Seminar

1. Investigation of an
Epidemic /Outbreak
Dr. Amandeep Kaur
Junior Resident

2. Contents
• Introduction
 Definitions
 Endemic vs epidemic and Outbreak vs epidemic
 Sources of information to detect outbreaks
 Early warning signals for an outbreak
• Why should we investigate outbreaks?
• Steps for investigation
• Constraints of field outbreak investigation
• Preparedness for Prevention and Control for Future Outbreaks

3. Endemic versus Epidemic
Endemic
• Constant presence of a disease or infectious agent at a usual level, without
importation from outside, within a given area or population
Epidemic
• Unusual occurrence of the
disease clearly in excess
of its normal expectation
• In a geographical location
• At a given point of time
20
15
10
5
0
Endemicity
Epidemic
1 2 3 4 5 6 7 8 9 10 11 12 13

4. What’s an epidemic?
• Unusual occurrence of disease or specific health related behaviour
in a community or region clearly in excess of expected numbers.
• An arbitrary limit of two standard errors from the endemic
frequency is used to define the epidemic threshold for common
diseases

5. What is an outbreak ?
• Occurrence of more cases of disease than expected
 in a given area
 over a particular period of time
 among a specific group of people
• Occurrence of two or more Epidemiologically linked cases of a
disease of outbreak potential
• A single case of a new emerging disease/ eradicated disease

6. Outbreak and epidemic:
A question of scale
• Outbreaks
 Outbreaks are usually limited to a small area
 Outbreaks are usually within one district or few blocks
• Epidemics
 An epidemic covers larger geographic areas
 Epidemics usually linked to control measures on a district/state wide
basis
• Use a word or the other according to whether you want to generate or
deflect attention

7. Levels of response to different triggers
Trigger Significance Levels of response
1 Suspected /limited outbreak • Local response by health worker and
medical officer
2 Outbreak • Local and district response by district
surveillance officer and rapid response
team
3 Confirmed outbreak • Local, district and state
4 Wide spread epidemic
Natural disaster
• Local, district, state and centre
5 Pandemic • International

8. Disease Trigger 1 Trigger 2
Malaria •Single case of smear positive in an area where
malaria was not present for a minimum of three
months
•Slide positivity rate doubling over last three
months
•Single death from clinically /microscopically
proven malaria
•Single falciparum case of indigenous origin in
a free region
•Two fold rise in malaria in
the region over last 3
months
•More than five cases of
falciparum of indigenous
origin
Polio Even a single case will trigger outbreak investigations
Plague Rat fall At least 1 probable case of
plague in community
Jaundice More than two cases of jaundice in different houses irrespective of age in a
village or 1000 population

9. Sources of information to detect outbreaks
EVENT-BASED SURVEILLANCE:
Rumour register : To be kept in standardized format in each
institution
Community informants : Private and public sector
Media : Important source of information, not to be neglected
CASE-BASED SURVEILLANCE:
Review of routine data : review the data from the routine surveillance
and check if it crosses threshold levels
Trigger events

10. Investigations of an outbreak of jaundice,
Rohtak
Recognition of cases and reporting:
• People recognized their own signs and symptoms ……. Reported to health
facility
• Local press published the reports and drew attention of civil and
administrative authorities
• Health workers played a marginal role
• Private practitioners also, did not report
• District authorities appeared on the scene quite late

11. Diseases requiring investigations
• Endemic diseases with a potential of causing focal or large outbreaks, e.g.
malaria, cholera, measles, viral hepatitis, meningococcal meningitis, etc.
• Diseases under eradication or elimination phase; even a single case of such
disease may be treated as an outbreak, e.g. poliomyelitis
• Rare but internationally important diseases with high case fatality rate and
with the potential of importation due to existence of conducive
epidemiological conditions e.g. yellow fever, avian influenza etc.
• Outbreaks of unknown diseases/syndromes

12. Early warning signals for an outbreak
 Clustering of cases
 Increases in cases or deaths
 Single case of disease of epidemic potential
 Acute febrile illness of an unknown aetiology
 Two or more linked cases of meningitis, measles
 Unusual isolate
 Shifting in age distribution of cases
 High vector density
 Natural disasters

