Glossary

This glossary is a concise guide to the terminology and definitions related to animal health surveillance, aiming to facilitate communication between those commissioning, designing, implementing and contributing to surveillance activities to provide a common understanding of these different surveillance activities. The glossary includes established definitions that have been published elsewhere as well as suggestions for additional terms or refinements where gaps or difficulties in understanding were identified by the RISKSUR consortium. Unless noted otherwise, all definitions are derived from the ICAHS Animal Health Surveillance Terminology Final Report (version 1.2).
If you have additional terms to add or propose a revision to one of the definitions listed, please email us. Your suggestions will be incorporated into the glossary following a peer-review. Final recommendations regarding surveillance terminology will be made available online at the end of the project. We welcome your input!

 

A

Acceptability and engagement

Willingness of persons and organisations to participate in the surveillance system, and the degree to which each of these users is involved in the surveillance process including the participation of stakeholders in the steering and technical committees. Could include an assessment of stakeholder awareness of the system and their understanding of it. Could also assess their beliefs about the benefits or adverse consequences of their participation in the system including the provision of compensation for the consequence of disease detection.

Active surveillance

also: Proactive surveillance

Investigator-initiated collection of animal health related data using a defined protocol to perform actions that are scheduled in advance. Decisions about whether information is collected, and what information should be collected from which animals is made by the investigator.

Assessment

The assessment of a surveillance system/component is the collection and analysis of data on the relevant surveillance attributes and/or criteria. It is a technical step within the evaluation process.

Associated legislation and regulations

A description of any legislation or regulations which act as the basis for determining the requirement for surveillance including whether there are any compensation arrangements and any requirement for ethical approval.

B

Benefit

Direct and indirect advantages produced by the surveillance system. This does not need to be limited to financial savings and better use of resources but can also include any losses avoided due to the existence of the system and the information it provides. These avoided losses may include improved animal production; maintenance of a structured network of actors able to react appropriately against a future threat; improved public health; increased understanding about a disease; maintained or increased trade; or improved ability to react in case of an outbreak of disease.

Bias

The extent to which a prevalence estimate produced by the surveillance system deviates from the value of the true prevalence . Bias is reduced as representativeness is increased.

C

Case definition
  • Clinical signs or syndrome (including death)
  • Indirect indicators (e.g. drug sales, production or performance information, abattoir sub missions)
  • Gross pathology
  • Laboratory test for pathogens or toxins
  • Laboratory test for host response (e.g. serology)
  • Specified diagnostic criteria (e.g. diagnostic codes (Veterinary Investigation Diagnosis and Analysis( VIDA )) code used in GB early warning s urveillance system)
  • Risk factor(s)
Communication and dissemination

An assessment of the methods used and ease of information exchange between people involved at all levels of the surveillance system (providers, analysers and users of surveillance data). Include an assessment of the data and information provided and of the timeliness and types of outputs produced. The efforts made to disseminate these outputs including the use of web-based systems should also be assessed. The methods used to provide feedback to data providers and to increase their awareness about hazards and surveillance activities should also be assessed. Internal communication and dissemination is directed at those working within the surveillance network or system. External communication and dissemination is directed at those outside the surveillance network or system (e.g. international organisations).

Cost

The evaluation should list and quantify each of the resources required to operate the surveillance system and identify who provides eachresource. These resources could include: time, personnel, financial input and equipment.

Coverage

The proportion of the population of interest (target population) that is included in the surveillance activity.

D

Data analysis

Whether appropriate methods are used for the analysis and interpretation of data at an appropriate frequency.

Data analysis method

A description of the measures used to assess disease occurrence (e.g. incidence, prevalence, case numbers) and how the data are analysed include; the spatial and temporal methods used, the frequency of analysis, whether real-time and whether contextual information (e.g. the risk of introduction and the prior likelihood of disease) will be incorporated.

Data collection

The use of appropriate data sources and collection methods including automation of data collection where appropriate and the existence of a case definition and a data collection protocol.

Data completeness and correctness

The proportion of data that were intended to be collected that actually was collected and the proportion of data entries that correctly reflect the true value of the data collected.

