3/5/2020 I have nothing The Nuts and Bolts of an Outbreak Investigation to disclose. Robert Kosnik, MD Professor of Medicine, Medical Director, Occupational Health Services March 5, 2020 Investigation Fundamentals Angiosarcoma of the Liver Case (Definition) Disease: Angiosarcom a Exposure Exposure: Vinyl Chloride Association: Veteran em ployees w ith at least 1 2 years of experience & w orked as “pot cleaners” Association I nitially observed by John Creech MD, the plant physician, w ho realized through careful history-taking that they w orked in the sam e departm ent of the plant. Block BJ, “Angiosarcom a of the Liver Follow ing Vinyl Chloride Exposure”, JAMA. 1974; 229(1): 53-54. 1
3/5/2020 What is an Outbreak What is a Cluster An outbreak or an epidem ic is the A cluster is an aggregation of cases in occurrence of more cases of disease a given area over a particular period than expected in a given area or among without regard to whether the number a specific group of people over a of cases is more than expected. particular period of time. Usually, the cases are presumed to have a common This aggregation of cases seems to be cause or to be related to one another in unusual, but frequently the public (and some way. sometimes the health agency) does not know the denominator. Steps of an Outbreak Bradford Hill Criteria Investigation Strength of association Confirm the diagnosis Consistency across studies Determine the existence of an outbreak Specificity Identify and count cases Temporality Orient the data in terms of person, place, Biological gradient (dose-response) and time Biological plausibility Develop and test hypotheses Plan for more systematic studies Implement and evaluate control measures Communicate findings 2
3/5/2020 Issues Unique to JOHN SNOW AND THE BROAD STREET PUMP: 150 YEARS OF EPIDEMIOLOGY Occupational Outbreak By John Snow - Published by C.F. Cheffins, Lith, Southhampton Buildings, London, England, Investigations Diagnosis Workplace access Outbreak Identify cases “Healthy participant” effect Data (T ime, Place) Current vs. former workers Hypothesis Plan study Employed vs. contingent workers Implement Exposure assessment Evaluate Competing interests Communicate A skewing of data in randomized medical studies that occurs when healthy participants are less likely to drop out of the study than sicker patients. Wikipedia Potential Investigators Potential Stakeholders Clinicians Industry Academic researchers, consultants Labor Local and state health departments Government Occupational Safety and Health Insurers Administration (OSHA) Suppliers National Institute for Occupational Safety and Downstream users Health (NIOSH) 3
3/5/2020 Epidemiologic Steps of an Skin Disorder in Electronic Store Outbreak Investigation An outbreak of skin disorders was noted by the primary care physician Prepare for field work responsible for the health care of 52 employees in an electronics store. Establish the existence of an outbreak The cases occurred after termite treatment of the store, and the Verify the diagnosis breakdown of the air ‐ conditioning system in several areas in the store. Construct a working case definition Investigations were initiated to allay worker concern that the chemicals Find cases systematically and record information used for termite treatment (in particular, arsenic trioxide) were responsible for the outbreak. Perform descriptive epidemiology 9 of the 52 workers were found to have heat rash (miliaria rubra). 21% Develop hypotheses (7) of workers who worked in non ‐ air ‐ conditioned areas had heat Evaluate hypotheses epidemiologically rashes, as compared to 11% (2) of workers who worked in As necessary, reconsider, refine, and re-evaluate hypotheses air ‐ conditioned work zones. 2 workers had contact dermatitis due to exposure to greaseless lubricant, and 8 other workers had a Compare and reconcile with laboratory and/ or environmental non ‐ work ‐ related skin disorder. Indoor wet bulb globe temperature studies index measurements in the non ‐ air conditioned areas were within Implement control and prevention measures threshold limit values, but ventilation in these areas was very poor. 2 environmental samples had non ‐ detectable limits of arsenic. Initiate or maintain surveillance Communicate findings Principles of Epidemiology in Public Health Practice, Third Edition Contact Derm atitis, Koh, D; Volum e 3 2 , I ssue 6 , June 1 9 9 5 , Pages 3 2 7 -3 3 0 An Introduction to Applied Epidemiology and Biostatistics Infectious Agent Specific Definitions How to Respond Method of Transmission to an Outbreak: Case, Contact, Contact of Contact Self-Monitoring for Symptoms Level of Isolation (Social Distancing) When in the Midst Type of Quarantine (Movement Restrictions) of that Outbreak Type of Exposure – Protected or Unprotected 4
3/5/2020 Transmission of an Infectious Agent Transmission of an Infectious Agent EXPOSURE DIAGNOSIS EXPOSURE DIAGNOSIS ## Days ## ## Days ## Days Days INCUBATION PRODROME SYMPTOMS RESOLUTION INCUBATION PRODROME SYMPTOMS RESOLUTION INFECTIVITY Time Time Transmission of an Infectious Agent Transmission of Small Pox EXPOSURE DIAGNOSIS EXPOSURE DIAGNOSIS ## Days ## 12 Days 1 - 4 Days Days INCUBATION PRODROME SYMPTOMS RESOLUTION INCUBATION SYMPTOMS RESOLUTIO N INFECTIVITY INFECTIVITY 21 Time Time Days HCW A HCW B HCW C HCW A HCW B HCW C EXPOSURE EXPOSURE EXPOSURE EXPOSURE EXPOSURE EXPOSURE 5
3/5/2020 Transmission of Pandemic Influenza Transmission of SARS CoV - 1 EXPOSURE DIAGNOSIS EXPOSURE DIAGNOSIS 24 – 72 0 Days 4 - 10 Days 0 Days hours INCUBATION PRODROME SYMPTOMS RESOLUTION INCUBATION SYMPTOMS RESOLUTIO N INFECTIVITY INFECTIVITY 3 Days Time ?? Days Time HCW A HCW B HCW C HCW A HCW B HCW C EXPOSURE EXPOSURE EXPOSURE EXPOSURE EXPOSURE EXPOSURE Transmission of SARS CoV - 2 EXPOSURE DIAGNOSIS 14 Days 0 Days INCUBATION SYMPTOMS RESOLUTIO N INFECTIVITY ?? Days Time HCW A HCW B HCW C EXPOSURE EXPOSURE EXPOSURE 6
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