13. Deciding whether to Investigate a Possible
Outbreak
• Severity of illness
• Number of cases
• Source / mode of transmission
• Availability of preventive & control measures
• Availability of staff & resources
• Public, political and legal concerns
• Public health program considerations
• Potential to affect others if the control measures are not taken
• Research opportunity

14. WHY SHOULD WE
INVESTIGATE OUTBREAKS?

15. The balance between investigation and control
while responding to an outbreak
Source & mode of transmission
Known Unknown
Causative
agent
Known Control +++
Investigate +
Control +
Investigate +++
Unknown Control +++
Investigate +++
Control +
Investigate +++
CONTROL AND PREVENTION MEASURES
• Are cases continuing to occur ?
• Is the outbreak just about over ?

16. RESEARCH OPPORTUNITIES
• Newly recognized disease
• define its natural history:
» Agent
» mode of transmission
» incubation period
» clinical spectrum
» characterize the populations at risks
» identify risk factors
• Well – characterized diseases
• assess control measures
• assess usefulness of new epidemiology and laboratory techniques

17. TRAINING
• Develop the following skills through practice and experience:
» Diplomacy
» Logical thinking
» Problem solving ability
» Quantitative skills
» Epidemiologic know-how
» Judgment

18. PUBLIC, POLITICAL or LEGAL
CONCERNS
• Sometimes override scientific concerns in the decision to
conduct an investigation
• Essential to be “responsibly responsive” even if the concern has
little scientific basis

19. PROGRAM CONSIDERATIONS
• Program Evaluation
» identify populations overlooked
» recognize intervention strategy failures
» identify changes in the agent or events beyond the
scope of the program

20. Importance of timely action:
The first information report
• Filled by the reporting unit
• Submitted to the District Surveillance Officer as soon as the
suspected outbreak is verified
• Sent by the fastest route of information available
 Telephone
 Fax
 E-mail

21. Steps for investigation

22. Unusual health event
No Yes
Is this an outbreak
Etiology, source &
transmission
known?
Does the hypothesis
fit with the facts?
Yes
Yes
No
No
Institute control measures
Further investigation
(clinical ,lab.,
epidemiological)
Describe outbreak in
terms of Place, time
and Person
Develop Hypothesis regarding
source, transmission, aetiology
and people at risk
Institute control measures
Special studies

23. Conducting an outbreak investigation
in 10 steps
• Step 1: Prepare for Field Work
• Step 2: Establish the Existence of an Outbreak
• Step 3: Verify the Diagnosis
• Step 4: Define and Identify Cases
• Step 5: Describe and Orient the Data
• Step 6: Develop Hypotheses
• Step 7: Evaluate Hypotheses
• Step 8: Refine Hypotheses
• Step 9: Implement Control and Prevention Measures
• Step 10: Communicate Findings

24. Check-list for investigation and rapid
containment of the outbreak
1) Preparation for field
2) Make provisional diagnosis and develop working case-definition
3) Confirm existence of an outbreak
4) Line-listing of cases
5) Management of cases
6) Rapid household/community survey for case finding
7) Entomological and environmental investigations
8) Laboratory investigations

25. Check-list for investigation and rapid
containment of the outbreak
9) Data analysis
10) Institution of control measures
11) Interim report
12) Final report
13) Follow-up of outbreak
14) Testing of hypothesis
15) Evaluation of outbreak management including investigations
16) Documentation and sharing of lessons learnt

26. STEP 1: PREPARE FOR FIELD
WORK

27. Preparation for Field Work
• Investigation
 Scientific knowledge--have it or get it!
 Supplies, equipment
 Assemble your team
• Administration
 Review local directives or plans
• Consultation
 Know your role
• Sample questionnaires
• Key community contacts
• Laboratory containers and collection
techniques
• Identify Outbreak Team
 Clinician /paediatrician
 Epidemiologist
 Microbiologist
 Laboratory workers
 Environmental health
specialists
 Local health department
 Other state agencies

28. Preparation for Field Work
• Before leaving for the field, the team leader(or members) should ensure
the following:
 Verify rumours and collect preliminary information about the
episode from the State or Central Health Authorities working in the
affected area over telephone or through e-mail.
 Make necessary technical, administrative and logistics arrangements
 As per the preliminary information, prepare an “Outbreak
Management Kit”.
 Brief members of RRT on purpose and their roles, responsibilities
and methods of self protection during outbreak investigation

