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Outbreak Management

Outbreak Management. E.McNamara PHL,HSE,SWA. and St James’s Hosp. Outbreak definitions. Cluster - 2+ cases - related in time/place - may not be above expected Outbreak - as cluster but - exceeds expected number Epidemic - as outbreak - but implies crisis .

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Outbreak Management

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  1. Outbreak Management E.McNamara PHL,HSE,SWA. and St James’s Hosp.

  2. Outbreak definitions • Cluster - 2+ cases - related in time/place - may not be above expected • Outbreak - as cluster but - exceeds expected number • Epidemic - as outbreak - but implies crisis.

  3. 1 Preliminary assessment • Is it an outbreak? • Confirm the diagnosis • Is further investigation needed? • Epidemiological • Environmental • Microbiological • Any immediate control measures?

  4. Preliminary assessment - is it an outbreak? • Who identified problem? • How many cases or deaths? • Expected number of cases or deaths? • What tests done and any results? • Any change in clinical or lab practice? • Any obvious link between cases?

  5. Preliminary assessment- confirm the diagnosis • Review clinical case histories • Interview several cases • Discuss tests/specimens with lab • Arrange tests/get results quickly • Repeat tests or confirmatory tests? • Consult experts?

  6. Preliminary assessment - Is further investigation needed? • illness serious? • Cases still occurring? • More than 1 location involved? • Any secondary cases? • Risk of recurrence?

  7. Preliminary assessment - immediate control measures? • Prevent further cases: • Stop symptomatic food handlers working? • Close ward, Stop admissions? • Clean/disinfect premises or equipment? • Cease drinking water? • Close premises/stop production? • Review operational practices • Recall product? • Prevent person-to-person spread • Offer prophylaxis e.g. immunisation

  8. Case definition and identification Case ascertainment • Case definition • Define population at risk • Quantification of incident.

  9. Time Place Person Symptoms Lab results. Confirmed Probable Possible Master List Case definition and identification:

  10. Descriptive study: Time, place and person • Data collection standard format line listing denominator data • Data analysis epidemic curve attack rates Generate Hypothesis.

  11. Analytical studies?To Test hypothesis Cohort Study • Start with population (cohort) exposed to factor • Calculate relative risk (RR) of exposure. Case-control study • Start with cases • Identify controls • Calculate odds ratio (estimate of RR)

  12. Special studiesVerify hypothesis, Source. • Microbiological • Identify Pathogen • Typing of isolates • Food and environmental samples? • Other Specialities • Veterinary, Enviromental • Meteorological data • Tracer studies e.g. water, air • Entomological

  13. Control Measures • Remove source Isolate/treat case Destroy/treat food or other source • Protect persons at risk Hygiene/prophylaxis • Prevent recurrence Make recommendations Produce guidelines/change law Audit interventions

  14. Communication • During the investigation • Information for public and professionals • At the end of the investigation Produce written reports • For those involved, critical appraisal. • For enforcement • For wider publication

  15. Outbreak Preplanning • External; Multidisciplinary. • Internal; Robust protocols • PHL, HSE,SWA. Annual • 11 major enteric outbreaks • 58 minor incidents

  16. Role of Outbreak Control Team (OCT). • Prelim. Assessment. • Case ascertainment • Hypothesis • Descriptive studies • Analytical studies • Special studies • Control measures

  17. Emergency Plan for Outbreaks • OCT; roles, responsibilities and legislation. • Multidisciplinary • Strategy to investigate and manage, SOP. • Risk assessment, Interventions, Monitor effectiveness. • Adequate surge resources. • Communication: internal, external, media.

  18. OCT • Meetings minuted. • Multidisciplinary updates. • Continuous reassessment of public health risk. • Rationale for interventions, agreed, designated and time frame. • Conclusion, Debriefing, lessons learnt. • Recommendations to prevent recurrence. • Outbreak report.

  19. Initial OCT Meeting • Confirm: • PHL sample receipt requirements • Pathogen analysis. • Health and safety issues • PHL result communication, format, status, to whom. • Clinical advice and interpretation • Pathogen/sample storage • PHL liason person attending OCT.

  20. OCT Meetings (Lab.) • Provide update on lab.results. • Provide specialist result interpretation. • Advise on pathogen related risk assessment. • Advise on infection control. • Advise on interventions.

