Table of Contents
Introduction:
- According the Centers for Disease Control and Prevention (CDC), epidemiological surveillance is “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 of these data to those who need to know.”
- Surveillance in general means to watch over carefully or to observe any event. For general example use of CCTV is also a kind of a surveillance.
- Surveillance in public health is the continuous, watching of the incidence and distribution of health-related events through systematic collection, analysis and interpretation of data needed for the planning, implementation, and evaluation of public health practice.
- It can be carried out to monitor changes in disease frequency or to monitor changes in the levels of risk factors.
- Surveillance is systematic and ongoing process
Characteristics of Ideal Surveillance:
An ideal surveillance should be:
- Simple
- Timely
- Representative
- Flexible
- Sensitive
- Strong predictive value
- Acceptable to
- The public
- Health care providers
- Cost-effective
Importance of surveillance:
- To assess the health status
- All the data collected are the reflection of health of people
- Keeps the record of existing health problems
- Helps in the interpretation of mortality and morbidity status
- To detect the change in the disease trend and health practices
- Continue recording of data notifies about the disease trend
- Keeps the track of disease
- Surveillance is also helpful for finding the natural history of disease.
- Collection of data for Planning, Monitoring and Evaluation
- The data required for PME is provided by surveillance
- It is the base for evidence-based policy formation
- Helps the program developer in priority setting
- Also helps in assessing the effectiveness of the interventions
- Early warning and detection of outbreaks
- Surveillance notifies about the disease
- All the data too helps in detecting the outbreaks
- Hence helps in preparedness
- To estimate the size of a health problem
- To detect epidemics or define a problem
- To facilitate emergency planning
Types of Surveillance:
-
Active Surveillance
- Refers to active finding of the cases.
- Designated staffs review the records physically, visits the health facility, and confirms with the health practitioner to find the particular cases.
- Often used for the disease which is at the verge of elimination and eradication and also in the time of outbreak investigation.
- Requires more resources
- Active Surveillance can be also used to check the validity of passive surveillance
- Reporting is usually more accurate here as it is performed by those specially assigned to conduct this activity
-
Passive Surveillance
- Surveillance in which the available data on diseases or conditions are used
- It refers to regular monitoring or reporting of the cases without active involvement in identification/reporting by the health personnel
- Simple and very easy to carry out
- All institutions that provide health services to general people are the part of this surveillance.
- They forward their records to the designated departments where all the reports are compiled
- Uniform format of reporting is followed
- Health management information system of government is an example of passive surveillance
- Inconsistency of recording can cause problem as things may not be taken seriously all the time
3. Sentinel Surveillance
- It is a surveillance system which is used when the need of high quality data cannot be met through passive surveillance
- It is a system where specific catchment area is selected for surveillance.
- Selection of sentinel surveillance site depends on possibility of high probability of cases/disease
- It deliberately involves limited network of carefully selected reporting sites. Example: a network of large hospitals might be used to collect high-quality data on various diseases
- Sites are selected on the basis of population flow, previous outbreak of disease, high presence of risk group, etc.
- Sentinel Surveillance is not suitable for detecting rare disease
Steps of surveillance:
Reporting:
- Data has to be reported by the health worker, staffs , etc
- Data needs to be reported in pre-specified format
Accumulation
- The reported data needs to be collected and compiled
- The data are collected in a designated departments
- Data collection follows the certain chain
Data Analysis
- All the collected are then analyzed
- The data are converted in terms of rates, ratios, proportion, figures etc
Interpretation and action
- Surveillance doesn’t stops in data collection
- Wise judgement needs to be made
- The information needs to be disseminated so that the further action are taken
Limitations of Surveillance:
- Surveillance depends upon the reporting so underreporting could be a problem.
- Inconsistency in reporting
- Reporting may not be representative
- Takes time for data collection, analysis and interpretation
- Surveillance is on the tool of epidemiology it is not the solution to health problem.
References and for more information:
http://www.who.int/topics/public_health_surveillance/en/
http://www.ph.ucla.edu/epi/faculty/detels/PH150/Detels_Surveillance.pdf
http://www.who.int/immunization/monitoring_surveillance/burden/vpd/surveillance_type/passive/en/
https://cursos.campusvirtualsp.org/mod/tab/view.php?id=23161
https://www.gov.uk/government/publications/public-health-england-approach-to-surveillance/public-health-england-approach-to-surveillance
https://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson5/appendixe.html
http://www.uniteforsight.org/surveillance/module1
http://conflict.lshtm.ac.uk/page_70.htm
http://www.who.int/ncd_surveillance/en/steps_framework_dec03.pdf
https://www.jhsph.edu/research/centers-and-institutes/center-for-excellence-in-environmental-health-tracking/Module_3.pdf