31. STEP 2: ESTABLISH THE
EXISTENCE OF AN OUTBREAK

32. Make provisional diagnosis and develop
working case-definition
• Provisional clinical diagnosis : by examining (including history taking
and review of case records) a few current reported cases / recovered cases
• On the basis of clinical profile and case records, develop a “working case-definition”
which may specify area, population affected and duration of
episode
• To help in establishing the diagnosis, collect adequate number of
appropriate clinical samples of current/ recovered cases and their
contacts. Record the details on “Laboratory Form”

33. Case-definition
• A standard set of criteria for deciding whether, in this investigation, a
person should be classified as having the disease or health condition
under study.
• A case definition usually includes four components:
• clinical information about the disease,
• characteristics about the people who are affected,
• information about the location or place, and
• a specification of time during which the outbreak occurred

34. EXAMPLE: CASE DEFINITION
OUTBREAK OF S. TYPHI JURA, M-J, 1997
CONFIRMED
Clinical
• Diarrhoea (>2 liquid stools/ day)
or
• Fever >38°C (+one day)
Place & person
• resident in Jura or neighbourhood
Time
• Since 12 May 1997
Biological
• Identification of S . Typhimurium
PROBABLE
Clinical
• Diarrhoea (>2 liquid stools/ day)
or
• Fever >38°C (+one day)
Place & person
• resident in Jura or neighbourhood
Time
• Since 12 May 1997
Biological
• None, but contact with confirmed case

36. Investigations of an outbreak of jaundice,
Rohtak
Confirmation of diagnosis
Standard case definition applied:
• Acute febrile illness of short duration, (fever ) with malaise, anorexia,
followed by jaundice, hepatomegaly, and abdominal tenderness in right
upper quadrant, increase in ALT >2.5 times and serum bilirubin >2mg%.
• Limited number of blood samples drawn and tested in laboratory of
medical college, Rohtak to confirm the diagnosis
• Serological tests done through National Institute of Communicable
Diseases indicated HEV outbreak

37. Confirm existence of an outbreak
• Review clinical and laboratory records of the current and recovered cases
• Epidemiological linkages of suspected cases of “similar in nature”
• Compare the current situation (data) with the available data of the
corresponding period of past 2-3 years
 For a notifiable disease: health department surveillance records.
 For other diseases and conditions: find data from local sources such
as hospital discharge records, death (mortality) records, and cancer or
birth defect registries.
 If local data are not available: make estimates using data from
neighbouring states or national data

38. Confirm existence of an outbreak
Caution!
• Seasonal variations
• Notification artefacts
• Diagnostic bias (new technique)
• Diagnostic errors (pseudo-outbreaks)

39. What could account for the increase
in cases?
Real increase
• Increase in population size
• Changes in population
characteristics– due to
population movement e.g.,
harvesting season, fairs, etc.
• Random variation
• Outbreak
Artificial increase
• Changes in reporting
procedures– increase in
number of reporting units or
change in case-definition etc.
• Improvements in diagnostic
procedures
• Increased interest because of
local or national awareness
• Contamination of specimens

40. Outbreak confirmed 
Immediate control
measures?
Further
investigation?
- prophylaxis
- exclusion / isolation
- public warning
- hygienic measures
- aetiological agent
- mode of transmission
- vehicle of transmission
- source of contamination
- population at risk
- exposure causing illness

41. further investigations warranted
Epidemiologist
Laboratory specialist
Clinician
Outbreak confirmed,
Form Rapid
Response Team
Team coordinates
field investigation

42. Investigations of an outbreak of jaundice,
Rohtak
Establish the existence of an outbreak
People first:
• House to house survey was done in the affected areas in May 2000
• People interviewed ……. Confirmed that it was an unusual occurrence …..
Not witnessed in last ten years or so.
• Health institutions did not provide basic epidemiological data …..
Because of nonexistence of surveillance system

43. STEP 3: VERIFY THE
DIAGNOSIS

44. • Medical investigation - The physician / paediatrician clinically examines
the available cases (in the hospital or the community) and make a
clinical diagnosis.
• Laboratory investigation - The microbiologist performs appropriate lab
investigations. He advises on what samples are required, mode of
collection and method of transportation and also to which lab it has to
be sent. If the outbreak warrants entomological investigation should also
be done.
• Epidemiological investigation - The epidemiologist will look into the
epidemiological and environmental aspects of the outbreak. The basic
aim is to identify the source of the problem and the routes of
transmission.

