Surveillance & Outbreak Investigation.pptx

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1. Epidemiologic Surveillance Dambi Dollo University

2. Definition of Surveillance 6/14/2024 2 Surveillance is derived from the French ‘ Sur ’ (over) and ‘ veiller ’ (to watch) - hence ‘ to watch over ’. Public Health Surveillance is an on-going systematic collection, analysis, interpretation and Dissemination of health-related data essential to the planning, implementation, and evaluation of public health practice.

3. Cont… 6/14/2024 3 Surveillance can be conducted globally, regionally (like East Africa), nationally, or institutionally (single health facility-focused). It is a mechanism that public health agencies use to monitor the health of the community. It is for evidence-based setting priorities, planning programs, and taking action to promote and protect the public’s health.

4. Basic Principle 6/14/2024 4 Public health surveillance’s main function is to serve as an “ early warning system ” – providing timely information needed for action (rapid reporting, confirmation, decision making and response)

5. Surveillance System’s Good Attributes 6/14/2024 5 Simple Flexible Acceptable Sensitive; able to detect the problem Good predictive value positive; good yield Representative Timely Cost effective

6. Uses of Public Health Surveillance 6/14/2024 6 To estimate magnitude of the problem Early recognition of epidemics - detect sudden changes in disease occurrence. To identify changes in agents, host factors and health practices To follow secular (long-term) trends Projections of future trends To evaluate public health programs To generate hypotheses and stimulate research

7. Surveillance is Information for Action Surveillance Collection Analysis Interpretation Dissemination Public Health Action Assess PH status Detect outbreaks/epidemics Monitor trends in endemic diseases Define PH priorities Guide research Monitor and evaluate programs/interventions Predict outbreaks/epidemics Estimate future disease impact 6/14/2024 7

8. Sources of Surveillance Data 6/14/2024 8 Census data Mortality reports (along with birth and death certificates) Morbidity reports Hospital data Absenteeism records (school, workplace) Epidemic reports Laboratory reports and records Drug utilization records Adverse drug reaction reports Special surveys (research data, serologic surveys) Police records (injury, alcohol-related) Information on animal reservoirs and vectors Environmental data (water, food testing) Special surveillance data (injury, occupational H.)

9. Selection Criteria for Disease Surveillance 6/14/2024 9 Magnitude of the disease Feasibility of control measures Need for monitoring and evaluating the performance of a control program Resource availability

10. Types of Surveillance There are 3 main types of surveillance: 1. Passive Surveillance : A surveillance where reports are awaited and no attempts are made to seek reports actively from the participants in the system. 2. Active Surveillance : A surveillance where public health officers seek reports from participants in the surveillance system on a regular basis, rather than waiting for the reports. 10 6/14/2024

11. Types (Cont…) 6/14/2024 11 3. Sentinel Surveillance : uses a pre-arranged sample of reporting sources to report all cases of one or more conditions. Usually the sample sources are selected to be those most likely to see cases. Sentinel surveillance provides a practical alternative to population-based surveillance.

12. Main Purposes of Sentinel Surveillance 6/14/2024 12 To detect changes To direct and focus control efforts To develop intervention strategies To promote further investigations Provide the basis for evaluating preventive strategies and activities

13. Types (Cont…) 6/14/2024 13 Modified forms of surveillance include: 1. Intensified Surveillance : The upgrading from a passive to an active surveillance system for a specified reason and for a limited period (could be because of an outbreak). 2. Enhanced Surveillance : The collection of additional data about cases reported under routine surveillance

14. Critical Information in Surveillance 6/14/2024 14 Generally, a surveillance system should determine the Who, What, When, Where, and How questions. The critical information should include: Person: Age, sex Time: onset of disease, reporting period Place: Woreda, region Risk factors Number of cases (magnitude) Treatment outcome: deaths, recovery (seriousness) Mode of treatment: inpatient/outpatient

15. Case Definition 6/14/2024 15 Case definition includes: Criteria: Signs and symptoms with or without a laboratory test Restriction by time, place and person can be done depending on the nature of the disease There are 3 classification of case definitions: confirmed, probable, and possible cases.

