaks (data not shown) indicating that the increase was likely to be a direct result of the Legionnaires' outbreak. Figure 5: Clarithromycin dispensing, items dispensed in south west
Edinburgh practices, calendar month, 2009
Chart x: Clarithromycin dispensing - items dispensed - South West Edinburgh LHP
Source: PRISMS

2.4.1.2Seroprevalence study
A seroprevalence study was carried out to further determine the extent of non-pneumonic legionellosis (Pontiac fever) amongst those who sought healthcare during the outbreak and the characteristics, symptom profiles and risk factors associated with this group of people. Invitations to participate in the study were sent to every individual over 18 years old, resident in the exposed area between 14 May and 6 June 2012, registered with one of seven general practices located in the centre of the exposed geographical area who had developed symptoms of non-pneumonic legionellosis and sought healthcare, for legionellosis, between 14 May and 27 June 2012. This group comprised 915 individuals. The study comprised donating a sample of blood and completing a self-administered questionnaire six to eight weeks after the outbreak was officially declared. The study population was predominantly female (58%) with a mean age of 47 years. The participation rate was 31.4% (n=282) with 65% of those who participated being female with a mean age of 52 years. Non pneumonic Legionellosis (Pontiac fever) has no single agreed clinical definition. In this investigation we used one of the stricter clinical definitions "fever and either cough, headache or muscle aches". When this clinical definition was applied to the 282 participants, 48% (n=135) fulfilled the clinical case definition. Only a small number (n=6) showed serological evidence of an immune response to Legionella. These six individuals had an antibody detected at a titre of >16 (range 32 to 128). Subsequent samples taken from these individuals either reverted to negative (three of the six) or remained positive but at a lower titre (range 16 to 32) indicating possible recent infection with the Legionella bacterium. These preliminary results suggest that only a small percentage of the cohort of patients who attended their General Practitioners with symptoms in May and June 2012 showed recent infection with the Legionella bacterium .
2.4.2 Case-control
Alongside the seroprevalence study exploring those with non-pneumonic legionellosis, a case control study is being undertaken. The aims of the case control study are to quantify the relationship between wet cooling systems (a potential source of aerosolised Legionella) and cases of Legionnaires' disease, and secondly, to identify further the characteristics and risk factors associated with Legionnaires' disease. Interviews with cases and controls were undertaken by City of Edinburgh Council and NHS Lothian Public Health staff. Analysis of results is on-going and a full report will be made available. Preliminary analysis suggests that most cases experienced confusion and altered mental state; many had limited memory of the period of illness. These symptoms seem more common than has been reported previously and this is being investigated further. If confirmed, this could help explain the discrepancy between recovery from illness as documented using physical measures and patient reports of a longer-lasting illness.  A fourfold or greater rise in specific serum antibody titre to L. pneumophila sg1 is considered to be a confirmatory diagnosis for Legionnaires' disease. A single high serological titre result is considered to indicate recent Legionella infection in the presence of compatible symptoms. 3. Medical Microbiological Investigation of clinical cases
The identification of the outbreak followed the notification to Public Health by Medical Microbiology of four inpatients, admitted over a four day period to Critical Care in NHS Lothian. All had severe community acquired pneumonia and were confirmed as positive for Legionella pneumophila Sg 1 urinary antigen. Following the identification of the outbreak over the weekend of 2 and 3 June 2012, further possible cases were identified by clinical suspicion on presentation to acute care, and through active case finding by clinicians and medical microbiologists. Advice to clinicians on medical microbiological testing was issued by Medical Microbiology and Public Health on Monday 4 June 2012 and updated by Medical Microbiology on Friday 8 June 2012. Clinicians were advised to submit urine for detection of L. pneumophila serogroup 1 urinary antigen, sputum or broncho-alveolar lavage samples for molecular testing and culture, and paired sera for specific antibody detection.