45. STEP 4: DEFINE AND IDENTIFY
CASES

46. Line-listing of cases
• Using “working case-definition” record name, address, age, sex, status of
immunisation, symptoms, date of onset, recent travel history, treatment /
hospitalization, outcome of each case or other variables as may be
required etc. in the “line-list” format
• Active surveillance
• Passive surveillance

47. Management of cases
• Manage cases appropriately with the help of local clinical facilities to
prevent deaths.
• If indicated, cases should be managed in isolation to prevent further
transmission of infection.
• Ensure medical logistics i.e. sufficient quantities of essential drugs and
supplies etc.

48. Rapid household/community survey for
case finding
• Search more cases in the community by using working case-definition
• Record information on survey formats

51. Laboratory investigations
• Ensure proper collection, labelling, transportation and storage of clinical
samples
• Wherever rapid diagnostic tests are available, use them in the field or
send the specimens to the concerned laboratory for testing.
• Follow bio-safety precautions during collection and handling of
specimens
• Follow national and international guidelines for transportation of
specimens.

52. Entomological, environmental and
zoonotic surveys
• Assess the type and density of vector(s) for the possibility of vector-borne
disease outbreak
• Collect data on:
- Rainfall
- Humidity
- Temperature
- Drinking water supply
- Environmental sanitation
- Man-made situations like developmental/irrigation projects etc.
- Any health activity (intervention) taken up in recent past

53. Investigations of an outbreak of jaundice,
Rohtak
Laboratory investigations and confirmation
• District health authorities collected water samples
• Orthotolidine test : negative in one-third of samples
• Coliform count in laboratory : 3 out of 5 samples were unfit due to
unacceptable coliform count.

54. Investigations of an outbreak of jaundice,
Rohtak
Other observations
• Poor sanitary conditions
• Open field defecation practiced by 6.7% households
• 30.3% did not wash their hands before eating
• Drinking water stored in pitchers in 84% households
• Ladle used by only 27.4% individuals

55. STEP 5: DESCRIBE AND
ORIENT THE DATA

56. DEFINE THE POPULATION AT RISK
• Map of the area
• Get a detailed & current map of the area; if not available
prepare such a map
• Containing information concerning natural landmarks,
roads etc
• Dwelling units may designated by numbers
• Counting the population
• Denominator may be entire population or a subgroup
• Will help in much needed attack rates in various groups &
subgroups

57. Data Analysis
• Plot “Epidemic Curve” to describe the outbreak in terms of “time” (Time-analysis)
• Make maps and tables for describing place and person (Place and Person
analysis)
• Determine population at risk of infection
• Analyze rapid household survey data and calculate population-based
attack rates by age and sex groups
• Formulate a hypothesis which should include characteristics of affected
population, cause of disease, mode of transmission, incubation period,
genesis of outbreak etc.

58. Characterizing by time
• Time course of an epidemic is shown by drawing a graph of the number
of cases by their date of onset-- epidemic curve, or "epi curve”.......gives a
simple visual display of the outbreak's magnitude and time trend.
• Where we are in the course of the epidemic, and helps project its future
course.
• If the disease and its usual incubation period is known, probable time
period of exposure can be estimated and a questionnaire focusing on
that time period can be developed.
• The epidemic pattern can be interpreted—for example, whether it is an
outbreak resulting from a common source exposure, from person-to-person
spread, or both.

59. Examples of Epicurves
Common point source Common persistent source
6
5
4
3
2
1
0
1 2 3 4 5 6 7 8
10
9
8
7
6
5
4
3
2
1
0
1 2 3 4 5 6 7 8 9 10 11 12
12
10
8
6
4
2
0
Hours Days
1 2 3 4 5 6 7 8 9 10 11 12 13
cases
Common intermittent source
Days
Propagated source
10
9
8
7
6
5
4
3
2
1
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
cases
cases
cases
weeks

60. WEEKLY INCIDENCE OF JAUNDICE IN ROHTAK TOWN FROM
2
6
8
13
MARCH TO SEPTEMBER, 2000
22
31
42
32
37
19
12 12
20
18
10 10
24
15
11
9 8
6
8 7 6 5 4 3
45
40
35
30
25
20
15
10
5
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Cases
March April May June July August September
Weeks

61. Characterizing by place
• Assessment of an outbreak by place provides information on the
geographic extent of a problem and may also show clusters or patterns
that provide clues to the identity and origins of the problem.
• A simple and useful technique for looking at geographic patterns is to
plot, on a "spot map" of the area, where the affected people live, work, or
may have been exposed.

