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Legionnaire’s Disease Outbreak (point source): Stoke on Trent, 2012

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 20 th July 2012 2 cases notified – lab UHNS: interviews

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Legionnaire’s Disease Outbreak (point source): Stoke on Trent, 2012

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  1. 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

  2. Stoke-on-Trent

  3. Phil Taylor

  4. 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)

  5. Response – 29 busy days1st weekend Cum. cases

  6. Week 1... Cum. cases

  7. ...Week 1... Cum. cases

  8. ...Week 1... Cum. cases

  9. ...Week 1... Cum. cases

  10. ...Week 1 Cum. cases

  11. Spa pool/hot tub -JTF - retail ‘Mega’ discount store

  12. Week 2

  13. Week 3 and 4

  14. 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

  15. 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.

  16. 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:

  17. Descriptive Epi • 21 confirmed cases + 2 earlier possible cases re-investigated. • All cases live in or around Stoke.

  18. Epidemic curve

  19. Source drained Source confirmed Exposure Onset to presentation: 3 – 7 days

  20. 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.

  21. 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).

  22. 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.

  23. 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.

  24. 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 SG1but ST62 strain • All other sites negative

  25. JTF hot tub - most probable source • 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 JTF retail ‘Mega’ discount store

  26. 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

  27. ... 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

  28. Spa pools (hot spa/ hot tub/ whirlpool spa, “Jacuzzi”) • 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.

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