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Animal and Plant Health Inspection Service
U.S. Department of Agriculture
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Glossary

  • Test methods considered in the OIE Terrestrial Manual that are suitable for the diagnosis of disease in a local situation, and that can also be used for import/export by bilateral agreement.
  • Premises located in the Control Area with susceptible animals, but none have clinical signs compatible with the FAD.  Premises objectively demonstrates that it is not an Infected Premises, Contact Premises, or Suspect Premises. At-Risk Premises seek to move susceptible animals or products within the Control Area by permit. Only At-Risk Premises are eligible to become Monitored Premises. More information on Premises Classification.
  • Zone immediately surrounding the Infected Zone or a Contact Premises. The BZ is a scalable area with a width that is never less than the width of the IZ, but may be much larger than the IZ. The width of the BZ may be as small as 4.35 mi (7km) beyond the perimeters of the IZ. Width is generally not less than the minimum radius of the associated IZ, but may be much larger. The size of the BZ and CA depends upon the FAD agent and circumstances of the outbreak. The BZ may initially be as large as a county, township, district, regional area, State, Tribal Nation, or other jurisdictional level. The boundaries of the BZ can be modified or redefined as needed by the circumstances of the outbreak. Toolbox information on Disease Control Zones
  • An individual in a population or study group identified as having a particular disease or other health related event that is being investigated, with or without clinical signs.
  • A set of diagnostic criteria that must be fulfilled in order to identify an individual as a case of a particular disease. Case definition can be based on clinical, laboratory, or combined clinical and laboratory criteria.
  • Can be used to broaden or restrict the sensitivity of a surveillance system by designating the species of animal(s) under surveillance and inclusion or exclusion of clinical signs or lesions for the disease or condition under investigation. Clinical case definition may be used to screen animals for additional testing.
  • Animal is housed with an animal that is a confirmed case of the disease in question or having a high likelihood of direct contact with the confirmed case.
  • A highly specific test (high diagnostic specificity) designed to confirm the results of an earlier (screening) test, these tests are typically less rapid and more difficult to perform, are less readily available within a laboratory system because of additional expertise needed to perform the test, and are more expensive than more commonly used screening tests. The ideal confirmatory test should be highly specific. This test may be performed in an official laboratory, depending on the disease agent.
  • A case that is laboratory confirmed with a confirmatory test
  • Isolation of the pathogen (influenza A virus identified as an H5 or H7 subtype for example) and determination of pathogenicity by the NVSL (HPAI or H5/H7 LPAI for example).
  • Premises with susceptible animals that may have been exposed to the foreign animal disease (FAD) agent,  either directly or indirectly, including but not limited to exposure to animals, animal products, fomites, or people from Infected Premises. Contiguous premises in close proximity to an Infected Premises may also be classified as a CP. A CP identified outside the Control Area must be surrounded by a Buffer Zone until the disposition of the CP is determined. More information on Premises Classification.
  • Emergency Vaccination Zone typically within the Control Area and may include all or part of the IZ and/or BZ. CVZ is a secondary zone designation. Quarantine and movement control requirements, surveillance requirements, and biosecurity procedures for the CA apply to the CVZ. Toolbox information on Disease Control Zones
  • Consists of an Infected Zone and a Buffer Zone. The size of the CA depends upon FAD agent and circumstances of the outbreak. The CA radius may be as small as 6.2 miles (10 km) beyond the perimeter of the closest Infected Premises. The CA may be much larger, such as a jurisdictional unit, geographic area, or region. The size of the CA is scalable to the risk posed by the disease agent and the circumstances of the outbreak. Toolbox information on Disease Control Zones.
  • An animal showing no clinical signs of disease but which, by reason of its probable exposure to disease, may be subjected to disease control measures (which may require slaughter of all or some of such animals).
  • The clinical and/or pathological manifestation of infection.
  • Disease Reporting Officer
  • The study of a disease pattern in a population to determine prevention and control strategies.
  • An epidemiological link exists when two disease positive animals share a common risk factor that explains where and when the disease agent could have been transmitted between them. An epidemiologic link could be a common herd of origin or a location where the two animals were housed together or co-mingled.
  • An animal or a group of animals that share a common exposure to a pathogen. This may be because they share a common environment or because of common management practices. Usually, this is a herd or a flock. However, an epidemiological unit may also refer to groups such as animals belonging to residents of a village, or animals sharing a communal animal handling facility. The epidemiological relationship may differ from disease to disease, or even strain to strain of the pathogen.
  • The premises in which animals are housed.
  • Conditions which preclude entrance of candidates into an investigation even if they meet the inclusion criteria.
  • Foreign Animal Disease
  • USDA, APHIS, Veterinary Services, Foreign Animal Disease Diagnostic Laboratory, Plum Island, New York

