Introduction to Public Health Surveillance

July 26, 2010

Public Health SurveillanceOngoing, systematic collection, analysis, and

interpretation of health-related data essential to the planning, implementation,

and evaluation of public health practice, closely integrated with the timely

dissemination of these data to those responsible for prevention and control.

Centers for Disease Control and Prevention (CDC)

Surveillance as a Tool for Community ProtectionInitially used for disease controlNow used for:

Communicable and infectious diseaseChronic diseaseInjuryOccupational hazardsOther conditions and behaviors

Objectives of Public Health SurveillanceEstimate magnitude of the problemDocument distribution and spread of health eventUnderstand the natural history of a diseaseDetect outbreaks or epidemicsTest hypotheses about origin of diseaseEvaluate control strategiesMonitor changes in infectious agentsMonitor isolation activitiesDetect changes in health practiceAssess the quality of health careAssess safety of drugs and proceduresIdentify research needs and facilitate researchFacilitate planning

Principles and Practice of Public Health Surveillance, Teutsch, SM, Churchill, RE. 2000 Oxford University Press.

ObesityUnited States, 1987-1998

Types of SurveillancePassiveActiveSyndromic

Passive SurveillanceProvider initiated

Laboratories, physicians, or other health care providers regularly report cases of disease to the local or state health department based on a standard case definition of that particular disease.

Active SurveillanceHealth agency initiated

Local or state health departments initiate the collection of specific cases of disease from laboratories, physicians, or other health care providers.

Outbreak investigationsContact hospitals and practitionersUse media to locate cases

Other times when complete case ascertainment is desired (e.g., research study)

Active Surveillance Applications

Syndromic SurveillanceThe ongoing, systematic collection, analysis, interpretation, and application of real-time indicators for disease that allow for detection before public health authorities would otherwise identify them.

IndicatorsClinical signs

categorized into syndromes

Not a specific diagnosis

Example: Cough + Sore throat + Fatigue + Fever =

Influenza-Like Illness (ILI)

Purposes of surveillance at state and local level1. Trigger disease control activities

a) Accurate diagnosis and treatment b) Management of persons exposed to diseasec) Identify disease outbreaksd) Recognize an unusual event

2. Plan, implement, and evaluate health promotion and disease prevention programs

Notifiable Disease Surveillance SystemDepartment of Health Services (DHS), Division of

Public Health (DPH)Wisconsin Electronic Disease Surveillance System

(WEDSS) facilitates reporting, investigation, and surveillance

Report de-identified, case-level data to Centers for Disease Control and Prevention (CDC) weekly

National Notifiable Disease Surveillance System (NNDSS), CDC60 nationally notifiable infectious diseasesList developed and revised by Council of State and

Territorial Epidemiologists (CSTE) and CDCCDC publishes national data in MMWR (Morbidity &

Mortality Weekly Report)

Legal authority for disease surveillance

Chapter 252 Communicable diseases

Defines powers and duties of Department of Health Services and local health officers

Requires reporting of communicable disease cases and authorizes isolation and quarantine

Authorizes communicable disease prevention and control programs

Communicable Disease Reporting

Who Needs to Report?

Licensed healthcare personnel

Labs

Health care facilities

Teachers, principals, or nurses in a school or day care center

Any person who knows or suspects a person has a communicable disease

Category I Reportable DiseasesUrgent public health importanceReported immediately by phone, followed

by entering into WEDSS (or 4151)Includes vaccine preventable diseases,

bioterrorism agents, food & waterborne outbreaks

Prompt public health intervention directed at limiting spread in community

Category II Reportable DiseasesLess urgent public health importance

Most reportable diseases fall in this category

Reported via WEDSS (or on 4151 or 4243 for STDs) by mail or other means within 72 hours of identification

Public health intervention varies depending on disease

Category III Reportable DiseasesHIV and AIDS

Reported directly to state epidemiologist

State distributes to appropriate local health department for follow up

Communicable Disease Reporting ResourcesEpiNet manualDPH Communicable Disease

website including:Disease Fact SheetsInfo for healthcare providers

WEDSS (Wisconsin Electronic Disease Surveillance System)

Communicable disease phone contacts

AVR (Analysis, Visualization, & Reporting)

