10. Judged to be an outbreak A cluster of cases which can be linked to the same exposure. The number of meningococcal cases associated with pilgrims who have traveled for the Haj has increased, and the total number of cases to date is 14 including 4 death Judged to be an outbreak A single case of disease that has never been occurred . A 3 year old boy, case of Avian flu (HSN1), alerted the public health people around the world to start a full scale investigation
37. Epidemic Curve Propagated source epidemics Sick date Number of patients
38.
39.
40. Compare Common Source Propagated source 1.Curve Bell curve Scatter bell 2.First and last pt. < 1 IP > 1 IP 3.Transmission One source From person to person 4.Duration Short Long 5. control Eradicate source Health education
50. Test result d c Negative b a Positive No Yes Disease
51.
52. Test result d c Negative b a Positive No Yes Disease Sensitivity = P(T+|D+) = a /(a+c)
53. Test result d c Negative b a Positive No Yes Disease False-negative rate = P(T-|D+) = c/(a+c) TPF + FNF = 1
54.
55. Test result d c Negative b a Positive No Yes Disease Specificity = P(T-|D-) = d /(b+d)
56. Test result d c Negative b a Positive No Yes Disease False-positive rate = P(T+|D-) = b/(b+d) TNF + FPF = 1
57. Test result 900 200 Negative 100 800 Positive No Yes Disease Specificity = 800/1000 = 0.8 Specificity = 900/1000 = 0.9 Accuracy = (800+900)/2000 = 0.85 1000 1000
58.
59.
60.
61. Confirm outbreak and diagnosis Is this an outbreak? What is the diagnosis? Link between cases? Higher than expected? Clinical manifestation Laboratory result
62.
63. Outbreak confirmed, further investigation warranted Form outbreak Investigation & control team Epidemiologist Microbiologist Clinician Environmentalist Government Media etc. Team coordinates Field investigation
64. 2. Define case and start case-finding 3. Descriptive data collection and analysis Descriptive epidemiology Person Place Time
65. Identify & count cases Obtain Information Identifying information Demographic data Clinical details Risk factors
66.
67.
68. Identify & count cases Obtain Information Orient cases in -Time -Place -Person Analysis of Descriptive data
69.
70. Dz and rate of measles Age group ( year ) Number of pt. Medical personnel Attack rate (%) male female male female male female 20 - 24 0 1 0 6 0 16.67 25 - 29 0 3 8 29 0 10.34 30 - 34 2 2 8 22 25 9.09 35 - 39 0 1 1 11 0 9.09 40 – 44 0 1 4 4 0 25.00 45 – 49 0 0 3 0 0 0 50 + 0 0 3 2 0 0 Total 2 8 27 74 7.4 10.81
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72.
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74.
75.
76.
77. Cases Evaluate information Pathogen? Source? Transmission? Person Place Time Hypothesis setup : from all the data
