Communicable Disease Epidemiology

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Communicable Disease Epidemiology Public Health
Surveillance An Overview

• Amy D. Sullivan, PhD, MPH
• Epidemiologist
• Multnomah County Health Dept.

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• Unlike a forest fire, in a bioterrorism (BT)
  event

Population at risk!

• Seeing the fire requires capturing
  epidemiologic data
• Responding requires using that data

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Topics in Presentation

• Basic principles
• Communicable disease epidemiology
• Public health surveillance
• Disease and outbreak reporting (local, state, and
  federal roles)
• Adapting for Incident Command System

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Basic Principles
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Epidemiologic Science

• Disagreement and confusion about basic ideas in
  epidemiology do not necessarily attest to the
  thick-headedness of epidemiologists a more
  charitable interpretation is that the basic
  ideas fundamental to this new science have not
  yet displaced traditional thinking.
• Rothman and Greenland, Modern Epidemiology

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What Is Epidemiology?

• Studying the distribution determinants of
  health-related states in specific populations to
  control health problems
• Usually human, but veterinary too
• Diseases or conditions
• Demand a set of actions as outcome

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Sub-Specialties

• Chronic
• Environmental
• Social
• Reproductive
• Infectious disease
• Acute Communicable
• Chronic Communicable

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Doing Epi

• Assess patterns of disease in populations
• Identify potential risks for disease
• Decrease/eliminate risk of disease
• Describe disease in population by Person, Place,
  and Time

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Person

• How many
• Clinical characteristics
• Medical history
• Immunization status
• Demographic characteristics
• Age, sex
• Race/ethnicity/culture

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Place and Time

• Place
• Geographic clustering
• Association with a point source
• Time
• Clustering in time
• Rate of development of new cases

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Epidemiologic Triad
Host
Agent
Environment
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Epidemiologic Triad
Host
Agent
Person Place Time
Environment
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Epidemiologic Triad
Agent
Host
Environment
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Epidemiology in Public Health Practice

• Public Health Surveillance
• Outbreak illness cluster investigation
• Special studies
• Resolve issues of detection bias or small numbers
• Program design evaluation

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Public Health Surveillance

• ongoing systematic collection, analysis,
  interpretation, and dissemination of data on
  health-related events to reduce morbidity and
  mortality and to improve health

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Passive vs. Active

• Passive Surveillance
• Wait for reports to arrive
• Active Surveillance
• Go out and collect information
• Example Medical record reviews

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Purposes of Surveillance

• Allow assessment of health status of a given
  population
• Provide quantitative basis to
• Set priorities
• Define strategies objectives for action
• Evaluate interventions/programs/ outcomes

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How Surveillance is Used

• Routine Surveillance
• Detect cases of disease of public health
  significance
• Detect outbreaks and illness clusters
• Event-specific surveillance
• Monitor progression of event
• Assess utility of intervention

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Outbreaks and Clusters

• Unusual amount of illness in a given population
  at a given time
• Influenza
• In 1 week, deaths due to pneumonia influenza
  (122 U.S. cities) exceeds 8.1
• Foodborne Illness
• Persons from 2 households share a specific meal
  have similar symptoms
• Smallpox
• 1 case anywhere in the world

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Conditions Under Which Epi Field Investigation
Occurs

• Situations where
• Event unexpected
• Immediate response required
• Extent of investigation limited by need for
  timely intervention
• Assess urgency of event

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Factors Affecting Urgency

• Severity of illness
• Unusualness of occurrence
• Extent of outbreak
• Numbers of persons/households/sites
• Timely intervention possible
• Institutional support
• E.g., hospital with infectious disease
  professionals involved

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Preliminary Response

• Symptom profile of initially reported person(s)
• Confirm diagnosis
• Onset dates duration of illness
• Characteristics of affected persons
• Demographics, recent travel
• Pertinent medical history
• If others similarly affected
• Confirm diagnoses!

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Elements of an Epidemiologic Field Investigation

• Determine existence of epidemic (including
  confirming diagnoses)
• Orient info by person/place/time
• Develop case definition count cases
• Develop and test hypotheses on specific exposures
  causing illness
• Identify persons at risk
• Execute control and prevention measures
• Write-up plan for further study

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Essential Tasks of Investigation

• Investigation
• Data collection analysis
• Case interviews contact tracing
• Surveillance
• Monitoring
• Active surveillance with affected institution(s)
• Evaluation of interventions
• Communications, managing personnel, etc.

