Public Health Surveillance Ashry Gad Mohamed MB.ChB, MPH, DrPH Prof. of Epidemiology

Contents Definition Importance Elements Objectives Types Procedures of data collection Analysis Action Reports

Public Health Surveillance “Ongoing systematic collection, analysis, and interpretation of outcome-specific data for use in the planning, implementation, and evaluation of public health practice.” CDC

Surveillance System  Data Collection  Analysis  Dissemination

Surveillance for communicable diseases remains important… The world population is highly mobile International travel and troop movements increase the risk of communicable disease transmission Migration for war and famine, and voluntary immigration increase communicable disease risk Naturally occurring disease is not our only threat

Elements of surveillance Cases and deaths due to a given disease. Laboratory results. Prevention and control measures. Environment. Vector. Reservoir. Population

Public Health Surveillance Conceptual Taxonomy Public Health Surveillance Medical Utilization and Adverse Events Disease Drug Vaccine Other Products/Services Traditional ‘Syndromic’ Infectious Disease Other Birth defect Injuries Etc.

Objectives of surveillance Identify diseases of public health importance. Identify quickly any outbreak, epidemic or unusual event. Identify risk factors. Identify high risk population. Monitor disease trend. Access current disease control activities.

What data do we collect? Should be preceeded by careful selection of diseases or conditions. Should be indicated. Specify the indicator for each item wanted to be monitored. It may requires In-Depth interview, if decision to investigate causes is taken.

Types of Surveillance Passive Inexpensive, provider-initiated Good for monitoring large numbers of typical health events Under-reporting is a problem Active More expensive, Health Department-initiated Good for detecting small numbers of unusual health events Enhanced Rapid reporting and communication between surveillance agencies and stakeholders Best for detecting outbreaks and potentially severe public health problems

Data collection Routine reporting system Advantages: Hospitals, health centers, health facilities, CHW. Advantages: Inexpensive efficient. Standardized., Disadvantages: Incomplete Busy doctors & nurses

New and complex disease entities must also be monitored… New syndromes may emerge that present in an atypical manner Syndromic surveillance uses health-related data that precede diagnosis and signal a sufficient probability of a case or an outbreak to warrant further public health response

Example of Passive Surveillance Day 1- feels fine Day 2- headaches, fever - buys Tylenol Day 3- develops cough - calls nurse hotline Day 4- Sees private doctor – dx with “flu” Day 5- Worsens - calls ambulance seen in ED Day 6- Admitted - “pneumonia” Day 7- Critically ill - ICU Day 8- Expires - “respiratory failure” Case enters surveillance system through an EDC

Example of Syndromic Surveillance Day 1- feels fine Day 2- headaches, fever - buys Tylenol Day 3- develops cough - calls nurse hotline Day 4- Sees private doctor - dx “flu” Day 5- Worsens - calls ambulance - seen in ED Day 6- Admitted - “pneumonia” Day 7- Critically ill - ICU Day 8- Expires - “respiratory failure” Case is under immediate investigation by the LHD because of the pre-diagnostic information gathered Pharmaceutical Sales Nurse’s Hotline Managed Care Org Absenteeism records Ambulance Dispatch (EMS) ED Logs

2-Sentnel reporting system Selected health units Advantages: More consistent pictures. Motivated. Disadvantages: Not representative Changed with surved population

3-Surveys and special studies Broad estimate. Measure reliability. Relieve health care workers. Disadvantages: Large sample size. Expensive

4-Case and outbreak investigations On occasion. Used as a next step

Data collection procedures Operational definition Instruments Registers Questionnaires Case investigation form Pre-test the instrument

Data collection Training Supervision Quality control Reporting

Analyze the data Summary tables. Disease charts. Maps. Rates & ratios More analysis for pattern and causes

Investigate causation Case and outbreak investigations. Verbal autopsy.

Develop an action plan What? Who? When? Where? How? Outline resources.

Prepare and present reports Review objectives. Review tables, graphs & maps. Add short narrative to explain findings. Describe action plan. Disseminate the report