3.1 Methodology for medical laboratory processing of diagnostic
samples
Samples for microbiological testing were processed according to the
NHS Lothian Department of Laboratory Medicine standard operating
procedures. Detection of L. pneumophila Sg 1 urinary antigen was
performed using a rapid, specific immunochromatographic assay
(BinaxNOW Legionella Urinary Antigen Test: Alere)
An in-house multiplex real-time polymerase chain reaction (PCR) assay
was used at the Royal Infirmary of Edinburgh, Molecular Microbiology
Laboratory to detect Legionella pneumophila and Legionella species in
respiratory samples. Samples positive by PCR were referred to the
Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus
Reference Laboratory for enrichment culture and identification and
typing.
Legionella cultures at the local laboratory were performed on Buffered Charcoal Yeast Extract (BCYE) agar and were incubated for 7-10 days at 35-37 degrees Centigrade. Post-mortem samples were submitted by NHS Lothian Department of Forensic Pathology. A standardized proforma was used for chain of evidence specimen collection and processing. Legionella isolates cultured at the Royal Infirmary of Edinburgh Laboratory from post-mortem samples from the patients who died, were also referred to Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory. Samples from hospital inpatients and cases presenting at NHS Lothian unscheduled care departments were prioritised. There was a low positivity rate in samples from patients presenting to general practitioners. An algorithm was developed to advise General Practitioners on the management of less unwell patients who did not require submission of a sample, and was issued to Lothian Unscheduled Care Services on Friday 8 June 2012, and to General Practitioner practices on Monday 11 June 2012.
3.2 Medical Microbiology Results
Sixty four patients with pneumonia tested positive for Legionella pneumophila Sg1 by urinary antigen detection, culture, respiratory Polymerase Chain Reaction (PCR) or serology. Positive cultures were obtained from 15 of these patients and the causative organism was identified at the Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory as Legionella pneumophila Sg1, monoclonal subtype Knoxville, sequence based type ST 191 (6,10,19,28,19,4,6). 3.3 Antimicrobial treatment of probable, possible and confirmed cases
Patients with severe pneumonia were treated with intravenous levofloxacin 500 mg twice daily. Intravenous clarithromycin 500 mg twice daily was added at the discretion of the treating clinician, in view of the potential small risk of cardiac electrophysiological abnormalities with quinolone/macrolide combinations (British Thoracic Society Guidelines 2009). Information on the use of antibiotics in the treatment of Legionnaires' disease in specific patient groups was prepared by the Lothian Medicines Information Service and circulated to clinical teams. Recommended dose adjustments were made for both levofloxacin and clarithromycin when treating patients with renal impairment. No dosage adjustments were made for patients with hepatic impairment, but hepatic function was monitored closely. 4. Impact of the outbreak on services in NHS Lothian
4.1 Primary
Media coverage of the outbreak from Sunday 3 June 2012 led to increased public awareness of the outbreak across Edinburgh. Primary care practices in the affected area and Lothian Unscheduled Care Services reported marked increases in telephone and face to face consultations during the week commencing Monday 4 June 2012. This increased following the initiation of the NHS 24 Helpline on 6 June 2012 and the house to house leaflet drop which started in the middle of that week. Practices did manage to cope with the increased numbers of patients but were under severe pressure. Over 1000 patients were investigated and treated in primary care.