16. Case Definition (Cont…) 6/14/2024 16 Classification of case definitions: Confirmed : a case definition by appropriate laboratory test. Probable : a case with typical clinical features of the disease without laboratory confirmation Possible/Suspect : a case with few of the typical clinical features. Use case definition consistently!!

17. Case Definition: Example 6/14/2024 17 Confirmed Malaria Case Probable Malaria Case Possible / Suspected Malaria Confirmed by laboratory test. Presence of fever, chills, headache, arthralgia , back pain…etc of sudden onset, but without laboratory confirmation. Presence of fever and headache of sudden onset without laboratory confirmation.

18. Major Advantages of Case Definition 6/14/2024 18 Facilitates early detection and prompt management of cases. Useful in areas where there is no laboratory. Facilitates observation of trends. Facilitates comparison more accurately from area to area.

19. Surveillance System With Laboratory Tests 6/14/2024 19 Clear procedures need to be designed and established for effective surveillance system that address: Specimen and Data collection Transfer of Specimen and data Feedback

20. Quality of Public Health Surveillance System 6/14/2024 20 The major indicators of quality public health surveillance system include: Acceptability Representativeness Reporting completeness Reporting timeliness Sensitivity of surveillance Specificity of surveillance

21. I. Acceptability 6/14/2024 21 Willingness of persons conducting surveillance and those providing data to generate accurate, consistent and timely data.

22. II. Representativeness 6/14/2024 22 The degree to which inference can be drawn from the information gathered by the surveillance system to the target population.

23. III. Reporting Completeness 6/14/2024 23 Proportion of all expected reports in a reporting system that were actually received.

24. IV. Reporting Timeliness 6/14/2024 24 Proportion of all expected reports in a reporting system received by a given date (due date).

25. V. Sensitivity of Surveillance 6/14/2024 25 The ability of a surveillance or reporting system to detect true health events: total number of health events detected by the system total number of true health events (as determined by an independent and more) complete means of ascertainment

26. VI. Specificity of Surveillance 6/14/2024 26 A measure of how infrequently a system detects false positive health events :  

27. Analysis of Surveillance Data 6/14/2024 27 Descriptive analysis: distribution by time, place and person Frequency of events Calculate rates- need proper denominator Observe trends: comparison current data with expected value, identify differences, and assess the relevance of the difference Draw graphs to show long term (secular) trends

28. Analysis Cont… 6/14/2024 28

29. Dissemination of Surveillance Data 6/14/2024 29 Disseminate surveillance data to all stakeholders Those who provide the reports (health providers) The community – affected/potentially affected Decision makers Disseminate report locally, nationally or globally; as deemed necessary Disseminate report timely and regularly Disseminate through appropriate media: newsletter or bulletin (paper or electronic)

30. 6/14/2024 30 . Federal MOH Central Referral Hospitals Regional Health Bureau Regional hospitals Regional laboratories Zonal Health Department District Hospital PHC facilities Woreda Health Office District hospital PHC facilities The community WHO Data Collection, Analysis, Action and Reporting Supervision and feedback .

31. Reporting and Feedback Levels (Local to International) 6/14/2024 31 Surveillance systems are networks of people and activities that maintain the process and may function at a range of levels, from local to international .

32. Evaluating and Improving Surveillance Systems 6/14/2024 32 Should be evaluated periodically to forward recommendations for improvement: To identify elements of surveillance that should be enhanced to improve its attributes, To assesses how surveillance findings affect control efforts, and To improve the quality of data and interpretations provided by surveillance.

33. Common Limitations of Surveillance Systems 6/14/2024 33 Under reporting Lack of representativeness of reported cases Lack of timeliness Inconsistency of case-definitions Lack and shortage of qualified staff Lack of motivation

34. Surveillance Vs survey 6/14/2024 34 Surveillance Relatively cheap - can often use existing systems and health personnel Allows monitoring of trends of disease over time Ongoing collection produces enough cases for the study But… Quality control may be the major problem May not provide representative data Survey More in-depth data could be collected More accurate assessment of true prevalence Can identify those which do not warrant medical care But… Costly Represents only a single point in time- does not show changes over time Recall bias can be introduced (retrospective data)

35. 6/14/2024 35 Public Health Surveillance in Ethiopia

36. Background of Disease Surveillance in Ethiopia 6/14/2024 36 Before 1998 → Multiple D/s Surveillances From 1998 – 2009 → Integrated Disease Surveillance and Response (IDSR) Starting from early 2009 → Public Health Emergency Management (PHEM)

37. Public Health Emergency Management (PHEM) 6/14/2024 37 PHEM is the process of anticipating, preventing, preparing for, detecting, responding to, controlling and recovering from consequences of public health threats so that health and economic impacts are minimized .