Data management methods

A description of how data is managed e.g. whether a central relational database is used and the methods used to ensure confidentiality and security of information.

Data storage and management

Appropriate use and documentation of data management systems for processing information, including data processing protocols, and effective use of data verification procedures and of data storage and back-up procedures.

Design prevalence

A standard hypothetical prevalence of disease specified at the herd (herd design prevalence, P*H) or at the animal level (P*A) against which to measure surveillance sensitivity.

Source: Cameron, 2012: PVM 2015, p. 280-286

The definition is based on the concept that if a particular pathogen is present, it is present in less than a specified proportion of the population at a given level of statistical confidence.

Disease focus: General

Surveillance that is not focused on specific hazards and that uses general tests (e.g. clinical examination or gross pathology).

Disease focus: Hazard-specific

Surveillance that is focused on one or more pre-defined hazards; often using diagnostic tests for the detection of particular pathogens (e.g. molecular diagnostic tests).

Dissemination method

A description of the methods used for disseminating surveillance information during and after surveillance including whether web-access is possible and the methods used for data sharing.

E

Early warning surveillance

also: epidemiological watch, epidemiovigilance

Surveillance of health indicators and diseases in defined populations to increase the likelihood of timely detection of undefined (new) or unexpected (exotic or re-emerging) threats. These are surveillance systems for the early detection of these threats.

Economic efficiency

Whether the surveillance system produces the desired effect without wasting resources. Three levels of economic efficiency can be defined:

  • Optimisation: maximising the net benefit to society achieved by the allocation of scarce resources to animal health surveillance and intervention to avoid losses resulting from animal diseases
  • Acceptability: ensuring that the benefits generated by a mitigation policy at least cover its costs, this is commonly assessed using cost-benefit analysis
  • Cost-minimisation: ensuring that a technical target for disease mitigation (e.g. time to detection) is achieved at minimum cost without quantifying the benefit in monetary terms, this can be assessed using cost- effectiveness or least-cost analysis
Enhanced passive surveillance

Observer-initiated provision of animal health related data with active investigator involvement e.g. by actively encouraging producers to report certain types of disease or by active follow up of suspect disease reports.

Epidemiological watch

See: Early warning surveillance

Epidemiovigilance

See: Early warning surveillance

Evaluation

The evaluation of a surveillance system/component is the determination of its merit by confronting the results of the assessment with targets set by the stakeholders, standard criteria or a counterfactual system. The outcome of an evaluation is a judgement and/or recommendations placed in the overall surveillance context. An evaluation can be performed at any development stage of the surveillance system. Ideally, an evaluation is conducted in regular intervals in line with the policy cycle, by internal and/or external evaluators. One, several or all components in the surveillance system and any number of attributes and/or criteria can be considered, depending on the question and the context of the evaluation.

Event-based (media-based, digital) surveillance

Surveillance that complements indicator-based surveillance by continuously scanning the Internet and other communication media to detect information that might lead to the recognition of emerging threats. It uses unstructured data which need to be studied and verified and which cannot be summarised as an indicator.

F

False alarm rate

Proportion of negative events (e.g. non-outbreak periods) incorrectly classified as events (e.g.outbreaks). This is the inverse of the specificity but can be more easily understood than specificity.

Flexibility

Ability to adapt to changing information needs or operating conditions with little additional time, personnel or allocated funds. Flexible systems can accommodate new health-hazards, changes in case definitions or technology, and variations in funding or reporting sources.

G

General surveillance

Surveillance that is not focused on specific hazards and uses general tests (e.g. clinical examination or gross pathology). Syndromic surveillance is a form of general surveillance.

H

Hazard

A biological, chemical or physical agent in, or a condition of, an animal or animal product with the potential to cause an adverse health effect.

Source: OIE Terrestrial Animal Health Code
Hazard situation

Endemic, sporadic, free, exotic, re-emerging, new, situation varies

Source: RISKSUR
Hazard-specific surveillance

Surveillance that is focused on one or more pre-defined hazards (disease, condition, biological, chemical or physical agent, or event) often this form of surveillance uses diagnostic tests for the detection of particular pathogens (e.g. molecular diagnostic methods).