4.2 Acute
Care
Forty-five of the confirmed cases were admitted to acute hospitals in NHS Lothian during late May and June 2012. Twenty one of the cases were admitted to the Royal Infirmary and 24 to the Western General Hospital. Twenty-two patients required admission to Critical Care; 19 were admitted to Intensive Care and three to a High Dependency Unit. An NHS Lothian Bed Management Team met twice daily for the duration of the outbreak. This involved teleconferencing with all three acute sites in NHS Lothian with input from bed managers and senior clinicians in Acute Medicine and Critical Care. Clinical guidance and information was disseminated by this team across NHS Lothian. A situation report on hospital and Critical Care beds and up to date numbers of probable, possible and confirmed cases was produced after each meeting and disseminated to key staff. Although no elective surgery was cancelled over the first week of the outbreak, five cases booked for elective surgery at the Western General Hospital requiring Critical Care use post operatively were deferred. In addition three elective patients booked for Critical Care at the Royal Infirmary of Edinburgh were held in recovery overnight. Critical Care surge management plans had been updated following the 2009 influenza A/H1N1 pandemic and these were utilised for planning for possible further increases in cases. Neighbouring Health Board Critical Care teams were consulted and volunteered to provide further capacity if the need arose. The mean length of stay in the intensive care unit was 11.3 (±7.6) days and mean hospital length of stay for those who were admitted to intensive care unit was 23.0 (±16.9) days. For all hospitalised patients the mean length of stay was 15.7 (±14) days. 4.3 Critical
Of those patients admitted to Critical Care in Lothian, 17 (77%) required mechanical ventilation. In those patients who were ventilated, the mean duration of ventilation was 10.3(±6.0) days. Three patients (18%) required prone ventilation for severe Acute Respiratory Distress Syndrome, two (12%) required treatment with inhaled nitric oxide, one (6%) required high frequency oscillatory ventilation and one (6%) required referral for extra-corporeal membrane oxygenation (ECMO). Six patients (29%) required renal replacement therapy for acute kidney injury.
4.4 Resources
sub-group
The report of a case of anthrax in Scottish Borders highlighted the
importance of establishing a resources sub-group to manage large or
complex incidents. In this outbreak, the Director of Finance oversaw the
initial phase personally as executive on call and the Joint Management
Team of NHS Lothian agreed to ensure that the necessary resources
were made available. Two members of finance staff were delegated
responsibility for gathering, analysing and costing resource use based
on existing guidance. The Director of Finance, Director of Public Health
and Health Policy, Director of Strategic Planning, Performance and
Information and the Director of Operations for Acute Medical Specialties
met once on 3 July 2012 to confirm the principles and processes being
followed and to ensure no areas of potential concern had been
overlooked.
Estimated costs to NHS Lothian associated with this outbreak
Table 2 below sets out the estimated costs to NHS Lothian associated with this outbreak. Table 2: Estimated costs to NHS Lothian associated with the
outbreak of Legionnaires' disease June 2012.
Expenditure area
Acute hospital admissions by Legionnaires' patients Public information -leaflet delivery -NHS 24 helpline Enhanced staffing Increased prescribing costs Laboratory costs Public Health – staffing and resources* Further Public Health investigation Total estimated costs
*this does not take account of all the staff that came in early/stayed late and undertook additional tasks or provided mutual aid 5. Update on other investigations
5.1 The environmental investigations have been aimed at establishing the
potential source of the Legionella organism causing human illness. Water samples were taken from installations across south west Edinburgh which had the potential to generate plumes of aerosols. These included cooling towers, sprinkler systems and a vehicle washing bay. Maintenance data for these installations were also inspected as part of the investigation.
5.2 Meteorological data were reviewed to determine wind direction and
strength in the outbreak area around the estimated exposure period to establish the relationships between the distribution of cases and plume dispersal (also see section 2.2.4). An epidemiological model was used to confirm the relationship between postcode distribution and plume dispersal taking into account wind direction, wind speed, the height of the individual cooling towers and evaporative condensers above ground level.
5.3 Findings from the environmental investigations carried out have not yet
been conclusive in identifying the exact source of the outbreak. Viable Legionella bacteria were not isolated from the environmental water samples. Further investigations which use new techniques involving whole genome DNA sequencing are currently being undertaken to generate information that might provide information on the timing and geography of likely acquisition by individual patients. Similar sequencing may be possible on Legionella DNA isolated from environmental water samples. It is hoped that this detailed investigation will establish a relationship between the patient and environmental samples. 5.4 Health and Safety enforcing authorities are investigating
circumstances of the deaths under the direction of the Crown Office and Procurator Fiscal Service Health and Safety Division.