Control of Communicable Diseases Manual

Outbreak and unusual event detectionCommunicable disease

reportingSchool, daycare, and worksite

absenteeism surveillanceLocal surveillance groups and

systemsSentinel surveillanceSpecial event surveillanceAlerting systemsOther syndromic surveillance

systems

Sentinel Surveillance for ILIWisconsin Sentinel

Clinician Program at DPH

Clinical surveillance for influenza

Clinicians report total # of patients and # who meet ILI case definition fever > 100 degrees

with cough or sore throat

Disease surveillance: Sentinel Chickens

Serology testing Sentinel flock

Alerting SystemsLocal contact lists

Performance measure #6 Local health department can assure 70% of local response partners receive public health emergency communication messages

Send Word NowAlerting services

Epi-XCIDRAP

Wisconsin Health Information Exchange (WHIE)Automated, real-time data on ED (emergency

department) visits with chief complaint of:‘fever-flu’ (e.g. ILI)GIrespiratory (e.g. shortness of brief, wheezing

etc that don’t fit chief complaint of fever-flu)‘other’ chief complaints (‘other’ = those that

don’t fit in the other categories). 

WI-TRAC (Wisconsin Tracking, Resources, Alerts and Communication)Wisconsin Hospital Emergency Preparedness

Program systemHospital alerting and communication toolAvailable to EMS, First Responders, public

health, physician offices, law enforcement, fire departments, Dispatch Centers, and Emergency Management directors

Deb Van Matre, WI Trac State System Administrator, at dvanmatr@fmlh.edu

Outbreak and Unusual Events ResourcesCommunicable disease resources (WEDSS

outbreak tab) Food and Water Borne Disease Outbreak

Investigation manualWisconsin Hazardous Substances Emergency

Events Surveillance (HSEES), DHSEmergency Preparedness and Response

Surveillance, CDCPHEP (Public Health Emergency Program)

plan

Monitor health status & disease trendsDisease outcomesDeterminants and risk factors for

communicable and non-communicable diseaseExamples:

Vaccine coverageVaccine-preventable disease morbidityScreening rates (mammography, cholesterol)Smoking prevalenceSmoking-related morbidity and mortality

Chapter 255 – Chronic Disease, Injuries, MCHCancer registry - requires hospitals, physicians,

and labs to report cancer or precancerous conditions

Injury prevention - requires DHS to:Maintain an injury prevention program that includes

data collection, surveillance, education, and the promotion of intervention

Assist local health departments and community agencies in local program development and evaluation

MCH: Identifies responsibilities for infant blindness;

newborn hearing screening; birth defect prevention and surveillance

Identifies responsibilities related to sudden infant death syndrome and shaken baby syndrome and impacted babies.

Resources for Monitoring Disease TrendsVital recordsDisease registriesSurveysAdministrative

dataOther data sources

Criteria for choosing priorities for surveillanceFrequency of event (incidence, prevalence,

mortality)Severity (fatality rate, hospitalization rate,

disability rate, years of potential life lost, quality adjusted life-years lost)

Cost (direct and indirect)PreventabilityCommunicabilityPublic interest

Principles and Practice of Public Health Surveillance, Teutsch, SM, Churchill, RE. 2000 Oxford University Press.

Steps in planning a Surveillance System1. Establish objectives2. Develop case definitions3. Determine data source or data-collection

method4. Develop data collection instrument (if nec)5. Field-test methods (if nec)6. Develop analysis approach7. Decide how you will disseminate results8. Ensure use of analysis and interpretation

Principles and Practice of Public Health Surveillance, Teutsch, SM, Churchill, RE. 2000 Oxford University Press.

Steps in evaluating a surveillance system

Clearly define the purpose and objective of the system

Describe the operation of the systemDocument how the system has been usefulAssess attributes of the system (timely,

flexible, representative, cost-effective, complete, simple/easy to apply, acceptable to users, sensitive, specific)

Estimate the cost (direct and indirect)

School Surveillance Evaluation Example

Purpose: increases the ability to detect outbreaks in a timely way and enhance understanding of communicable diseases circulating among school-aged children.

Operation: how system was carried out by LPHA and schools (what data is collected, when, how, and by whom); thresholds

Documentation of usefulness: Survey results from schools and LPHAs, data/charts, increased communication between school and LPHA

Assessment of attributes: Was data timely and complete?

Costs: Time of LPHA, school, consortium epidemiologists