62. Drawing a spot map during an
outbreak investigation
• Rough sketch of the setting of
an outbreak
• One dot = One case
• Other locations of potential
importance are also recorded
• Does not adjust for
population density

63. Jind road
DISTRIBUTION OF
CASES OF VIRAL
Rtk Rly Stn
Vaish college
Shivaji colon
Janta colony
Naya Parav Kamala nagar
Sugar Mill Vijay Nagar
Hissar ROAD
JIND RLY LINE
GOHANA ROAD
HEPATITIS OUTBREAK IN
ROHTAK, 2000
Cases were distributed in 61 localities (400 cases).
272 cases(68%) clustered in 5 localities adjacent to each other and had
piped water supply from water works “2”.
Most affected locality was Janata Colony with reported127 cases

64. Characterizing by person
• Define such populations by personal characteristics (e.g., age, race, sex,
or medical status) or by exposures (e.g., occupation, leisure activities, use
of medications, tobacco, drugs). These factors are important because they
may be related to susceptibility to the disease and to opportunities for
exposure.
• Age and sex are usually assessed first, because they are often the
characteristics most strongly related to exposure and to the risk of
disease.

65. Investigations of an outbreak of jaundice,
Rohtak
Age and sex distribution
Sex distribution:
• Males = 66.5%
• Females = 34.5%
Age distribution:
• Children <= 14 years =22%
• 15- 59 years age = 77% (majority)
• > 60 years = 1%
Most house holds reported only single case.

66. AR & CFR OF VIRAL HEPATITIS OUTBREAK IN
ROHTAK, 2000
LOCALITY Population CASES AR Death CFR
Janata Colony 14420 127 0.88 2 1.6
Shivaji Colony 7625 66 0.80 0 0
Naya Parav 1856 33 1.78 1 3. 13
Kamla Nagar 3947 21 0.64 0 0
Vijay Nagar 4930 25 0.42 0 0
Other Localities 120000 128 0.10 0 0
Total 152778 400 0.33 3 0.75

67. Data Analysis
Person
Place
Time
Cases
25
20
15
10
5
0
1 2 3 4 5 6 7 8 9 10
1200
1000
800
600
400
200
0
0-4 '5-14 '15-44 '45-64 '64+
Age Group
Evaluate information
Pathogen? Source? Transmission?

68. STEP 6: DEVELOP
HYPOTHESIS

69. Hypothesis
• Supposition made from data analysis & interpretation.
» Characteristics of the population –
» Specific cause ( Source, Agent )
» Environmental factors -
» Expected outcome –
» Dose response relationship –
» Time response relationship –
• May be generated by-
 Considering what you know about the disease itself, or
 Talking to few of the case patients, or
 The descriptive epidemiology may provide useful clues that can be
turned in to hypotheses.

70. STEP 7: EVALUATE
HYPOTHESES

71. • Two approaches
• 1) comparison of the hypotheses with the established facts : when your
evidence is so strong that the hypothesis does not need to be tested.
• 2) analytic epidemiology, which allows to test your hypotheses : when the
cause is less clear
» Cohort studies
» Case-control studies

72. Cohort studies
• Best technique for analyzing an outbreak in a small, well-defined
population
• To identify the source of the outbreak from this information, you would
look for an item with:
 a high attack rate among those exposedand
 a low attack rate among those not exposed
 most of the people who became ill should have been exposed
• Calculate the mathematical association between exposure and illness
called the relative risk (produced by dividing the attack rate for people
whowere exposed by the attack rate for those whowere not exposed .)

73. Case-control studies
• Where the population is not well defined
• odds ratio—to quantify the relationship between exposure and disease.
This method does not prove that a particular exposure caused a disease,
but it is very helpful and effective in evaluating possible vehicles of
disease.
Testing statistical significance
• The final step in testing your hypothesis is to determine how likely it is
that your study results could have occurred by chance alone.

