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Introduction to Surveillance
Imran Ahmed Abdulkadir BSPH, MSc. PTH April. 2023
Objectives of the lecture
- (^) By the end of this lecture students will be able
to:
- (^) Define Surveillance
- (^) Identify Components of a Surveillance
System
- (^) Identify objectives and Uses of Surveillance
- (^) List Steps of Surveillance
Surveillance
- (^) Surveillance programmes can assume any character and dimension thus we have epidemiological surveillance, demographic surveillance, nutritional surveillance, etc.
Surveillance is Information for action
The main objectives of surveillance
- (^) To provide information about new and changing trends in the health status of a population, e.g., morbidity, mortality, nutritional status or other indicators and environmental hazards, health practices and other factors that may affect health.
- (^) To provide feed-back which may be expected to modify the policy and the system itself and lead to redefinition of objectives, and
- (^) Provide timely warning of public health disasters so that interventions can be mobilized.
Types of surveillance
- (^) The two common types of surveillance are passive and active surveillance.
- (^) Passive surveillance
- (^) Passive surveillance may be defined as a mechanism for routine surveillance based on passive case detection and on the routine recording and reporting system.
- (^) The information provider comes to the health institutions for help, be it medical or other preventive and promotive health services.
- (^) It involves collection of data as part of routine provision of health services.
Passive surveillance
- (^) Advantages of passive surveillance
- (^) Covers a wide range of problems
- (^) Simple and inexpensive
- (^) Covers a wider area
- (^) The disadvantages of passive surveillance
- (^) It lacks representativeness of the whole population since passive surveillance is mainly based on health institution reports.
Active surveillance
- (^) The advantages of active surveillance
- (^) The collected data is complete and accurate
- (^) The disadvantages of active surveillance
- (^) It requires good organization,
- (^) It is expensive
- (^) It requires skilled human power
- (^) It is for short period of time(not a continuous process)
- (^) It is directed towards specific disease conditions.
Conditions in which active surveillance is appropriate
- (^) There are certain conditions where active
surveillance is appropriate. These conditions are:
- (^) For periodic evaluation of an ongoing program
- (^) For programs with limited time of operation
such as elimination or eradication program.
Syndromic Surveillance
- (^) Focuses on one or more symptoms rather
than a physician-diagnosed or laboratory-
confirmed disease.
Nationally Notifiable Disease
Surveillance System (NNDSS)
- (^) Many diseases on a state list are also
nationally notifiable.
Data Sources for Public Health Surveillance
- (^) Reported diseases or syndromes
- (^) Electronic health records (e.g., hospital discharge data)
- (^) Vital records (e.g., birth and death certificates)
- (^) Surveys (e.g., National Health and Nutrition Examination Survey [NHANES])
- (^) Census data
Disease in the populaiton Level of disease
- (^) Endemic : (En=in; demos=people). It refers to the constant presence of a disease or infectious agent within a given geographic area or population group; may also refer to the "usual" or expected frequency of the disease within such area or population group. (Malaria, Diarrhoeal diseases)
- (^) Hyperendemic refers to persistent, high levels of disease occurrence.
Sporadic
- (^) The word sporadic means scattered about.
- (^) The cases occur irregularly, haphazardly from time to time, and generally infrequently.
- (^) The cases are so few and separated widely in space and time that they show little or no connection with each other, nor a recognizable common source of infection, e.g., polio, tetanus, meningococcal meningitis, dengue fever and Chikungunya.
- (^) A sporadic disease may be the starting point of an epidemic when conditions are favourable for its spread.
- (^) Many zoonotic diseases are characterised by sporadic transmission to man.
Pandemic
- (^) An epidemic usually affecting a large proportion of
the population, occurring over a wide geographic
area such as a section of a nation, the entire nation,
a continent or the world e.g., Coronavirus disease
(COVID-19) in 2020.
- (^) Pandemic also refers to an epidemic that has spread
over several countries or continents, usually affecting
a large number of people.
- (^) A worldwide epidemic.