legionnaire’s disease outbreak (point source): stoke on trent, 2012 dr nic coetzee (west midlands...
TRANSCRIPT
Legionnaire’s Disease Outbreak (point source):
Stoke on Trent, 2012
Dr Nic Coetzee (West Midlands North HPU)
-- on behalf of the Outbreak Control Team
December 2012
Stoke-on-Trent
Phil Taylor
The start...
Friday 20th July 2012
• 2 cases notified – lab UHNS: interviews
• 6-10 cases/ year average - Staffordshire
• Internal incident meeting
No specific risk factors Enhanced case finding Cooling towers (LA, HSE)
Response – 29 busy days
1st weekend
Fri 20 Jul pm: 2 cases reported to HPU. Stoke residents 2
Sat & Sun 7 cooling towers assessed. Shock treatment.
Cum. cases
Week 1...
Fri 20 Jul 4pm: 2 cases reported to HPU. Stoke residents 2
Sat & Sun 7 cooling towers assessed. Shock treatment.
Mon 23 1st OCT. EOC. Inform GPs, hospitals, labs, NHS direct. Interview 5
Cum. cases
...Week 1...
Fri 20 Jul 4pm: 2 cases reported to HPU. Stoke residents 2
Sat & Sun 7 cooling towers assessed. Shock treatment.
Mon 23 1st OCT. EOC. Inform GPs, hospitals, labs, NHS direct. Interview 5
Tue 24 More cooling towers (neighbouring areas). Env sampling – epi directed: cooling towers, hot tub (JTF), water features, etc.
8
Cum. cases
...Week 1...
Fri 20 Jul 4pm: 2 cases reported to HPU. Stoke residents 2
Sat & Sun 7 cooling towers assessed. Shock treatment.
Mon 23 1st OCT. EOC. Inform GPs, hospitals, labs, NHS direct. Interview 5
Tue 24 More cooling towers (neighbouring areas). Env sampling – epi directed. Cooling towers, hot tub, water features, etc.
8
Wed 25 2nd OCT. 5 respiratory samples identical subtype. ? Point source 9
Cum. cases
...Week 1...
Fri 20 Jul 4pm: 2 cases reported to HPU. Stoke residents 2
Sat & Sun 7 cooling towers assessed. Shock treatment.
Mon 23 1st OCT. EOC. Inform GPs, hospitals, labs, NHS direct. Interview 5
Tue 24 More cooling towers (neighbouring areas). Env sampling – epi directed. Cooling towers, hot tub, water features, etc.
8
Wed 25 2nd OCT. 5 respiratory samples identical subtype. ? Point source 9
Thu 26 1st Health Advice Cell meeting 11
Fri 27 3rd OCT. Review all potential sources (registered/ unregistered) 15
Cum. cases
...Week 1
Fri 20 Jul 4pm: 2 cases reported to HPU. Stoke residents 2
Sat & Sun 7 cooling towers assessed. Shock treatment.
Mon 23 1st OCT. EOC. Inform GPs, hospitals, labs, NHS direct. Interview 5
Tue 24 More cooling towers (neighbouring areas). Env sampling – epi directed. Cooling towers, hot tub, water features, etc.
8
Wed 25 2nd OCT. 5 respiratory samples identical subtype. ? Point source 9
Thu 26 1st Health Advice Cell meeting 11
Fri 27 3rd OCT. Review all potential sources (registered/ unregistered) 15
Sat & Sun ? Hot tub – same SBT as respiratory samples ! Re-check
Cum. cases
Spa pool/hot tub -JTF - retail ‘Mega’ discount store
Week 2
Mon 30 Probable source (JTF store). Media briefing. 1st death. 18
Tue 31 Worried well – GP queries. GP letters, NHS direct. 19
Wed 1 Aug 4th OCT. All env samples negative – apart from hot tub & 1 cooling tower (different SBTs). 2nd Health Advice Cell meeting.
Thu 2 15 discharges from hospital.
Fri 3 5th OCT. No further positive env samples. LA legal proceedings. FOI requests start.
20
Sat & Sun
Week 3 and 4
Mon 6 Two remaining cases in hospital. 2nd death in hospital.