  21. PHL Outbreak Plan • Notification, Outbreak code. • Specimen receipt • Urgency, quantity, type. • Time and mode of delivery • Pathogen screen • Request details, O/B code, GP, contact Nos. • Documented chain of custody • Rejection criteria

  22. Health and Safety Advice • For patient sample procurement • For sample collector • Sample packaging and transport • At lab. reception • During analysis • Sample disposal

  23. Internal Laboratory Briefing • Clarify nature of outbreak. • Outbreak code • Designate Senior Technologist as Outbreak Co-ordinator. • Confirm agreed communication route with OCT. • Methodology, IQC and safety.

  24. Briefing cont. • Establish potential sample numbers • Devise outbreak staff rota and duties. • Consider deferring routine work. • Do stock audit. • Review lab. space. • Documentation; Receipt,Tech. work. • Document daily dispatch of cumulative validated results to agreed personnel.

  25. Reference Laboratory • Establish early communication. • Source of advice. • Clarify: • Typing methods • Turnaround time • Urgency • PHL contact person

  26. Outbreak conclusion • Attend debriefing. • Assess lab. response. • Review lessons learnt. • Modify lab. plan if necessary.

  27. Investigation of a Outbreak.

  28. Index Case • 19 Y/O • Admitted SHB Bloody Diarrhoea 23/6/04 • Fri. 25/6/04 PHD notified ?E.coli 0157. • What next?

  29. Day 1 • Confirm VTEC • Farm-Fork investigation, sporadic case. • Exposure Hx. • Dietary • Water • Recreational • Occupational • Initiate investigation.

  30. Day 1 cont. • P H Dept, SHB link to NEHB • EHO’s SHB, MWHB, NEHB • MWHB- Restaurant • NEHB- Sports ground • PHL,SWAHB notified of case and samples • Interventions?

  31. Interventions Day 1. • MWHB, Restaurant inspection and sampled • NEHB, Sports ground. • 2 pitches • Intercounty Summer festival tournament. • Private well • Water sampled • Drinking water ceased imediately.

  32. Outbreak Day 4 • 26/6 Sat, No. of foods and waters received PHL • 28/6 Day 4, • Isolate index case received from SHB. • Index case + Bar water confirmed as E. coli O157 VT1 + VT2 positive. PCR. • What next?

  33. Public Health Response Dynamic • Outbreak Situation Develops • OCT Co-ordinates • Public Health Laboratory Investigation • Public Health Interventions OCT: PH Doc, EHO, Med Micro PHL, NDSC

  34. Epidemiology, PHDept. Case ascertainment Epi curve Epi. Studies Case Control Cohort Interventions Environmental, EHO,s Premises inspection. Operational review. Sampling Interventions Closure? Outbreak Strands

  35. Premises • Sports grounds • Recent Tournaments • Playing/training pitches • Club house • Investigations?

  36. All cases exposed at sports grounds

  37. Linked Cases • Public Health • Sports festival 100+ kids 21/6-26/6 • Case assertainment • Symptomatic  Tested • Asyptomatic  not tested, advice given to them and GPs

  38. Interpret. ation?

  39. ANNUAL RAINFALL ??? QUARRY ??? BAR (drinking water) untreated ??? PRIVATE WELL SEPTIC TANK ??? ??? SURFACE WATER

  40. Water Interventions • Drinking alternative • Treatment of private well: pre + post test samples • Geographical Survey: dyeNo blackflow from septic tank • Secure Private well. • Other interventions?

  41. Other Interventions. • Playing pitch fenced • Training pitch not fenced • Animals on training pitch • No. of animal droppings sampled • Clean grounds • Washing hand notices • Fence training pitch

  42. Other samples • Sheep droppings • Received 14/7 • Non-O157, • VT1 positive • Interpret?

  43. Other samples • 14/7 clinical Sample • Contact of positive case • Non-O157 • VT1 positive • Interpret?

  44. PFGE Lane 1: DNA ladder Lane 2: Index case. Lane 3: Case 3. Lane 4: Case 2. Lane 5: case 4. Lane 6:Bar Water Lane 7: Septic tank Lane 8: Surface Water. Lane 9: DNA ladder Lane 10: Sheep droppings. Lane 11: Sheep droppings. Lane 12: Sheep droppings. Lane 13: clinical non-O157 Lane 14: DNA ladder 1 2 3 4 5 6 7 8 9 10 11 12 13 14

  45. Post intervention • Continue to screen water post treatment. • Post treatment samples tested-Negative • Enviromental water sampling?

  46. Summary • Water • Indicator Micro. = Neg. VTEC POS • Private Well vulnerability • Environment- contamination of surface water • Animal – recreational source • Importance of Non-0157 diagnosis

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