 

I

Impact

Indicates the changes that have been made based on the results of the surveillance providing a measur of the usefulness of the surveillance system in relation to its aims. This should include details of actions taken as a result of the information provided by the surveillance system (e.g. changes in protocols or behaviour, changes in mitigation actions and especially changes in disease occurrence.

Indicator-based surveillance

Traditional disease surveillance which relies on the collection of data about the occurrence of pre-defined diseases or conditions and which uses agreed-upon case definitions; these data are analysed to produce indicators that point towards the existence of a threat. Indicator-based surveillance may be hazard-specific or general and includes the use of clinical or other data for syndromic surveillance.

L

Laboratory management

Whether testing is carried out using appropriate methods with quality assurance scheme and timely and accurate delivery of results.

M

Management

also: personnel and organisational structure.

Name of organisation(s) and expertise of the personnel managing the surveillance activity and description of the organisational structure

Monitoring

The systematic, continuous or repeated, measurement, collection, collation, analysis and interpretation of animal health and welfare related data in defined populations when these activities are not associated with a pre-defined risk mitigation plan although extreme changes are likely to lead to action.

Multi-objective

Surveillance activities where samples collected for one disease agent are analysed for more than one purpose or for other disease agents, either in parallel or at a later stage.

Source: RISKSUR (Deliverable 1.1) .
Multiple utility

Whether the system captures information about more than one hazard.

O

Organisation and management

An assessment of organisational structures include whether the objectives are relevant and clearly defined and the existence of steering and technical committees whose members are representative of the surveillance stakeholders. The members of these committees should have appropriate expertise, clearly defined roles and responsibilities; these member should hold meetings (with minutes taken and kept)regularly to oversee the function of the system.

Origin of data: Active

see: Active surveillance

Origin of data: Enhanced passive

see: Enhanced passive surveillance

Origin of data: Passive

see: Passive surveillance

P

Participation, basis of
  • voluntary
  • voluntary recruitment with mandatory participation
  • mandatory
Participatory surveillance

Participatory surveillance explores traditional information networks by using participatory rural appraisal methods such as ranking, scoring and visualisation techniques to conduct risk-based, hazard-specific surveillance. The approach uses semi-structured interviews with key informants. This enables communities to provide their knowledge regarding health events, risks, impacts and control opportunities by gathering qualitative health data from defined populations. The analysis of participatory data emphasises the comparison of information obtained from multiple informants; the method uses a variety of techniques to obtain the most likely interpretation of events. The objective is to enhance sensitivity by identifying cases based on a clinical case definition; these may then be evaluated and confirmed using either rapid tests in the field or laboratory diagnostics. Conventional epidemiological investigation techniques can be used to evaluate and confirm outbreaks detected by participatory surveillance as part of trace-back and trace-forwards activities.

Passive surveillance

Observer-initiated provision of animal health related data (e.g. voluntary notification of suspect disease) or the use of existing data for surveillance. Decisions about whether information is provided, and what information is provided from which animals is made by the data provider.

Pattern of disease occurrence: Endemic

The constant presence of a disease in the population of interest.

Pattern of disease occurrence: Exotic

A previously defined (known) disease that crosses political boundaries to occur in a country or region in which it is not currently recorded as present.

Pattern of disease occurrence: New

also: emerging

A previously undefined (unknown) disease or condition, which might result from the evolution or change in an existing pathogen or parasite resulting in a change of strain, host range, vector, or an increase in pathogenicity. This might also be due to the occurrence of any other previously undefined condition.

Pattern of disease occurrence: Re-emerging

A previously defined (known) disease that is currently either absent or present at a low level, in the population in a defined geographical area that re-appears or significantly increases in prevalence,

Pattern of disease occurrence: Sporadic

A known disease which occurs intermittently in an irregular or haphazard pattern.

Performance monitoring and evaluation

Whether performance indicators are routinely used to monitor system performance and periodic external evaluations are used to assess the system outputs in relation to its objectives.

