20 FCM2 - Outbreak

S4 Lec 20: Outbreak Investigation (not lectured) Draby Dra. Moderes

Definition of Outbreak  Occurrence of more cases of disease than expected in a given area among a specific group of people over a particular period of time or  Two or more linked cases of the same illness Objectives 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 under investigation.  Clinical criteria, restrictions of time, place, person  Simple, practical, objective  Sensitivity versus specificity

---  --Example. Patient older than 5 years with severe dehydration or dying of acute watery diarrhea in town “X” 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 watery diarrhea in town “x” between 1 June and 20 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 susceptible  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 susceptible - modification of the effect of primary pathogen An investigator should have knowledge on the following:  various types of etiologic agents and the resultant disease

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epidemiological characteristics of outbreaks associated with different etiologic agents of resultant diseases 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 Coverage of Exam:     

Poster making and guidelines (5pts) Outbreak (20 pts) NCD (25pts) CD (25pts) Screening Test (25pts)

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