Surveillance: An Overview

Surveillance: An Overview Prof Ahmed Mandil KSU College of Medicine

Headlines • Public health approach • Definitions • Components of a Surveillance System • Reporting and Feedback • Steps of Surveillance • Uses of Surveillance Data • Examples of Surveillance Activities Surveillance

Risk Factor Identification: What is the cause? Surveillance: What is the problem? Implementation: How do you do it? Public Health Approach Intervention Evaluation: What works? Problem Response Surveillance

Definitions (I) • Register: a list of persons or disease cases in a community, organization or group of people which does not have a control component (as in a surveillance system). An example is cancer registers such as the National Cancer Registry in Riyadh • Monitoring system: a general term describing a system for watching or checking on a person or thing • Surveillance of disease: continuous scrutiny of all aspects of occurrence and spread of disease that are pertinent to effective control Surveillance

Definitions (III) • Surveillance of persons: continuous scrutiny of disease contacts or high risk groups in order to promote recognition of infection or illness • Sentinel event: "a preventable disease / disability/death whose occurrence serves as a warning that prevention may need to be improved". Sentinel surveillance represents a wide range of activities that focus on key health indicators in the population. Surveillance

Surveillance: Comprehensive Definition Ongoing, systematic collection, analysis, and interpretation of data essential to planning, implementation, and evaluation of interventions, closely integrated with the timely dissemination of these data to other stake holders (e.g. health professionals, public officials, international agencies, general public) Surveillance

Components (I): Introduction A surveillance system is a monitoring process with a control system. The key words in such a system are: registration and monitoring of disease occurrence. It simulates a thermostat in a home with central heat and air-conditioning. Inhabitants of the home set the desired (comfortable) temperature on a thermostat. The thermostat 's thermometer "senses" temperature. It then compares the "actual" with "desired" temperature. It sends "control signals" to the heater or the air conditioner: if the temperature is too high, the air-conditioner goes on; conversely, if the temperature is too low, the heat goes on. Surveillance

Components (II) Similarly, the components of a surveillance are: • Sensor: identifies the state of health. Examples are: local physicians (for notifiable diseases), health workers, labs (for routine sampling, e.g. for genetic disorders), teachers & school nurses (for disease-related absenteeism), industrial physicians, or annual examination of the military • Reference Signal: the output of the sensor Surveillance

Components (III) • Monitor & Expectations: compares the reference signal with "expectations". This is usually an epidemiologist, who compares the disease occurrence with a prior expectation (threshold of concern) and responds accordingly. • Error Signal: output of the monitor which measures difference between performance (reference signal) and expectation. Example: morbidity & mortality weekly reports. • Controller: person or organization that takes corrective action aimed at reducing the error signal, i.e. initiates prevention and control activities. This might be the local health officer (regionally), or the chief medical officer (e.g. minister of health) if a national decision is needed. Surveillance

Sensor (Reporters) Reference Signal (Sensor output) Controller (Decision maker) Monitor Error Signal (Monitor output) Expectations COMPONENTS OF A SURVEILLANCE SYSTEM Surveillance

Feedback & Reporting • Passive reporting: mailing printed forms by physicians and nurses of all cases of reportable diseases observed in previous week, or telephone reporting in other cases. • Active Reporting: ministry of health contacts physicians and nurses at periodic intervals requesting data on specific diseases. (not as common as passive reporting) Surveillance

Steps for Surveillance • Defining the problem • Collecting data • Entering / processing data • Interpreting data • Reporting results • Using results to plan interventions • Evaluating the surveillance system • Updating the system Surveillance

Surveillance Sources(Communicable Diseases) • Morbidity and mortality reports; • Reports of field investigations of epidemics and individual cases • Lab isolation and identification of infectious agents • Data concerning vaccines, toxoid, immune globulins, and insecticides • Immunity levels in segments of the population. Surveillance

.Surveillance Sources(Non-Communicable Diseases) • Notifiable diseases: lead poisoning reporting systems • Vital statistics (death certificates) • Sentinel surveillance (SENSOR): for occupational risks • Disease registries: cancer, ARF/RHD registries • Health surveys: behavioral risk factor telephone surveys • Census data: poverty rates by district/region/city Surveillance

Uses of Surveillance • Estimate magnitude of the problem • Portray the natural history of a disease • Determine distribution and spread of illness • Detect outbreaks • Generate hypotheses, stimulate research • Evaluate control and prevention measures • Monitor changes in infectious agents • Detect changes in health practices • Facilitate planning Surveillance

Uses of Public Health Surveillance • Estimate magnitude of the problem • Portray the natural history of a disease • Determine distribution and spread of illness • Detect outbreaks • Generate hypotheses, stimulate research • Evaluate control measures • Monitor changes in infectious agents • Detect changes in health practices • Facilitate planning Surveillance

15 10 Reported cases per 100,000 population 5 0 1968 1973 1978 1983 1988 1993 1998 Year Shigellosis1968-1998 Source: CDC. Summary of notifiable diseases. 1998.

160 National Center for Infectious Diseases (NCID) data* National Electronic Telecommunications System for Surveillance (NETSS) data 140 TOXIC SHOCK SYNDROME (TSS) United States, 1983-1998 120 Reported cases 100 80 60 40 20 0 1992 1989 Year (Quarter) 1983 1984 1986 1987 1988 1990 1991 1993 1994 1995 1996 1997 1998 *Includes cases meeting the CDC definition for confirmed and probable cases for staphylococcalTSS. 1985 Surveillance

110 100 90 80 70 60 50 40 30 20 10 0 Botulism (Foodborne)United States, 1978-1998 Laboratory-confirmed cases* NETSS data Outbreak caused by potato salad, NM Outbreak caused by sautéed onions, IL Outbreak caused bybaked potatoes, TX Outbreak caused by fermented fish/sea products, AK Reported cases 1978 1983 1988 1993 Year 1998 Source: CDC. Summary of notifiable diseases. 1998. *Data from survey of state epidemiologists and directors of state public health laboratories. Not yet available for 1998.

Examples (I) • For diseases: • Communicable diseases: influenza, HIV/AIDS, sexually-transmitted infections • For disease outbreaks: e.g. food poisoning, salmonelosis, cholera • Non-communicable diseases: lead poisoning, cancer, hypertension, diabetes • Risk factors: tobacco use, physical exercise Surveillance

Examples (II) • For emergencies: bioterrorism, chemical, radiation, natural disasters • For hospitals: e.g. nosocomial infections. • In the industry: for occupational disorders. • In the military: for diseases of the recruits Surveillance

References • Teutsch SM, Churchill RE. Principles and practice of public health surveillance. Oxford: Oxford university press, 2000 • Surveillance of communicable disease surveillance: http://www.cdc.gov/idsr/resources.htm • Surveillance of emergencies: http://emergency.cdc.gov/episurv/ • Surveillance of non-communicable disease risk factors: http://www.who.int/mediacentre/factsheets/fs273/en/ Surveillance

Surveillance: An Overview