5.5 The Health and Safety Executive issued a safety bulletin to all users of
cooling towers and evaporative condensers on 27 July 2012 drawing their attention to the key aspects of the proper management of the risks from Legionella. It was informed by a Health and Safety Executive review of outbreaks in Britain over the past ten years that showed common failings in control, and a potential risk of further Legionella outbreaks, such as that in Edinburgh in June 2012 http://www.hse.gov.uk/safetybulletins/coolingtowers.htm. As a result of the review, Health and Safety Executive and Local Authorities are currently carrying out a programme of visits to all sites with cooling towers and evaporative condensers across Britain to ensure that duty holders are effectively controlling Legionella risks. 6. Conclusion
In conclusion, this was a large outbreak of Legionnaires' disease affecting the population of south west Edinburgh and caused considerable impact on NHS services during June 2012. Appropriate control measures were applied quickly and work is continuing to prevent any future similar outbreaks. The NHS Lothian Incident Management Team has conducted structured debriefs of the incident response. Analysis of these debriefs indicate that the locally co-ordinated Public Health, Environmental Health and clinical response (primary care, and adequate Critical Care, Lothian Unscheduled Care Service, Accident and Emergencies and Laboratory services) helped prevent ongoing exposure of the population and mitigated associated mortality and morbidity. The mutual aid and support of colleagues from across NHS Lothian and Public Health staff from other Health Boards was essential in enabling an effective response to this outbreak, another public health incident that occurred over the same period and in enabling the routine response to be maintained.
7. Recommendations
NHS Lothian and the other agencies involved in managing the response and investigations into the outbreak are now taking forward the following key actions:
7.1 Revise the Health Protection Network guidance to reflect current best
practice and organisational arrangements regarding the responsibilities
of regulators, other agencies and expert bodies to advise and/or address
issues such as sampling (techniques and reporting results) and
processes to be followed whether there is a potential for future
investigation of the attribution of corporate responsibility, including
homicide.
Lead: Health Protection Advisory Group to advise Chief Medical
Officer and Scottish Directors of Public Health Group on recommendations.
7.2 Develop a common approach for the recording of complex
microbiological and environmental information across agencies such as
the Health and Safety Executive, local authority Environmental Health
and Scientific Services and National Reference Laboratories.
Lead: Health Protection Advisory Group to advise Chief Medical
Officer
Scottish Directors of Public Health Group on recommendations.
7.3 Review resources and facilities required for emergency planning and
resilience to ensure that all agencies involved in the management of a
major outbreak can respond formally to a major outbreak in a timely
manner and maintain their response as required.
Lead: All agencies involved to review against updated Scottish
Government and United Kingdom guidance during 2013. 7.4 Rehearse the local multiagency major outbreak plan on an annual basis
and regularly review roles and agree tasks within and across agencies.
Lead: NHS Lothian and all partner agencies
7.5 Develop a suite of templates/procedures to support for rapid distribution
of information to patients, public and professionals by all appropriate
means.
Lead: NHS Lothian in line with Health Protection risk communication
and Scottish Government guidance APPENDICES
APPENDIX 1:
INCIDENT MANAGEMENT TEAM MEMBERS APPENDIX 2:
DATES OF INCIDENT MANAGEMENT TEAM AND SUB GROUP MEETINGS APPENDIX 1
INCIDENT MANAGEMENT TEAM MEMBERS
Alison McCallum
Sian Tucker
Lynn Cree
