Outbreak Detection and Investigation 1.A key public health function 2.Multi-disciplinary, but the epidemiologic component/approach is central 3.Requires a thoughtful, systematic approach 4.Requires well-trained investigators 5.Often poses substantial threat of economic harm and legal liability to individuals and companies 6.Typically occurs under a spotlight and requires excellent communication with decision-makers, the media, and the general public

Reasons why Outbreak Detection and Investigation are Important Public Health Functions 1.Terminate the outbreak/prevent new cases 2.Prevent future outbreaks 3.Gain knowledge about a disease, whether “new” or “old” 4.Reassure the public 5.Teach/learn epidemiology

Outbreak Detection and Investigation 1.The disease may be “new” or “old” 2.The causative agent may be known or unknown at the time of the investigation 3.The etiology of the disease may be an infectious agent, a chemical toxin, a nutritional deficiency, some other type of agent, or a combination of agents

Components of an Outbreak Investigation Case Definition Confirmation of Cases Case Finding Establish the Baseline/Determine if there is an Outbreak Describe Epidemiologic Features (time, place, person) Hypothesis Generation Hypothesis Testing Implementation of Control Measures Effective Communication Collection of Appropriate Specimens (environmental and clinical) Establish the Etiology

How do Epidemiologic Studies Done as Part of an Outbreak Investigation Differ from “Normal” Epidemiologic Studies? 1.Time/political pressure; speed is important 2.Primary purpose typically is to implicate a source rather than give a precise estimate of a risk ratio 3.Underlying “true” risk ratio is somewhere between enormous and infinite 4.Sample size/power calculations are rarely, if ever done

How Do Epidemiologists Learn About the Existence of Outbreaks? Patients/Families (e.g. Lyme disease) Clinicians (e.g. Legionnaires’, TSS, AIDS) Laboratorians Surveillance Media Reports (SARS)