38. IDSR and PHEM 6/14/2024 38 IDSR and PHEM employ simplified tools for data collection and analysis & common channels for reporting and feedback. IDSR & PHEM strengthened the capacity to detect and respond to communicable disease threats and emergencies. The integration helped to maximize effective utilization of scarce resources.

39. List of Priority Diseases for Surveillance in Ethiopia 6/14/2024 39 Nationally, 23 disease were monitored until early 2009. From early 2009, twenty (20 but currently 22 ) diseases and conditions are identified as priority diseases on surveillance which are immediately and weekly reportable. Other diseases are included in HMIS

40. Immediately Reportable Diseases 6/14/2024 40 Acute Flaccid Paralysis (AFP) /Polio Anthrax Avian Human Influenza (H 1 N 1 ) Cholera Dracunculiasis / Guinea worm Measles NNT (Neonatal Tetanus) Pandemic Influenza A Rabies Smallpox SARS ( Severe Acute Respiratory Syndrome ) VHF ( Viral Hemorrhagic Fever) Yellow fever

41. Weekly Reportable Diseases 6/14/2024 41 Immediately Reportable Diseases Plus Dysentery Malaria Meningococcal Meningitis Relapsing fever Malnutrition Typhoid fever Typhus + all IRD

42. Exercise/Assignment 6/14/2024 42 According to current PHEM concerns, determine whether IRD or WRD ???????? MDSR AEFI MERS (Middle East Respiratory GBS (Gullian Bare Syndrome) and Microcephally of ZickaVirus What about these?????????????????? Flooding, Earth quake, Volcanic Eruption, landslide

43. Outbreak Investigation & Control Dambi Dollo University

44. Learning objectives 6/14/2024 44 After the end of this session, students will be able to: State different level of disease occurrences List the rationale to investigate outbreak occurrence Discuss steps in the investigation of an outbreak occurrence Describe types of outbreak occurrence Discuss the outbreak controlling strategies

45. Epidemiology in Action 6/14/2024 45 Outbreak Investigations Public Health Surveillance Community Screening Programs

46. Levels of Disease Occurrence 6/14/2024 46 Diseases occur in a community at different levels at a particular time in time: Expected Level (Predictable) and Excess of expected Expected level of occurrence of disease Endemic: the usual presence of disease from low to moderate level ==  Malaria is endemic in the lowland areas of Ethiopia. Hypo/Meso/Hyper-endemic: a persistently lower or moderate or high level of disease. Sporadic: Normally does not occur, but occasional cases occur at irregular intervals

47. Excess of what is expected 6/14/2024 47 Epidemic: The occurrence of health related condition/disease in excess of the usual frequency Outbreak: Epidemics of shorter duration covering a more limited area. Pandemic: An epidemic involving several countries or continents affecting a large number of people. example : HIV/AIDS,Covid-19 are pandemic.

48. Levels of Disease Occurrence 6/14/2024 48 . (Endemic Vs Epidemic) Epidemic Endemic Time Number of Cases of a Disease Hyperendemic

49. Levels of Disease 6/14/2024 49 . Increasing amount of disease Pandemic Epidemic Endemic Sporadic

50. What does outbreak investigation & control? 6/14/2024 50 It is the process of identifying: The cause of the epidemic The source of the epidemic The mode of transmission and Taking preventive and control measures

51. Source of an outbreak information 6/14/2024 51 Routine surveillance Health professionals Affected community members

52. What are the objectives for outbreak investigation? 6/14/2024 52 To initiate control & prevention measures The most important public health reasons for investigating an outbreak are to help guide disease prevention and control strategies. These disease control efforts depend on several factors, Including knowledge of the agent, The natural course of the outbreak, The usual transmission mechanism of the disease, and Available control measures

