Epidemiological surveillance

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Epidemiological surveillance is the continued watchfulness over the distribution and trends of incidence through the systematic collection, consolidation and evaluation of morbidity and mortality reports and other relevant data, and the regular dissemination of data to all who need to know. As such, it is a key element in epidemiology.

This term may be used in two ways. In broader sense, surveillance has been equated with the routine health information system which gives idea about the total health situation. in narrower sense, it is used to refer to specific information system pertaining to specific disease or any other health related event.


1. assessing magnitude of problem

2. monitoring implementation of health programs

3. understanding local epidemiology of the problem

4. assessing changes in trend of disease or its distribution

5. identifying specific groups at risk

6. to enable predictions about pattern of occurrence of diseases

7. in assessing the impact of the programme intervention for control of diseases


Passive surveillance: It is the routine reporting of the cases of diseases reaching health care facilities for treatment or service.No special effort is made to find unsuspected disease incidents. Passive surveillance will usually only detect disease in those who get sick, meaning that healthy carriers and long incubation periods combined with passive surveillance can maintain a reservoir of undiscovered disease carrying agents.

Active surveillance: A search is conducted to find cases in the community mainly through door-to-door surveys. This method includes the gathering of information from institutions and healthcare providers.

Sentinel surveillance: It is a reporting system based on selected institutions or people who provide regular, complete reports on one or more diseases occurring ideally in a defined attachment. It also provides additional data on cases.

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