The FA is an area in which the absence of the disease under consideration has been demonstrated by meeting requirements for “surveillance to demonstrate freedom from disease/infection” as specified in Chapter 1.4 of the OIE Terrestrial Animal Health Code 2017.

  • Test that is independent and valid that is used to determine the true disease status of an animal and to define the sensitivity and specificity of other tests, often widely accepted as being the best available.
  • Highly contagious disease
  • An individual in which a disease agent invades and multiplies in body tissue
  • An infected individual capable of transmitting the disease agent
  • Premises where a presumptive positive case or confirmed positive case exists based on laboratory results, compatible clinical signs, case definition, and international standards. More information on Premises Classification.
  • Zone immediately surrounding the Infected Premises. The IZ will initially encompass the perimeter of all presumptive or confirmed positive premises and include as many of the Contact Premises or contiguous premises as required epidemiologically or logistically. The IZ radius may be as small as 1.86 miles (3 km) radius beyond the perimeters of the presumptive or confirmed Infected Premises. The size of the IZ depends upon the FAD agent and circumstances of the outbreak. The IZ may initially be as large as a county, township, district, regional area, State, Tribal Nation, or other jurisdictional level. The boundaries of the IZ can be modified or redefined as needed by the circumstances of the outbreak. Toolbox information on Disease Control Zones.
  • Premises located in the Control Area that objectively demonstrates it is not an Infected Premises, Contact Premises, or Suspect Premises. Only At-Risk Premises are eligible to become Monitored Premises. Monitored Premises meet a set of defined criteria in seeking to move susceptible animals or products out of the Control Area by permit. More information on Premises Classification
  • National Agricultural Statistical Service
  • USDA, APHIS, Veterinary Services, National Veterinary Services Laboratory, Ames, IA
  • The probability that the animal is not diseased (healthy), given that a diagnostic test is negative. For a given sensitivity (Sn) and specificity (Sp) of a diagnostic test, NPV is negatively correlated with prevalence of disease, i.e. if prevalence of disease decreases the NPV of the diagnostic test increases and if prevalence of disease increases the NPV of the diagnostic test decreases.
  • The occurrence of disease in an agricultural establishment, breeding establishment or premises (non-agriculture) where animal(s) are housed, including all buildings as well as adjoining premises, where animals are present.
  • Non-systematic, opportunistic sampling of clinical or subclinical suspect cases, or non-clinical cases of a population; this method relies primarily on producers and practitioners to report suspect cases.
  • The probability that the animal is diseased, given that a diagnostic test is positive. For a given sensitivity (Sn) and specificity (Sp) of a diagnostic test, PPV is positively correlated with prevalence of disease, i.e. if prevalence of disease decreases the PPV of the diagnostic test also decreases and if prevalence of disease increases the PPV of the diagnostic test also increases.
  • Synonymous with negative predictive value (NPV) of a diagnostic test.
  • Synonymous with positive predictive value (PPV) of a diagnostic test.
  • The physical site where the subjects of an investigation or sample collection are located.
  • Test methods that are required by the OIE Terrestrial Animal Health Code or other Official Source for the international or National movement of animals and animal products and that are considered optimal for determining the health status of animals.
  • Meets the criteria of a suspect case and further testing indicates infection with pathogen is likely, but the pathogen has not been isolated or positive on officially accepted test or by an accredited laboratory. May vary with disease, for example; Avian Influenza presumptive cases require suspect case criteria and detection of antibodies that cannot be explained with vaccination, detection of antigen, or RNA identification with PCR (see AI Surveillance plan for more details).
  • The prevalence of a disease is the proportion of a population that are cases at a point in time.