Policy purpose

Describes how surveillance information is used by policy makers to inform decisions about how best to support policy objectives such as maintaining a healthy and sustainable food and farming industry, protection of the livelihood of producers, other value chain stakeholders and public health and to support national economic development. The specific decisions that surveillance information can assist policy makers with are:

  • Management of outbreaks: whether additional control measures are required to limit the spread of an emerging or exotic disease outbreak
  • Informing trade: whether to permit import or support export of animals or animal products. This decision should be based on evidence about the prevalence and distribution of disease and about the risk of disease transmission through the commodity being traded. The purpose being to protect the indigenous population and facilitate access to international markets
  • Prioritisation: how to prioritise surveillance and control measures for different health hazards. The prioritisation should be based on the level of hazard occurrence and impact on animal health and welfare, public health, trade and the wider economy; the prioritisation should use information about the relative importance of hazards
  • Informing control: whether existing control measures should be maintained, stopped, or changed to improve the efficiency of surveillance and risk mitigation. This may include providing reassurance about the absence of specific existing or new diseases (which could threaten animal health or welfare or public health) to confirm that risk mitigation is not required.
Precision

How closely defined a numerical estimate is. A precise estimate has a narrow confidence interval. Precision is influenced by prevalence, sample size and surveillance system quality.

Proactive surveillance

see: Active surveillance

R

Reactive surveillance

see: Passive surveillance

Repeatability

How consistently the study results can be reproduced over time.

Representativeness

The extent to which the features of the population of interest are reflected by the population included in the surveillance activity. These features may include herd size, production type, age, sex or geographical location or time of sampling (important for some systems e.g. for vector-borne infection).

Requirement

Input-based standards prescribe the surveillance activities to be carried out (i.e. sampling strategy, sample size, choice of test and frequency of testing), assuming that the population properties of herds are homogeneously distributed. Output-based standards prescribe what surveillance has to achieve, thus providing flexibility required to find the most effective surveillance approach for the specific population under surveillance.

Source: Cameron, 2012: PVM 2015, p. 280-286
Resource availability

An assessment of the financial and human resources available for implementing the surveillance activity including the expertise and capability of personnel.

Risk

The likelihood of the occurrence and the likely magnitude of the biological and economic consequences of an adverse event or effect to animal or human health.

Source: OIE Terrestrial Animal Health Code
Risk factor assessment

The evaluation of the likelihood and the biological and economic consequences of entry, establishment and spread of a hazard within the territory of a country.

Source: OIE Terrestrial Animal Health Code
Risk factors
  • geography
  • animal
  • management
  • environmental  or other factors
  • + free text to describe
Source: RISKSUR
Risk-based analysis

Use of prior or additional information about the probability of hazard occurrence, including contextual information and prior likelihood of disease to revise conclusions about disease status.

Risk-based prioritisation

Determining which hazards should be selected for surveillance based on information about the probability of their occurrence and the extent of biologic and/or economic consequences of their occurrence.

Risk-based requirement

Use of prior or additional information about the probability of hazard occurrence to revise the surveillance intensity required to achieve the stated surveillance purpose.

Risk-based sampling

Designing a sampling strategy to reduce the cost or enhance the accuracy of surveillance by preferentially sampling strata (e.g. age groups or geographical areas) within the target population that are more likely to be exposed, affected, detected, become affected, transmit infection or cause other consequences (e.g. large economic losses or trade restrictions).

Risk-based surveillance

Use of information about the probability of occurrence and the magnitude of the biological and/or economic consequence of health hazards to plan, design and/or interpret the results obtained from surveillance systems. Risk-based surveillance can include one or several of the following four approaches:

  • Risk-based prioritisation
  • Risk-based requirement
  • Risk-based sampling
  • Risk-based analysis

S

Sample type(s)
  • blood / plasma / serum
  • animal swab, tissue
  • carcass
  • faeces
  • urine
  • semen
  • milk / colostrum
  • environmental sample
  • clinical surveillance
  • post-mortem
Source: RISKSUR
Sampling strategy

Use of appropriate sampling strategies including the use of risk-based approaches (i.e. risk-based requirement calculation or risk-based sampling) and pooled sampling where appropriate. The basis of the risks used in the design of the risk-based sampling strategy should be assessed.

