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Table 2 Key definitions of some common terms

From: Surveillance-response systems: the key to elimination of tropical diseases

Term Definition
Classical definition of surveillance Ongoing systematic collection, analysis and interpretation of data, usually incidence of cases of disease. In the WHO Global Malaria Action Plan (GMAP), surveillance is defined as follows: “.... is aimed at discovery, investigation, and elimination of continuing transmission, the prevention and cure of infection and final substantiation of claimed eradication.”
Surveillance and response or surveillance as an intervention Aiming to reduce transmission through monitoring and evaluation (M&E), this activity requires a shift from measuring morbidity and mortality to detecting infections and measuring transmission using novel, field-ready tools and strategies for the active detection of asymptomatic infection. It may include DNA-based and/or serological biomarkers, new effective approaches tracking population dynamics, effective field-based mapping linked to databases, improved measurements of mapping transmission and improve the feasibility, efficiency and cost-effectiveness of new health information systems.
Active surveillance A structure engaging health professional to frequently monitor health care providers or the population to gather information about health situations. Although not cost-effective, active surveillance provides the most accurate and timely information.
Passive surveillance A structure by which a health authority takes delivery of reports submitted from district to provincial hospitals, clinics, public health units or other sources. It is a cost-effective approach covering most populations, and offering critical information for monitoring a community’s health. However, due to its dependency on data provision from different institutions or hospitals, the quality of data can be hard to assess.
Sentinel surveillance A structure supported by a reporting system based on selected institutions or individuals that provide regular, complete reports on one or more diseases occurring ideally in a defined catchment. It also provides additional data on individual cases.
Integrated surveillance A combination of active and passive systems using a single organisation that collects information about multiple diseases or behaviours of interest to several intervention programmes (e.g. health facility-based system may continuously gather data that are linked to disease-specific data and quality control of the information or on multiple infectious diseases and disorders.
Syndrome surveillance An active or passive system that uses case definitions that are based entirely on clinical features without any clinical or laboratory diagnosis. It is inexpensive and is faster than systems that require laboratory confirmation mostly applied in developing countries but lack of specificity (subjective) and require further analysis.
Control The reduction of disease incidence, prevalence, morbidity or mortality to a locally acceptable level as a result of deliberate efforts.
Elimination The reduction to zero of the incidence of infection in a defined geographical area as a result of deliberate efforts and continued measures to prevent re-establishment of transmission are required.
Eradication The permanent reduction to zero of the worldwide incidence of infection, as a result of time-bound, deliberate efforts. Once eradication has been achieved, intervention measures are no longer needed.