The PVZ is consistent with the (OIE) Terrestrial Animal Health Code 2017 definition for a Protection Zone. A Protection Zone is defined by the OIE as “a zone established to protect the health status of animals in a free country or free zone, from those in a country or zone of a different animal health status, using measures based on the epidemiology of the disease under consideration to prevent spread of the causative pathogenic agent into a free country or free zone. These measures may include, but are not limited to, vaccination, movement control and an intensified degree of surveillance.

  • Enforced isolation or restriction of the free movement of an animal or animal product, imposed to prevent an agent from spreading.
  • Vaccination of all susceptible animals around a focus of infection to provide a buffer against the spread of disease.
  • The likelihood and magnitude (of the consequences) of occurrence of an adverse event; a measure of the probability of harm and the severity of the adverse effects.
  • Material that is derived from a specimen and used for testing purposes.
  • List of all sampling units in the sampled population.
  • The division of the population to be sampled into easily recognizable units such as individual animals or an aggregate of individuals, such as herds, pens, or litters.
  • Generally performed rapidly, are usually widely available within a laboratory system, and are relatively inexpensive. These tests typically trade lower specificity for higher sensitivity, which results in some level of false positive results. False negatives are undesirable, but may occur. These tests are of high diagnostic sensitivity suitable for large-scale application.
  • Proportion of reference animals with disease that have a positive test result; this is the proportion of true positives that are correctly identified by the test.
  • Proportion of reference animals free of a disease that have a negative test; this is the proportion of true negatives that are correctly identified by the test.
  • Eradication procedures based on quarantine and slaughter of all infected animals and animals exposed to infection.
  • The ongoing systematic collection, analysis, and interpretation of disease data essential to the planning, implementation, and evaluation of animal disease management, closely integrated with the timely dissemination of these data to decision makers and policymakers.
  • A document that describes a surveillance system including disease description, the purpose, rationale, objectives, and outcomes; stakeholders and responsible parties; population and sampling methods; performance metrics; plans for analysis, reporting, and presentation; and expected implementation, budgeting, and evaluation plans needed to develop a surveillance system.
  • Zone established outside and along the border of the Control Area (CA), separating the Free Area (FA) from CA. Surveillance in the SZ will focus on premises determined to be at the highest risk of infection. The width of the SZ should be at least 6.2 mi (10 km). The maximum size of the SZ may be much greater.  Toolbox information on Disease Control Zones
  • Animal meets epidemiologic criterion or has clinical signs that are consistent with the disease of interest. Following epidemiological investigation, surveillance requirements, and biosecurity requirements, a SP can be designated as an At-Risk or Monitored Premises if in a Control Area, or as a Free Premises if in a Free Area.
  • Premises under investigation due to the presence of susceptible animals reported to have clinical signs compatible with the FAD. This is intended to be a short-term premises designation. Suspect premises are located in the Infected Zone, Buffer Zone, Surveillance Zone, or Vaccination Zone. More information on Premises Classification.
  • Premises where emergency vaccination has been performed. This is a secondary premises designation. The primary premises designation will be IP, CP, ARP, MP if located in the Control Area, or FP if located in the Free area. Vaccinated Premises may be located in the Containment Vaccination Zone, typically within the Control Area, or in the Protection Vaccination Zone, typically outside the Control Area. More information on Premises Classification.
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