| Epidemiology Program: Outbreak Investigation |
| Epidemiology |
| Epidemiology, cont. |
| Epidemiology: Interpretation of Results |
| Attributes of a Public Health Surveillance System |
| Confidentiality |
| Basic Structure of Public Health Surveillance |
| Factors Affecting Occurrence of Infection |
| How Communicable Diseases are Transmitted |
| General Principles of the Epi Field Investigation |
| Steps in Conducting a Field Investigation |
| Confirm the Diagnosis |
| Confirm the Existence of an Outbreak |
| Determine the Number of Cases |
| Develop an Initial Case Definition |
| Case Definitions |
| “Describe” the Outbreak |
| Descriptive Epidemiology |
| Person: Frequency Tables
|
| Place: Spot Maps |
| Place: Common Exposure Location |
| Place: Common Exposure Location (cont.) |
| Point-Source Exposure |
| Ongoing Exposure |
| Secondary Exposures |
| Identify Persons At Risk |
| Develop a Hypothesis |
| Hypothesis |
| Case Definition vs. Hypothesis |
| Compare Hypothesis to Facts |
| Conduct an Analytical Study |
| Analytical Epidemiology |
| Measures of Association Between Exposure & Disease |
| Cohort Studies |
| Attack Rate: Measure of Occurrence |
| Estimating Risks Associated with “Exposure” |
| Using the 2 by 2 Table to Calculate Relative Risk |
| Case-Control Studies |
| Odds Ratio from Case-Control Studies |
| Using the 2 by 2 Table to Calculate Odds Ratio |
| Validity of Findings |
| Examples of Bias |
| Confounding |
| Evaluating the Role of Chance |
| Evaluating the Role of Chance, cont. |
| P Values and Confidence Intervals, Example 1 |
| P Values and Confidence Intervals, Example 2 |
| P Value: Effect of Sample Size |
| P Value: Effect of Sample Size, cont. |
| P Value: Effect of Sample Size, cont. |
| The Significance of “Significance” |
| Implement Control & Prevention Measures |
| Outbreak Investigation and Control |
| Foodborne Diseases |
| Foodborne Disease: Factors Affecting Epidemiology & Surveillance |
| Foodborne Diseases: Scope |
| Transmission of Foodborne Diseases |
| Foodborne Disease Agents |
| Non-Foodborne Routes of Disease Transmission |
| A Foodborne Outbreak of Shigellosis |
| Notification |
| Case Ascertainment |
| Interviews |
| Case Definition |
| Outbreak Cases: Patrons |
| Outbreak Cases: Staff |
| Estimated Attack Rate |
| Epidemic Curve |
| Foodborne Disease Outbreak |
| Exposure Assessment |
| Exposure Assessment, cont. |
| Exposure Assessment, cont. |
| Lab Results: Pulsed-Field Gel Electrophoresis |
| Environmental Findings |
| Conclusions |
| Policy Implications |
| Outbreak of Giardiasis: Milton, MA, 2003 |
| Giardiasis: Epidemiology
|
| Giardiasis: Epidemiology, cont. |
| Giardiasis: Clinical |
| Background: Outbreak |
| Background: Country Club |
| Water Supply for Milton |
| Objectives of Investigation |
| Method: Retrospective Cohort Study |
| Questionnaire |
| Case Definitions |
| Results of Questionnaire |
| Breakdown of Cases (n = 149) |
| Symptoms of Cases (N = 149) |
| Symptoms of Cases (N = 149) |
| Duration of Symptoms for Cases (n = 80) |
| Age and Sex |
| Percent Cases by Age Group |
| Epidemic Curve (n = 135) |
| Newspaper Heading |
| Epidemiology Program: Outbreak Investigation: Slide 97 |
| Further Case Definitions |
| Rationale for 60-Day Time Frame
for Secondary Cases before October 5 |
| Cases by Status |
| Epidemic Curve (n = 135) |
| Possible Fecal Shedding |
| Risk Factors for Illness Among
Primary Cases (N = 30) |
| Primary Cases (exposure to pools) |
| Stratified Analysis: Kiddy Pool Exposure and Giardiasis by Age Group |
| Stratified Analysis: Age Group and
Giardiasis by Kiddy Pool Exposure |
| Dose Response |
| Household-Level Risk Factors |
| Recommendations |
| Follow-Up |
| Confirmed Cases of Giardia, Milton, 1999-2004 |
| Conclusions |
| A Foodborne Outbreak of Hepatitis A |
| Notification |
| Initial Investigation |
| Initial Investigation |
| Initial Investigation |
| Initial Investigation |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Hepatitis A Cases Associated with Marshfield Outbreak February-March 2004 |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Initial Investigation, cont. |
| Analytical Investigation |
| Analytical Investigation, cont. |
| Analytical Investigation, cont. |
| Analytical Investigation, cont. |
| Analytical Investigation, cont. |
| Restaurant 4 Odds Ratio |
| Restaurant 4 Odds Ratio |
| Restaurant 4 Odds Ratio |
| Restaurant 4 Odds Ratio |
| Restaurant 4 Odds Ratio |
| Restaurant 4 Odds Ratio |
| Further Investigation |
| Further Investigation |
| Further Investigation |
| Further Investigation, cont. |
| Further Investigation, cont. |
| Further Investigation, cont. |
| Control & Prevention |
| Tularemia: Martha’s Vineyard, Massachusetts Summer 2000 |
| Tularemia |
| Clinical Presentation |
| Tularemia on Martha’s Vineyard |
| Recognition of the Outbreak, July 2000 |
| Methods |
| Case Definition |
| Case-Control Study – Methods |
| Environmental Investigation |
| Results |
| Pneumonic Tularemia, By Week of
Illness Onset – Martha’s Vineyard, 2000 |
| Characteristics of Cases and Controls,
MV, 2000 |
| Characteristics of Cases and Controls, MV, 2000, cont. |
| Time Spent Outdoors - Martha’s Vineyard, 2000 |
| Logistic Regression |
| Environmental Results |
| Environmental Results |
| Conclusions |
| Limitations |
| Recommendations |
| Challenges in Recognizing a Bioterrorist Attack |
| Some Indicators of Bioterrorism Events |
| Public Health Bioterrorism Surveillance Plan |
| Early Detection of a BT Event: Finding a Zebra Among Horses |
| Salmonellosis in Oregon, 1984 |
| Salmonellosis in Oregon, cont. |
| Salmonellosis in Oregon, cont. |
| Salmonellosis in Oregon, cont. |
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