investigation of an epidemic by taking ebola as an example....................................................................................................................................................................................................................................................................

1. INVESTIGATION OF AN EPIDEMIC
21.SHAZIA FAZAL
22.G.PRATIBHA
23.G.ANUSHA
24.J.GOWTHAMI
25.G.SUMANTH

2. WHAT IS AN EPIDEMIC.. ?
The “unusual” occurrence of
disease or other health related
events in a community or region
clearly in “excess of expected
occurrence”
AGENT
HOST
ENVIRO
NMENT
Any disease comes from a break in
the balance between the host, the
environment and the agent

3. ENDEMIC- The constant presence of a disease within
a given geographic area or population group
EPIDEMIC – The unusual occurrence of a disease in a
community clearly in excess of expected occurrence
PANDEMIC-An epidemic occurring worldwide, or over
a wide geographic area, crossing international
boundaries

4. OBJECTIVES OF AN EPIDEMIC
INVESTIGATION
Verify and recognize the magnitude of epidemic
Diagnose the agent
Identify the source and modes of transmission
Factors responsible for occurrence of epidemic
Formulate preventive and control measures

5. HOW TO INVESTIGATE…?
1) Prepare for field work
2) Verification of Diagnosis
3) Conformation of existence of an Epidemic
4) Defining the population at risk
5) Rapid search for all cases and their characteristics
6) Perform Descriptive Studies
7) Perform Analytical Studies
8) Evaluation of Ecological factors
9) Control and Preventive measures
10)Report Writing & maintain Surveillance

6. 1. PREPARE FOR FIELD WORK
•Set a Rapid response team
•Research the disease
•Make administrative
arrangements
•Identify & arrange for
resources
•Develop communication strategies for team, hospital
employees& public
Head of the state in affected countries declared the EBOLA outbreak as a
national emergency. Set up a rapid response team including health care workers,
lab technicians, cleaning staff, burial personnel & others

7. 2.VERIFICATION OF DIAGNOSIS
•Clinical examination of persons
who are affected
•Send the samples for Lab
Investigations
Diagnosisof Ebola
Antigen detection ELISA
Reverse transcriptase
polymerase chain reaction

9. 3.CONFIRMATION OF EXISTENCE OF AN EPIDEMIC
• Comparing the
disease frequency
during the
same period of
previous year

10. 4.DEFINING THE POPULATION AT RISK
Obtain a map of the area with
information concerning natural
landmarks, roads and dwelling units
Counting the population-use
this population as denominator
in indicators calculation

11. 5.RAPID SEARCH FOR ALL CASES AND THEIR
CHARACTERISTICS
Done under three levels:-
• Medical survey: Define case and identify the cases
i. who have sought medical care
ii. who have not sought medical care
iii. those possibly exposed to risk
• Epidemiological case sheet: Ensure completeness
and consistency of data collection
• Searching for more cases: Reveals additional cases
and person-to-person spread

12. 6.PERFORM DESCRIPTIVE STUDIES
•Describing the disease by-
 When is the disease occurring ?
Time distribution
 Where is the disease occurring ?
Place distribution
 To Whom is the disease occurring ?
Person distribution

13. Step-6 continued
•Measurement of disease
•Comparing with known indices
•Formulation of an etiological
hypothesis

14. 7.PERFORM ANALYTICAL studies
•Comprise two distinct types
 Case control study
measure of association=odd’s ratio
 Cohort study
measure of association=relative risk
• Designed to assess exposure among ill and non-ill
• Test the etiological hypothesis

15. 8.Evalution of ecological factors
• Factors which have made the epidemic possible should be
investigated
•USE:-To know Source of infection, Reservoir & Modes of
transmission
• Include Water supply-e.g.:-Cholera
Atmospheric changes-e.g.:-The Great Smog
Population dynamics of insects-e.g.:-Malaria
•Ebola viral disease primarily occur near tropical rain forests
•Fruit bats are believed to carry and spread Ebola virus
•Hunting & consumption of bush meat-spreads the virus to humans

16. 9.cONTROL AND PREVENTIVE MEASURES
• General measures
Till source and route of transmission
identified
• Specific measures :
 Reservoir or Source
Removing the source
 Modes of Transmission
Interrupting the transmission
 Host
Protection(e.g. immunisation)
Case management
PreventionofEbola infection
 Avoid bush meat
Isolation and avoid contact
with infected people
Follow barrier nursing
precautions
Don't handle remains
Avoid areas of known
outbreaks
 Airport screening of all
passengers
Quarantine

17. STEP-9.CONTINUED
•Early diagnosis and supportive treatment of
Ebola viral disease decreases case fatality rate
•Supportive treatment includes
1.Balancing fluids and electrolytes
2.Maintaining oxygen levels
3.Control bleeding
4.Maintaining blood pressure
5.Treating other infections
•Immunisation : vaccine under trials

18. 10.REPORT WRITING
Report should include
Introducing the identification of epidemic
Methods, data collection ,analyses ,and
interpretations for environmental, laboratory and
epidemiological methods
Results- descriptive as well as analytical
Implemented preventive and control measures and
their effectiveness
Recommendations regarding future surveillance and
control
Communicate findings with disease control
programs , media & public

19. SURVEILLANCE
Def: “the continuous scrutiny of the factors
that determine the occurrence and
distribution of disease”
Sentinel surveillance: For identifying missing
cases
Objectives:
Evaluate interventions and control
measures
Formulate recommendations

20. EPIDEMIC INVESTIGATION
DETECT-A possible epidemic
FIND Cases in an epidemic
GENERATE Hypotheses through interviews
TEST Hypotheses through analytical studies and
laboratory testing
SOLVE Point of contamination and original source of
epidemic vehicle
CONTROL Epidemic through recalls, facility
improvement and industry collaboration
DECIDE An epidemic is over
Not finding
associations
If cases stop
If cases continue

21. TAKE HOME MESSAGE
 Respond to early warning symptoms
 Investigate the epidemic:
• To decrease morbidity and mortality
rate of disease
• To cease the disease as a public health
problem

22. “You Are Safer
When Everyone Is
Educated”

23. REFERENCES
• Park’s textbook of Preventive and Social medicine, 22e
• Fact sheet N 103 on Ebola viral disease by world health
organisation-WHO
• Page published on Ebola outbreak by Centre for disease
control and prevention-CDC
• Harrison’s principles of Internal Medicine ,18e
• Page on ebola by mayoclinic.org
• Ebola outbreak video from you tube
• European centre for disease control-ECDC