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Conducting Epi Field Investigations at MCHD

• Routine activity for some programs
• Communicable Disease
• Environmental Health
• STD
• TB
• Large event requires surge capacity

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Disease and Outbreak Reporting in Oregon
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Disease Outbreak Reporting in Oregon

• Specific conditions defined by Oregon
  Administrative Rules,
• Chapter 333
• Divisions 12, 17, 18, 19, 24, 56
• Legally required reporting through physicians and
  labs
• Passive surveillance

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Reported by Physicians(Excluding STDs)

• OTHER
• Animal bites
• Any Arthropod-borne infection7
• HUS
• Lead poisoning
• Marine intoxications
• Any Outbreak of disease
• Pesticide poisoning
• Any Uncommon illness of
• potential public health
• significance
• TIMING OF REPORTS
• Immediatelyday or night
• Within 24 hours
• Within 1 working day
• Within 1 week

Malaria Measles (rubeola) Meningococcal disease
Plague Polio Rabies Rubella Pertussis Q
fever Salmonellosis (incl. typhoid) Shigellosis Ta
enia solium/Cysticercosis Tetanus Trichinosis Tube
rculosis Tularemia Vibrio infection Yersiniosis

• Anthrax
• Botulism
• Brucellosis
• Campylobacteriosis
• Cryptosporidiosis
• Cyclospora infection
• Diphtheria
• Escherichia coli (Shiga-tox.)
• Giardiasis
• Haemophilus influenzae
• Hantavirus
• Hepatitis A
• Hepatitis B
• Hepatitis C (new infections)
• Hepatitis D (delta)
• Legionellosis
• Leptospirosis
• Listeriosis
• Lyme disease

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Lab Reportable Only

• Tick-borne illnesses
• Ehrlichia
• Rickettsia
• Lab reporting often more reliable than physician
  reporting

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Response to Reports

• Report or diagnosis confirmed by local Community
  Health Nurse
• State receives notification assists as requested
  
• Follow-up locally
• Investigative Guidelines

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Investigative Guidelines

• For most reportable conditions
• Disease Reporting
• The Disease and Its Epidemiology
• Case Definitions, Diagnosis, and Laboratory
  Services
• Routine Case Investigation
• Controlling Further Spread
• Managing Special Situations

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Overview of Local, State, and Federal Roles

• LHD has public health authority in Oregon
• State
• Track data on public health conditions
  reporting federal level
• Support LHD
• Liaison with other states and federal
• Federal
• National disease reporting data
• Support state and local health departments
• Control/release certain pharmaceuticals

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State Structure
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Role of the State in an Investigation

• Receive information on reportable condition
• Timeframe set out in BT/CD Assurances
• Notification summary of findings/actions
• Support multi-county investigations
• Counties decide on lead state assists
• Support/conduct investigation if county resources
  inadequate
• Get LHD agreement
• Liaise with CDC
• Technical advise, obtain pharmaceuticals/
  vaccines, etc

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Other Aspects of Local-State Relationship

• State not a regulatory agency
• State does control funds
• In a declared emergency, State Health Officer has
  expanded powers

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Federal Structure
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Role of the CDC in an Investigation

• Support state and local public health
• Technical experts
• Laboratory testing
• Pharmaceuticals vaccines
• Lead multi-state outbreaks
• Coordinate information nationally
• Liaise with other countries international
  organizations

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Epi Activities in an ICS Context
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Possible BT Event ICS Structure (Epi Functions)
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Operations Section Epi Field Activities

• Hospital-Based Surveillance
• Active surveillance case finding
• Info on medical management
• Case Investigation
• Confirm cases assure appropriate specimens
  collected
• Detailed interviews
• Medical social history and possible contacts
• Contact Tracing
• Follow-up with contacts case finding
• Education, symptoms, prophylaxis, additional
  contacts

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Planning Section Epi Planning

• Epidemiologic information needed to direct
  operations
• Plan investigation
• Develop provide materials training
• Assure collection entry of data from Ops epi
  field activities
• Analyze and summarize epi data
• Case numbers disease rates
• Populations at risk prophylaxed

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Scenario Example
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Scenario First Report

• MCHD Communicable Disease Program receives these
  two reports
• A County jail prisoner has died 1 staff 4
  other inmates in hospital w/ similar symptoms
• Symptoms chills, high fever, body pains, chest
  discomfort, and a very bad cough
• Local hospital ICP reports 2 ED workers
  hospitalized with a serious respiratory illness

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Factors Affecting UrgencyScenario Example

• Severity 1 death 5-7 hospitalized
• Unusualness Age / time of year / possible
  number
• Extent gt1 institution
• Timely intervention possible ?
• Institutional support Good, but might involve
  multiple institutions

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Preliminary Response Scenario Example

• Symptom profiles
• Comparable symptoms among all ill onsets within
  2 days
• Initial inmate died within 3 days
• Characteristics of affected persons
• Initial inmate homeless man arrived in town
  within 2 days of arrest
• ED workers worked same shift recent death in ED
  on that shift

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Scenario Day 2

• Corrections
• Dead inmate diagnosed as pneumonic plague
  confirmation pending
• Additional ill
• 2 corrections officers 1 nurse 8 inmates
• Hospital
• Pneumonic plague diagnosed in both HCWs
• 1 HCW died Other seriously ill child of dead
  HCW symptomatic
• 20 total cases (17 from Corrections, 3 from
  hospital) with 2 deaths