Scope of surveillance activity: Component

A single surveillance activity (defined by the source of data and the methods used for its collection) used to investigate the occurrence of one or more hazards in a specified population.

Scope of surveillance activity: Portfolio

A range of surveillance components (and the associated organisational structures) used to investigate the occurrence of more than one hazard in a specified population.

Scope of surveillance activity: System or network

A range of surveillance components (and the associated organisational structures) used to investigate the occurrence of a single hazard in a specified population.

Sensitivity

Sensitivity of a surveillance system can be considered on three levels:

  • Surveillance sensitivity: Case detection
  • Surveillance sensitivity: Outbreak detection
  • Surveillance sensitivity: Presence
Sentinel surveillance

The repeated collection of information from the same selected sites or groups of animals (e.g. veterinary practices, laboratories, herds or animals) to identify changes in the health status of a specified population over time. These sentinels should act as a proxy for the larger population of interest; they may be selected on the basis of risk but can also be selected randomly or on the basis of convenience or compliance.

Simplicity

Refers to the surveillance system structure, ease of operation and flow of data through the system.

Stability and sustainability

The ability to function without failure (reliability), the ability to be operational when needed (availability) and the robustness and ability of the system to be ongoing in the long term (sustainability).

Stakeholders

also: owners and beneficiaries.

Name of organisation(s) paying for the surveillance activity and identification of beneficiaries.

Study design
  • Case reporting (voluntary or mandatory)
  • Survey
  • Continuous collection
  • Participatory
  • Sentinel
  • Event-based (media-based)
Surveillance

The systematic, continuous or repeated, measurement, collection, collation, analysis, interpretation and timely dissemination of animal health and welfare related data from defined populations. These data are then used to describe health hazard occurrence and to contribute to the planning, implementation, and evaluation of risk mitigation actions.

Surveillance objective

states those goal(s) that when met will result in the collection and analysis of data in order to achieve the purpose of the system (OIE 2014a).

Surveillance purpose

describes why surveillance is necessary and what it will accomplish (OIE 2014a).

Surveillance sensitivity: Case detection

The proportion of individual animals or herds in the population of interest that have the health-related condition of interest and that the surveillance system is able to detect.

Surveillance sensitivity: Outbreak detection

The probability that the surveillance system will detect a significant increase (outbreak) of disease. This requires a clear definition of what constitutes an outbreak.

Surveillance sensitivity: Presence

The probability that disease will be detected if present at a certain level (prevalence) in the population.

Syndromic surveillance

Surveillance that uses health-related information (clinical signs or other data) that might precede or substitute for formal diagnosis. This information may be used to indicate a sufficient probability of a change in the health of the population to deserve further investigation or to enable a timely assessment of the impact of health threats which may require action. This type of surveillance is not usually focused on a particular hazard so can be used to detect a variety of diseases or pathogens including new (emerging) diseases. This type of surveillance is particularly applicable for early warning surveillance.

T

Timeliness

Timeliness can be defined in various ways:

Usually defined as the time between any two defined steps in a surveillance system. The time points chosen are likely to vary depending on the purpose of the surveillance activity. For outbreak detection this can be defined using various time points (e.g. the time between exposure to the infectious agent and the initiation of risk-mitigation measures or the time between when disease could have been detected and reported and the time when it actually was reported).

For planning purposes, timeliness can also be defined as whether surveillance detects changes in time for risk-mitigation actions to reduce the likelihood of further spread. One way of measuring this would be to assess the number of cases present in the population when disease was detected.

The precise definition of timeliness chosen should be stated as part of the evaluation process.

Training provision

Provision of adequate initial training and an ongoing program of training for those implementing the surveillance system.

U

Unit of interest

Units selected for sampling in surveillance activity (level of sampling).

e.g. animal, farm, batch, village