Introduction to Surveillance Session 4, Part 1

Learning Objectives Session 4, Part 1 Explain the surveillance “feedback loop” of data and information flow through local, state, and federal channels Describe characteristics of three different methods of surveillance: active, passive, and syndromic List 5 applications of public health surveillance

Overview Session 4, Part 1 How surveillance works Passive, active, and syndromic surveillance Applications of surveillance data Surveillance limitations and challenges

How Surveillance Works

What is Surveillance? The ongoing systematic collection, analysis, and interpretation of health data, essential to the planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination to those who need to know. - Centers for Disease Control and Prevention (CDC)

Physicians Laboratories STD clinics Community health clinics Emergency departments (EDs) Physicians Laboratories STD clinics Community health clinics Emergency departments (EDs) County and state health departments, CDC analyze data using statistical methods Standardized data collection Surveillance Flow

Physicians Laboratories STD clinics Community health clinics EDs Physicians Laboratories STD clinics Community health clinics EDs County and state health departments, CDC analyze data using statistical methods Public health officials Health directors Health policy officials Public health officials Health directors Health policy officials Standardized data collection Dissemination to those who need to know Surveillance Flow

Physicians Laboratories STD clinics Community health clinics EDs Physicians Laboratories STD clinics Community health clinics EDs County and state health departments, CDC analyze data using statistical methods Public health officials Health directors Health policy officials Public health officials Health directors Health policy officials Standardized data collection Dissemination to those who need to know Change in public health practice (vaccination, reduction of risk factors, medical intervention, etc.) Public health planning and intervention Surveillance Flow

Physicians Laboratories STD clinics Community health clinics EDs Physicians Laboratories STD clinics Community health clinics EDs County and state health departments, CDC analyze data using statistical methods Public health officials Health directors Health policy officials Public health officials Health directors Health policy officials Standardized data collection Dissemination to those who need to know Change in public health practice (vaccination, reduction of risk factors, medical intervention, etc.) Public health planning and intervention Public health evaluation Surveillance Flow

National Notifiable Diseases Surveillance System (NNDSS) National list –~60 nationally infectious diseases –~6 non-infectious diseases / conditions –Produced by CSTE each year State list –Each state modifies as needed –State law mandates reporting requirements

Sources of Surveillance Data Mortality reporting –Legally required as part of vital statistics programs in most countries Morbidity reporting –Notifiable disease reporting (legally required) or specially created systems

Sources of Surveillance Data Surveys, e.g. BRFSS Epidemic reporting / cluster investigation Laboratory investigations and reporting Individual investigations

Management of Surveillance Data Timeliness Completeness Accuracy Analysis of Surveillance Data Trends Clusters Patterns

Methods of Surveillance Passive Active Syndromic

Passive Surveillance 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.

Communicable Disease Reporting: Passive Surveillance Hospital PhysicianLab Local Health Department State CDC Public

Excerpt: 2011 Recommended Reportable Diseases Anthrax Arboviral neuroinvasive and non-neuroinvasive diseasesArboviral neuroinvasive and non-neuroinvasive diseases –California serogroup virus disease –Eastern equine encephalitis virus disease –Powassan virus disease –St. Louis encephalitis virus disease –West Nile virus disease –Western equine encephalitis virus disease Babesiosis Botulism –Botulism, foodborne –Botulism, infant –Botulism, other (wound & unspecified) Brucellosis Chancroid Chlamydia trachomatis infectionChlamydia trachomatis infection Cholera Specific reportable diseases and conditions are mandated by state law, and can differ for every state.

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

Communicable Disease Reporting: Active Surveillance Hospital PhysicianLab Local Heath Department State CDC

Outbreak investigations Other times when complete case ascertainment is desired –Research study –Incomplete information reported Active Surveillance Applications

Advantages and Limitations Passive Surveillance Advantages –Inexpensive –Low data collection burden for health department Limitations –Under-reporting –Missing information –Can be slow Active Surveillance Advantages –Complete data –Flexible Limitations –Costly

Syndromic Surveillance The 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.