74. STEP 8: REFINE HYPOTHESES
AND CARRY OUT ADDITIONAL
STUDIES

75. • When analytic epidemiological studies do not confirm your hypotheses
• Even when your analytic study identifies an association between an
exposure and a disease, you often will need to refine your hypotheses. .
Sometimes you will need to obtain more specific exposure histories or a
more specific control group.
• When an outbreak occurs, whether it is routine or unusual, you should
consider what questions remain unanswered about the disease and what
kind of study you might use in the particular setting to answer some of
these questions.

76. STEP 9: IMPLEMENTING
CONTROL AND PREVENTION
MEASURES

77. Institution of control measures
• Based on clinical, epidemiological and entomological findings,
implement appropriate control measures to prevent further
spread of the disease
• Institution of control measures and management of cases should
not be delayed pending laboratory confirmation of diagnosis

78. Investigations of an outbreak of jaundice,
Rohtak
Interventions
• Super chlorination of water done
• Home chlorination where ever OT test was negative
• Boiling of water accepted by 15% of families
• People educated to wash hands
• Public health department identified leakage and corrected those; choked
sewer was attended to urgently
• Health workers , anganwadi workers played pivotal role in inter-personal
communication

79. STEP 10: COMMUNICATE
FINDINGS

80. Daily situation updates
• During the period of the outbreak the nodal MO should continue to
give daily situation updates of the outbreak to the next level.
• This should continue even when the epidemic investigation team has
started its investigation
• Updates include the list of new cases, lab results received, any new
findings, any containment measures taken etc.
• Continues till the end of the outbreak

81. Interim report
• RRT submits an interim report within one week of starting their
investigation, response and control activities
• The report should cover
» verification of the outbreak,
» total number of affected cases/ deaths,
» time, person, place analysis,
» management of the patients,
» likely suspected source,
» immediate control measures implemented, etc.
• Also has provisional hypothesis of the causation of the outbreak and
comments/recommendations, if any, including whether any further
outside help is necessary.

82. Monitoring the situation
• The DSO should monitor the situation on a daily basis and give
feedback to the RRT as well as feed forward to the State.
• The main points to monitor are:
• The trends in the cases and deaths.
• The containment measures that are being implemented
• Drugs / vaccine stock
• Logistic issues – communications, vehicles,
• Community involvement
• Media response
• This should continue till the outbreak is officially declared to be over.

83. Declaring the outbreak over
• Role of the district surveillance officer
• Criteria
 No new case during two incubation periods since onset of last
case
• Implies careful case search to make sure no case are
missed

84. Evaluation of outbreak management
including investigations
• Once the outbreak is over, request the local health authority to
evaluate following aspects:
• Genesis of the outbreak
• Early or late detection of outbreak
• Preparedness for the outbreak
• Management of the outbreak
• Control measures undertaken and their impact

85. Final report
• Within 10 days after the outbreak has ceased.
• Comprehensive and give a complete picture of the outbreak,
 the precipitating factors,
 the evolution of the epidemic,
 description of the persons affected,
 time trends, areas affected and direction of spread of the epidemic.
• Complete details of lab results
• Feedback from the report should be shared with the lower levels and also
other districts.
• Publication in a journal
Suggested Format for Writing Outbreak Investigation Report

88. Follow-up of outbreak
• Follow-up visits are important during the declining phase of an
outbreak to:
• Detect last case(s)
• Detect and treat late complications (if any)
• Complete the documentation of the outbreak

89. Documentation and sharing of lessons
learnt
• Organize post-outbreak seminar
• Provide feedback to State and district RRTs
• Develop case studies on selected outbreaks for training RRT
members

90. Constraints of field outbreak investigation
• Urgency to find source and prevent cases
• Pressure for rapid conclusion
• Statistical power often limited
• Media reports may bias interviewees
• Pressures because of legal liability
• Pressures because of financial liability
• Delays lead to limited human or environmental samples for testing

91. Preparedness for Prevention and Control
for Future Outbreaks
• Strengthen routine surveillance system
• Identify a nodal officer at the state and district levels
• Constitute an inter-disciplinary Rapid Response Team (RRT) at
state/district levels
• Train medical and other health personnel
• List the laboratories at regional /state/district levels
• List the hospitals (government/private/NGO) with level and type of
services available in the area