53. 2) Research and training opportunity 6/14/2024 53 Each outbreak should be viewed as an experiment waiting to be analyzed It presents a unique opportunity to study the natural history of the disease It could be a good opportunity to gain additional knowledge on The impact of prevention and control measures The usefulness of new epidemiology and laboratory techniques

54. 3) Public, political and legal obligations 6/14/2024 54 Politicians and leaders are usually concerned with control of the epidemic Politicians and leaders may sometimes override scientific concerns The public are more concerned in cluster of disease and potentials of getting medication It is right of the community to get treatment/service and it is government and our duty to protect the community

55. 4) Program considerations 6/14/2024 55 Occurrence of an outbreak notifies the presence of a program weakness This could help program directors to change or strengthen the program’s effort in the future to prevent potential episodes of outbreak occurrence

56. Steps of outbreak investigation and control 6/14/2024 56 Prepare to field work Establish the existence of outbreak Verifying the diagnosis Case definition and case finding Perform descriptive epidemiology Formulate hypotheses Testing hypotheses Refine hypothesis and additional studies Implementing prevention and control activities Communicate findings In practice, however, several steps may be done at the same time, or The circumstances of the outbreak may dictate that a different order be followed

57. Step 1: Prepare for field work 6/14/2024 57 Before leaving for the field, an investigator must be well prepared to under take the investigation: Investigation ( Knowledge in epidemiology and the disease of concern is important) Administrative (Logistics, administrative procedures, travel arrangements) Consultation (Health workers should know their role, and should participate in the planning phase)

58. Step 2: Establish the existence of outbreak 6/14/2024 58 An outbreak is the occurrence of more cases of disease than expected level The investigator has to compare previous case load with the current to assure the existence of the outbreak But be careful, excess cases may not always indicate an outbreak occurrence rather it may be because : Change in population size Change in case definition Change in reporting procedure

59. Step 3: Verifying the diagnosis 6/14/2024 59 The initial report may be spurious and arise from misinterpretation of the clinical features Review clinical and laboratory findings to establish diagnosis Goals in verifying the diagnosis includes: To ensure that the problem has been properly diagnosed To rule out laboratory error as a basis for the increase in diagnosed cases To ensure the diagnosed disease is possibly epidemic

60. Step 4: Case definition and case finding 6/14/2024 60 Prepare “case definition” before starting identification of cases It’s aim is to count all cases of the illness It is clinical criteria restricted by time, place and person Use sensitive or "loose case definition” early in the investigation and use "tight or strict case definition” for testing hypothesis =  We can find additional cases in - health facilities - home visit in epidemic area( kebele or gote level ) = Information required include personal Identifier (name, tell, address), demographic (age, sex, occupation), exposure history , clinical information (date of onset, outcome, sign and symptom), who report ? Information = we will do line listing by taking the above information

61. 6/14/2024 61

62. Classification of Case Definition 6/14/2024 62 Possible: cases with subjective signs and symptoms consistent with the case definition. Probable: cases with objective signs and symptoms consistent with the case definition. Definite: laboratory confirmed case

63. Step 5: Performing Descriptive Epidemiology 6/14/2024 63 Once data is collected, it should be analyzed by time, place and person The tools to be used when characterizing the epidemic are epidemic curve, spot map and attack rate The characterization often provides clues about etiology, source and modes of transmission that can be turned into testable epidemiologic hypothesis

64. 1. Analysis of epidemic by time 6/14/2024 64 We use epidemic curve to analyze by time taking - The X- axis; indicating time of onset -The y-axis; indicating the number of cases appearing Epidemic curve can tell as - nature of epidemic - hint to etiologies – etiologic agent - hint about source of exposure There are three principal types of epidemic Common source – based on source of exposure Propagative - touches mode of transmission Mixed epidemic – share characteristics of both type

65. 1. Common source epidemic 6/14/2024 65 It occurs as a result of the exposure of a group of population to a common source ( etiological agent ) It can result from a single source/ exposure of the population to the agent E.g: contaminated water supply, or food in a certain restaurant Three types Point common source Continuous common source Intermittent common source

66. A) Point common source epidemic 6/14/2024 66 Single/ones/limited time exposure to the source All exposed hosts will develop disease within one incubation period The epidemic usually decline after a few generations, either because the number of susceptible hosts fall below some critical level , or because intervention measures become effective A rapid rise and gradual fall of an epidemic curve suggests a point source epidemic