What are “Indicators of Disease?” Clinical signs that we can categorize into syndromes Not a specific diagnosis Example: Cough + Sore throat + Fatigue + Fever = Influenza-like illness

Syndromic Surveillance Example Source: Daily temperatures and GP visits for heat syndrome, Bordeaux, 1 June – 31 Aug, 2006

Common Syndromes Under Surveillance Gastroenteritis Influenza-like illness (ILI) Meningitis / Encephalitis Rash / Fever sydromes Botulinic syndrome Hemorrhagic syndromes

Why Do Syndromic Surveillance? Early detection –Ideally automated Outbreak characterization –Magnitude, rate of spread, effectiveness of control measures Detection of unexplained deaths

Limitations of Syndromic Surveillance (1) Limited by available data –False alarms –Inconsistent reporting sources –IT failure

Limitations of Syndromic Surveillance (2) Inadequate sensitivity: failure to detect outbreaks or emergencies –Outbreak is too small –Population disperses after exposure, cluster not evident

Limitations of Syndromic Surveillance (3) Costly –Infrastructure and staff –Complicated data use agreements

Surveillance Applications

Applications Establish public health priorities Aid in determining resource allocation Assess public health programs –Facilitate research Determine baseline level of disease Detect epidemics –Estimate magnitude of the problem –Determine geographical distribution

Establish Public Health Priorities Frequency –Incidence, prevalence, mortality, years of life lost Severity –Case fatality rate, hospitalization, disability Cost –Direct, indirect

Resource Allocation TUBERCULOSIS: Reported cases per 100,000 population, United States, 2010 Source: National TB Surveillance System MMWR March 25, 2011 / 60(11);

Assess Public Health Programs Laboratory Confirmed Cases of Meningitis C, England and Wales, Source: Health Protection Agency, Infectious Diseases, Meningitis, Epidemiologic Data

Determine Baseline Rates TB Case Rates in U.S.-born vs. Foreign-born Persons United States, 1993–2009* Cases per 100,000 *Updated as of July 1, 2010.

Early Detection of Epidemics Boston, MA

Surveillance Limitations and Challenges

Surveillance Limitations (1) Uneven application of information technology –Paper-based versus electronic Timeliness –Reporting time requirement –Reporting burden

Surveillance Limitations (2) Completeness –Unreported cases –Incomplete reports –Consistency of reporting

CDC Varied communications methods and security - specific to each system- including paper forms, diskettes, , direct modem lines, etc. Current Situation MMWR Weekly Tables MMWR Annual Summaries Program Specific Reports and Summaries State Health Dept TIMSSTD*MI S HARS STD*MISTIMSNETSS EIP Systems NETSS STD*MIS (Optional at the Clinic) TIMS (Optional at the Clinic) PHLISEIP Systems * PHLIS HARS STD* MIS TIMSNNDSSEIP Systems PHLIS * EIP Systems (ABC, UD, Foodnet) Data Sources Physicians Varied communications methods and security - specific to each system - including diskettes, , direct modem lines, etc. Chart Review Lab Reports Reporting by Paper Form, Telephone & Fax Statistical Surveys for Chronic Diseases, Injuries and Other Public Health Problems City/County Health Department Limitations: Multiple Categorical Systems

National Electronic Disease Surveillance System (NEDSS) Not a traditional surveillance system Electronically integrates existing surveillance systems for easy data collection, storage and access Includes security measures to ensure confidentiality Allows data queries

Surveillance Challenges Assessing quality of the data Using case definitions Translating data into information

Quality of the Data Completeness of case ascertainment Assessment of completeness, accuracy, and timeliness of reports ‘Tip of the iceberg’

Surveillance Challenges by Definition Clinical vs. surveillance case definitions Cases ‘worked’ vs. cases ‘counted’ Place of exposure, residence, or diagnosis Re-infection or duplicate report Frequencies by date of onset, date of diagnosis, or date of report

Translating Data into Information Provides the basis for public health action Requires sound analysis and interpretation Extracts meaningful, actionable findings Requires clear presentation of complex issues

Summary Public health surveillance is the ongoing collection, analysis, interpretation of health data and dissemination of information Surveillance data are used for planning, implementation, and evaluation of public health practice Surveillance data collection can be passive, active, or syndromic; each type presents unique advantages and limitations

References and Resources Bonetti M, et al. Syndromic Surveillance. Harvard Center for Public Health Preparedness; August Public Health Surveillance Program Office [Web page]. Centers for Disease Control and Prevention. Available at: Accessed March 1, State Electronic Disease Surveillance Systems --- United States, 2007 and MMWR Morb Mortal Wkly Rep. 2011;60(41): Available at: 41a3_w. Accessed March 1, a3_w Nationally Notifiable Conditions [Web page]. Division of Notifiable Diseases and Healthcare Information, Centers for Disease Control and Prevention. Available at: Accessed March 1,

References and Resources Notifiable Diseases/Deaths in Selected Cities Weekly Information. MMWR Morb Mortal Wkly Rep. 2004;53(21): Available at: Accessed March 1, Flamand C, Larrieu S, Couvy F, Jouves B, Josseran L, Filleul L. Validation of a Syndromic Surveillance System using General Practioner House Calls Network, Bordeaux, France. Eurosurveillance. 2008;13(25). Available at: Accessed March 1,