Director of Public Health and Acting Clinical Director, Lothian Environmental Health Adviser Unscheduled Care Service (LUCS) Health Protection Scotland Alison Smith-Palmer
Steve Harvey
Mary Hanson
Emergency Planning Officer Consultant Microbiologist Health Protection Scotland Andrew Campbell
Michael Gillies
Environmental Health Officer Consultant in Public Health Medicine Clinical Director of Critical Care City of Edinburgh Council Christine Evans
Alison Potts
Robbie Beattie
Consultant in Public Health Medicine Scientific and Environmental Health Protection Scotland Services Manager City of Edinburgh Council Dona Milne
Alistair McNab
Specialist in Public Health Head of Operations Lead Health Protection Nurse Health and Safety Executive Fatim Lakha
Carol Harris
Stuart Wilson
Specialist Registrar, Communications Manager Director of Communications Public Health Medicine
Giles Edwards
Colin Sibbald
Consultant Microbiologist Food Health and Safety Manager Scottish Haemophilus, Legionella, City of Edinburgh Council Meningococcus and Pneumococcus
Reference Laboratory
Janet Stevenson
Duncan McCormick
Consultant in Public Health Medicine Consultant in Public Health Medicine
Jim McMenamin
Garry Stimpson
Consultant Epidemiologist HM Principal Inspector Health Protection Scotland Health and Safety Executive
Louise Wellington
Diane Lindsay
Health Protection Nurse Principal Clinical Scientist Scottish Haemophilus, Legionella, Meningococcus and Pneumococcus Reference Laboratory Martin Donaghy
Jennifer Irvine
Medical Director PA in Public Health Health Protection Scotland
Jonathan Mills
Specialty Registrar, Medical Microbiology Team Leader, Occupational Hygiene Te Health and Safety Executive
Richard Othieno
Consultant in Public Health Medicine APPENDIX 2
INCIDENT MANAGEMENT TEAM AND SUB GROUPS MEETING DATES
Incident Management Team Dr Duncan McCormick, NHS Lothian Sunday 3 June 2012 Incident Management Team Dr Duncan McCormick, NHS Lothian Monday 4 June 2012 Incident Management Team Dr Duncan McCormick, NHS Lothian Tuesday 5 June 2012 Incident Management Team Dr Janet Stevenson, NHS Lothian Wednesday 6 June 2012 Surveillance Meeting Dr Janet Stevenson, NHS Lothian Thursday 7 June 2012 Spatial Analysis Meeting Dr Jim McMenamin, Thursday 7 June 2012 Health Protection Scotland Incident Management Team Dr Duncan McCormick, NHS Lothian Friday 8 June 2012 Clinical Guidance Meeting Dr Mary Hanson, NHS Lothian Friday 8 June 2012 Incident Management Team Dr Sue Payne, NHS Lothian Saturday 9 June 2012 Incident Management Team Dr Sue Payne, NHS Lothian Sunday 10 June 2012 Incident Management Team Dr Richard Othieno, NHS Lothian Monday 11 June 2012 Laboratories Meeting Dr Martin Donaghy Tuesday 12 June 2012 Health Protection Scotland Incident Management Team Dr Richard Othieno, NHS Lothian Wednesday 13 June 2012 Spatial Analysis Meeting Dr Jim McMenamin, HPS Thursday 14 June 2012 Incident Management Team Dr Richard Othieno, NHS Lothian Friday 15 June 2012 Surveillance Meeting Dr Janet Stevenson Monday 18 June 2012 Spatial Analysis Meeting Dr Jim McMenamin Monday 18 June 2012 Incident Management Team Dr Richard Othieno, NHS Lothian Wednesday 20 June 2012 Spatial Analysis meeting Dr Alison Smith-Palmer Tuesday 26 June 2012 Health Protection Scotland Incident Management Team Dr Janet Stevenson, NHS Lothian Tuesday 26 June 2012 Incident Management Team Dr Richard Othieno, NHS Lothian Tuesday 3 July 2012 Resources Sub-Group Dr Alison McCallum, NHS Lothian Tuesday 3 July 2012 Incident Management Team Dr Richard Othieno, NHS Lothian Tuesday 10 July 2012 Incident Management Team Dr Richard Othieno, NHS Lothian Tuesday 17 July 2012 Incident Debrief Steve Harvey, NHS Lothian Wednesday 1 August 2012 Incident Management Team Dr Janet Stevenson, NHS Lothian Wednesday 22 August 2012 Incident Management Team Duncan Friday 21 September 2012 McCormick, NHS Lothian Incident Management Team Dr Duncan McCormick, NHS Lothian Thursday 20 February 2013

Source: http://www.h2ochemicals.co.uk/files/Edinburgh%20Outbreak%20Interim%20Report%2023%20July%202013.pdf