67. Typical Point source epidemics 6/14/2024 67 Minimum incubation period Peak of Outbreak  A single sharp peak of sudden onset

68. B) Continuous common source epidemic 6/14/2024 68 If exposure to a common source continues over time for days, weeks The epidemic curve has a plateau ( multimodal epi curve )/ long peak Range of exposures and range of incubation periods is different

69. C) Intermittent common source epidemic 6/14/2024 69 Results in an irregular pattern of the epidemic curve that reflects the intermittent nature of the exposure E.g. waterborne outbreak Often the graph is atypical Several sharp peaks

70. 2. Propagative /progressive epidemic 6/14/2024 70 It occurs as a result of transmission of an infectious agent from one person to another directly or indirectly There is a successive generations of cases The epidemic curve in a progressive epidemic is usually presence of successive several peaks , a prolonged duration , and usually a sharp fall Can show geographic spread of the case Example ; Malaria outbreak and different vector born disease

71. Typical Propagated Epidemic Curve 6/14/2024 71 No sharp peak

72. 3. Mixed Epidemic 6/14/2024 72 It shows the features of both types of epidemics It begins with a common source of infectious agent with subsequent propagated spread because of person – to- person transmission of the etiologic agent E.g. Majority of food borne outbreaks

73. 6/14/2024 73

74. 2. Analysis of epidemic by place 6/14/2024 74 A spot map is a simple and useful technique for illustrating where cases live, work or may have been exposed Area map if large area is affected It is important to indicate source of outbreak

75. 3. Analysis of epidemic by person 6/14/2024 75 Characterizing an outbreak occurrence by person is how we determine what populations are at risk for the disease Host characteristics : age, race, sex, or medical status and exposures-occupation, leisure activities, use of medications, tobacco and drug use etc… These influence susceptibility to disease and opportunities for exposure to risk factors We use attack rates to identify high risk groups

76. Step 6: Formulating hypothesis 6/14/2024 76 Depending on the outbreak, the hypothesis may address The exposures that caused the disease The mode of transmission Using : Subject-matter knowledge Descriptive epidemiology Talking with patients Talking with local officials The hypotheses should be testable

77. Step 7: Testing the hypothesis 6/14/2024 77 Here doing analytic studies may be useful. Association between the postulated exposure factor and the disease is tested using analytic design 1. Case control 2. Retrospective Cohort Appropriate measure of association should be made for case control, odds ratio for cohort design, relative risk Significance of statistics should be done, (Chi-square is the appropriate test, and P-value is estimated at 5 %.)

78. Step 8: Refining hypotheses and additional studies 6/14/2024 78 Search for additional cases: Locate unrecognised or unreported cases Environmental studies are equally important in some settings

79. Step 9: Implementing control and prevention 6/14/2024 79 In outbreak investigation, the primary goal is to control and prevent the outbreak. Implementing control measure should be done as soon as possible It should go in parallel to investigating the outbreak Source/ Mode of Transmission Causative Agent

80. Control measures (do early) 6/14/2024 80 Measures Directed Against the Reservoir : Reduce contact rate Reduce infectious sources- destruction of infected animal /isolation Reduce infectiousness- early treatment 2. Measures that interrupt the transmission of organisms Purification of water Pasteurization of milk Inspection procedures designed to ensure safe food supply. Improve housing conditions 3. Measures that reduce host susceptibility and Increase herd immunity - Immunization - Chemoprophylaxis - Use of antibiotics for known contacts of cases

81. Step 10: Communicating findings of investigation 6/14/2024 81 The final responsibility of the investigative team is to prepare a written report to document the investigations, findings and the recommendations The written report should follow the scientific reporting format which includes: Introduction Methods Results Discussion Conclusion, and Recommendations

82. Summary of the investigation and control of an epidemic considering procedure 6/14/2024 82 .

83. Post-Epidemic Surveillance 6/14/2024 83 The efficacy of control measures should be assessed day by day during the outbreak, a final assessment being made after it has ended this will provide a logical basis for post-epidemic surveillance, and preventive measures aimed at avoiding similar outbreaks in the future develop long term early warning system monitor environmental risk factors

84. The end 6/14/2024 84 Any questions or comments??