92. Preparedness for Prevention and Control
for Future Outbreaks
• List “high-risk” pockets in the rural / urban areas
• Establish a rapid communication network
• Undertake IEC activities for community participation
• Ensure that essential supplies are available at the peripheral health
facilities and buffer stocks are maintained at the district level
• Set-up an inter-departmental committee, including Non-Government
Organizations (NGOs) for inter-sectoral coordination

93. The reality….
Info:
Outbreak
suspected
time
Confirmation
Confirm Diagnosis
Form Outbreak
Control Team
Site visit
Case definition
Organize Data
Descripitve
Epidemiology
Line list
Recommendations
Analytic
Epidemiology
Control measures
Report
Publication

94. Thank you

95. General framework of an outbreak
investigation report
1. Executive summary
 < one page or < 300 words
 Structure with subheadings
2. Background
 Territory, origin of the alert, time of occurrence, places, official staff met
3. Methods used for the investigation
 Epidemiological methods
• Case definition
• Case search methods, data collection
• Analytical studies if any
• Data analysis
 Laboratory methods
 Environmental investigations

96. General framework of an outbreak
investigation report
4. Major observations / results
 Epidemiological results (population at risk, time, place and person characteristics)
 laboratory diagnosis
 Environmental investigation results
 Current status of transmission, control measures adopted/ initiated
5. Conclusion: Genesis of outbreak (Diagnosis, source, vehicles)
6. Recommendations

97. Annexes of the report
1. TIME: Epidemic curve
2. PLACE: Map
 Spot map
 Map of incidence by area
3. PERSON: Table of incidence by age and sex
4. Analytical study results if any

99. Control measures for an outbreak
• General measures
 Till source and route of transmission identified
• Specific measures, based upon the results of the investigation
 Agent
• Removing the source
 Environment
• Interrupting transmission
 Host
• Protection (e.g., immunization)
• Case management

100. Specific outbreak control measures
• Waterborne outbreaks
• Access to safe drinking water
• Sanitary disposal of human waste
• Frequent hand washing with soap
• Adopting safe practices in food handling
• Vector borne outbreaks
• Vector control
• Personal protective measures
• Vaccine preventable outbreaks
• Supplies vaccines, syringes and injection equipment
• Human resources to administer vaccine
• Ring immunization when applicable

101. Common Interventions Used to
Control an Epidemic
• Control the source of the pathogen. Remove the source of contamination (e.g., discard
contaminated food), remove persons from exposure (e.g., keep people from being
exposed to mosquito bites to prevent West Nile virus encephalitis), inactivate or
neutralize pathogen (e.g., disinfect and filter contaminated water) and/or treat
infected persons (e.g., treat pregnant patients with AIDS to avoid transmission to the
baby).
• Interrupt the transmission. Sterilize or disinfect environmental sources of
transmission (e.g., milk, water, air), control mosquito or vector transmission using
skin repellents, improve personal sanitation (e.g., washing hands before eating).
• Control or modify the host response to exposure. Immunize the susceptible hosts, use
prophylactic chemotherapy, modify behaviour or use a barrier (e.g., prevent exposure
to mosquito bites by wearing protective clothing and repellents).

102. 3. Monitoring the situation
• Trends in cases and deaths
• Implementation of containment measures
• Stocks of vaccines and drugs
• Logistics
 Communication
 Vehicles
• Community involvement
• Media response

103. Managerial aspects of outbreak response
• Logistics
 Human resources
 Medicines
 Equipment and supplies
 Vehicle and mobility
 Communication channels
• Information, education and communication
• Media
 Daily update

104. Reports
• Preliminary report by the nodal medical officer (First information
report)
• Daily situation update
• Interim report by the rapid response team
• Final report

105. Points to remember
1. Outbreaks cause suffering, bad publicity and cost resources
2. Constant vigil is needed
3. Prompt timely action limits damage
4. Emphasis is on saving lives
5. Don’t diagnose every case once the etiology is clear
6. Management of linked cases does not require confirmation
7. The development of an outbreak is followed on a daily basis
8. Effective communication prevents rumours
9. Use one single designated spoke person
10. Learn lessons after the outbreak is over