8/7/2019 4.02 Epidemic Investigation

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Definition of Outbreak Occurrence of more cases of disease than expected in

a given area among a specific group of people over aparticular period of time

Two or more linked cases of the same illnessObjectives of Outbreak Investigations

To determine the cause of the outbreak To control ongoing outbreaks To prevent future outbreaks To provide statutorily mandated services To strengthen surveillance at local level To advance knowledge about a disease To provide training opportunities

Specific Demands when Investigating Outbreaks Unexpected event Need to act quickly Need for rapid control Work carried out in the field

Steps of an Outbreak Investigation Confirm outbreak and diagnosis Case definition and identification Descriptive data collection and analysis Develop hypothesis Analytical studies to test hypotheses Special studies Implementation of control measures Communication, including outbreak report

Case Definition Standard set of criteria for deciding if a person should

be classified as suffering from the disease underinvestigation.

Clinical criteria, restrictions of time, place, person Simple, practical, objective Sensitivity versus specificity

Ex.Patient older than 5 years with severe dehydration or dying of

acute watery diarrhea in townX between 1 June and 20 July

2006

Examples of Case Definition: Possible

Patient with severe diarrhea

Probable Patient older than 5 years with severe

dehydration or dying of acute waterydiarrhea in town x between 1 June and20 July 2006

Confirmed Isolation of Vibrio cholerae from stool of

patient

Control the Source of Pathogen Remove source of contamination Remove persons from exposure Inactivate / neutralize the pathogen Isolate and/or treat infected persons

Interrupt Transmission Interrupt environmental sources Control vector transmission Improve personal hygiene

Modify Host Response Immunize susceptibles Use prophylactic chemotherapy

At the End Prepare written report Communicate public health messages Influence public health policy Evaluate performance

Cessation of an outbreak occurs when there is:

- elimination of source of contamination- interruption of transmission- reduction/exhaustion of susceptibles- modification of the effect of primary pathogen

An investigator should have knowledge on thefollowing:

various types of etiologic agents and the resultantdisease

epidemiological characteristics of outbreaksassociated with different etiologic agents of resultantdiseases

clinical symptoms of resultant diseases environmental and food sanitation practices sources of exposure which are vulnerable to

contamination with an infectious or chemical agent laboratory test available to determine causative agents read/search for additional data on studies, prevention

and control

EPIDEMIC INVESTIGATION

Lecturer: Dr. CollaoDate of lecture: January 25, 2011Transcriptionist: TransMistress Razeille

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