Tue 7 Last confirmed case detected 21
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Tue 14 Last OCT
Fri 17 Aug Day 29. Close outbreak
Microbiological Investigation
• Testing - all patients with ? pneumonia at UHNS• Neg & pos samples == Colindale• All 21 patients confirmed Legionella antigen sg 1 positive
by reference laboratory Colindale 2 were negative at local laboratory
• 11 sputum samples - 9 DNA sequence based typing confirmed Legionella pneumophila sg1 ST1268
• Unique strain, never seen before
Case Definitions
Confirmed:
Clinical/radiological pneumonia
Lab conf acute Legionella (Antigen/Culture/PCR/Serology)
Onset from 30 June 2012
Lived or visited Stoke area in 14 days before onset.
Probable:
As above + onset date from 2 May 2012.
Epidemiological Investigation
2 HPU Nurses interviewing + re-interviewing all cases;
REU staff onsite - HPU EOC:
analyse data, direct investigation;
Remote analyses - Porton mapping/modelling team;
Health Advice Group:
Descriptive Epi
21 confirmed cases + 2 earlier possible cases re-investigated.
All cases live in or around Stoke.
SEX Age Total
M F Mean Median
Confirmed 14 7 65.0 64 21
Possible 2 0 66.5 66.5 2
Total 16 7 23
Epidemic curve
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Num
ber
Date of onset of cases of Legionnaires' disease reported, by case status, Stoke-on-Trent, May-Aug 2012
Confirmed Possible
Onset to presentation: 3 – 7 days
Source drained Source confirmed
Exposure
Is source a registered cooling tower?
7 cooling towers – Stoke; 5 in neighbouring areas; total 8 sampled
Stoke cooling towers inspected - HSE/LA when 2 cases reported on weekend of 21-22/7;
Inspected & sampled 23-24/7: most already treated;
Case histories - “epi fit” - analysed
nearest postcode from home, work or place visited
Only one tower positive for Legionella:
different strain to cases and poor fit epidemiologically.
An unregistered exterior source - where?
south Stoke - highest risk for external source from home + work postcodes + prevailing winds.
>30 sites identified and risk assessed by LA/HSE.
5 sites inspected + sampled (4 negative).
Interviews, re-interviews:sites visited by confirmed cases
All 21 visited JTF Mega discount warehouse;
14 visited The Range retail outlet;
10 visited Tesco Longton;
3 visited Morrisons Festival park;
No other site visited more than twice;
3 car washes + 3 hospitals visited by 1 case each.
Sites for further investigation
JTF, The Range, Aggregate industry, Powder coating , Tesco Longton all identified - visited.
•JTF - spa bath on open display
•The Range - indoor fountains: made safe and sampled.
Legionella pneumophila sg1 ST1268 found by PCR in 9 cases & sample - spa bath at JTF.
Dates of visit obtained for 20 cases:
incubation period range 3-14 days, median of 5 days.
Environmental Investigation - summary
• >30 potential sites plus 12 registered cooling towers• 15 sites higher risk, investigated and sampled
Rob Johnston (F,W,E lab) with LA or HSE colleague Labour intensive
• JTF swab sample positive for Legionella pneumophila sg1 ST1268 strain
• Second site (cooling tower) positive culture Legionella pneumophila SG1 but ST62 strain
• All other sites negative
JTF hot tub - most probable source
JTF retail ‘Mega’ discount store
Identical unique strain – cases & hot tub, - only env source
All confirmed cases visited JTF - only
Incubation periods - consistent
Spa baths - indoor display - known source
Spa bath close to the tills/exit, - all visitors passed nearby
Lessons Learnt ...• Descriptive epi
– interviews, re-interviews....• Case finding – clinical microbiologist, GP• Respiratory samples • Water samples – rapid, expert, independent• Real-time dedicated epi support – line list and
mapping• Health advice group • Genotyping : DNA sequence based typing
... Lessons learnt
• Command & control:
Incident director
Clinical, environ investigation & OCT chair
Media and sitrep – talking head
GP liaison and acute desk support
Epi team on-site EOC
• EOC, IT • Resilience, operational demand• Media pressure, MPs ....• Safety – indoor spa pools –
public spaces
• Not swimming – sitting / lying
• Self-contained body of water - filtered & chemically disinfected.
• Not drained, cleaned, or refilled after each user
• Water heated to 30 – 40 deg C
• Hydrotherapy jet circulation +/- air induction bubbles.
Spa pools (hot spa/ hot tub/ whirlpool spa, “Jacuzzi”)
