3. Authorities and Principles of Control

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3.1 Purpose

Canada's primary policy for ND in domestic poultry is stamping out, which includes the possible use of pre-emptive slaughter to stop the outbreak and possible secondary outbreaks, as well as to prevent related economic and genetic losses.

3.2 Statutory Authority

Statutory authority for the control of ND is contained in the Health of Animals Act (1990 c. 21).

3.3 Statement

The CFIA is committed to safeguarding food, animals, and plants, which enhances the health and well-being of Canada's people, the environment, and the economy. To achieve this, the CFIA developed a control policy that is based on stamping out. To this end, the CFIA may prescribe mandatory vaccination under certain outbreak consideration factors, geographic situations, and management practices, and thus would serve as an addition to stamping out and pre-emptive slaughter, in an effort to temporarily control the spread of the virus until stamping out can eliminate the presence of ND virus in domestic poultry.

3.4 Principles of Control in Poultry

3.4.1 Newcastle Disease Case Definition

3.4.1.1 Canadian Food Inspection Agency Definition

In an international poultry disease control context, ND viruses are defined by the World Organisation for Animal Health (WOAH; founded as Office International des Épizooties (OIE)), whose definitions have been adopted by the CFIA:

Newcastle disease (ND) is defined as an infection of poultry caused by a virus (NDV) of avian paramyxovirus serotype 1 (APMV-1) that meets one of the following criteria for virulence:

  • the virus has an intracerebral pathogenicity index (ICPI) in day-old chicks (Gallus gallus) of 0.7 or greater; or
  • multiple basic amino acids have been demonstrated in the virus (either directly or by deduction) at the C-terminus of the F2 protein and phenylalanine at residue 117, which is the N-terminus of the F1 protein. The term ‘multiple basic amino acids' refers to at least three arginine or lysine residues between residues 113 and 116. Failure to demonstrate the characteristic pattern of amino acid residues as described above would require characterisation of the isolated virus by an ICPI test.

To date, using these criteria, only infections with velogenic or mesogenic ND viruses have been classified as ND.

Currently, under the Health of Animals Act (Reportable Diseases List), the only reported ND form is the velogenic form. This regulation meets the WOAH reporting requirements, as it requires a virus isolate of ND to be sent to the National Centre for Foreign Animal Diseases (NCFAD) in Winnipeg to determine its pathogenicity (characterization from tracheal and cloacal swabs, or embryonated eggs). This process allows the CFIA to become aware of the presence of all ND detected in Canada, regardless of the pathogenicity.

The minimum criteria for identification of ND-infected flocks are the detection of APMV-1, as determined by RRT-PCR; however, the disease control activities related to the case definition may evolve in the course of an outbreak.

3.4.1.2 Suspect Case

A suspect case of ND is defined by the following:

  • clinical signs or post-mortem lesions confirmed to be compatible with ND by a private practitioner, owner, pathologist, or the veterinarian in charge (VIC), in collaboration with the Area FAD program officer.

3.4.1.3 Presumptive Case

A presumptive case of ND is defined as follows:

  • a non-negative result to PCR (matrix, fusion) from an approved Newcastle Disease Canadian Animal Health Surveillance Network Laboratory (ND-NL);

or

  • one of the suspect criteria described in section 3.4.1.2 is met, in addition to at least two of the following criteria:
    • significant epidemiological contact with a known infected premises; or
    • high mortality; or
    • non-negative result to the detection of APMV-1 (RRT-PCR).

3.4.1.4 Confirmed Case

A confirmed ND case is defined by isolation of the APMV-1 virus and followed by a determination of its pathogenicity by NCFAD, based on the CFIA definition.
In circumstances wherein the virus cannot be isolated, infection with an ND virus can be confirmed through a combination of other diagnostic tools if the investigation is associated with a clinical history. This approach will be assessed by NCFAD, in consultation with epidemiologists and review of field evidence, on a case-by-case basis.

3.4.2 Principles of Control

All ND cases are reported to the CFIA for further characterization, regardless of apparent pathogenicity. All velogenic cases of the virus are reportable to the CFIA. In most situations, Canada's stamping-out policy applies.

For an effective stamping-out initiative, the overall purpose is to:

  • rapidly identify all exposed premises;
  • apply strict movement control;
  • trace and destroy all infected or potentially infected animals, products, and materials;
  • clean and disinfect infected premises and vehicles to avoid further spread; and
  • regain Canada's ND country freedom status without delay.

This policy is only sustainable where available resources can eliminate infected birds faster than the disease is spreading. If stamping out is impractical, long-term control options (e.g. mandatory vaccination) will be discussed with industry. If the disease becomes endemic, infected poultry would be slaughtered at industry cost, and individual flock certification of freedom would be implemented. All economic factors must be considered in the decision to abandon the stamping-out policy.

3.4.3 Biocontainment

The CFIA is responsible for eradicating ND outbreaks in poultry. CFIA personnel or any other person who must enter premises that are declared infected must follow established biocontainment rules to prevent the virus from spreading beyond these premises. Those who require entry to infected premises must demonstrate that they have the necessary biocontainment competencies before being authorized to work in a contaminated environment.

In addition to full compliance with the established protocols, these rules include:

  • wearing personal protection equipment (PPE);
  • decontaminating objects that must be removed from the infected premises;
  • exiting the infected premises or suspect premises following the established procedure; and
  • having no contact with other susceptible species for at least 24 hours following entry to the infected premises.

The Biocontainment and Biosecurity Unit is responsible for ensuring that these rules are followed during the control and response operations (i.e. euthanasia, slaughter, destruction, disposal, cleaning, and decontamination). A biocontainment and biosecurity coordinator is assigned to the Emergency Operations Centre (EOC), and biocontainment and biosecurity officers are assigned to each of the premises from the start of operations to their cessation. Biocontainment and biosecurity officers are also responsible for implementing an internal audit system on the compliance of personnel and the implementation of biocontainment and biosecurity measures in the Primary Control Zone (PCZ).

3.4.4 Definition of Commercial and Non-Commercial Poultry Flock

The role of non-commercial flocks in the spread of ND must be defined in consideration of species susceptibility, size of the flocks, location, and the degree of interaction between this sector and the commercial poultry industry in all Canadian provinces.

The WOAH does not define non-commercial flocks; however, its definition of poultry clearly includes both commercial and non-commercial operations:

…all domesticated birds, including backyard poultry, used for the production of meat or eggs for consumption, for the production of other commercial products, for re-stocking of game, or for breeding these categories of birds, as well as fighting cocks used for any purpose.

Based on the husbandry characteristics of non-commercial flocks and the potential contact between non-commercial and commercial flocks, the commercial poultry sector must adopt and employ mandatory auditable and verifiable standards that ensure effective barriers among commercial, non-commercial, and wild bird populations. The CFIA is presently partnering with industry in developing a biosecurity structure, including an audit process, for the poultry industry. With a biosecurity structure in place, one could characterize non-commercial operations as a population that, if infected, would not pose a risk to the commercial poultry sector.

Still, work remains to better characterize the non-commercial poultry sector in Canada. In the interim, the CFIA, in accordance with the Poultry Expert Committee, has defined commercial and non-commercial poultry as follows:

Non-commercial poultry

Poultry raised on a premises with fewer than 300 domestic birds that are kept as pets, including show birds and rare breeds, or raised for the owner's consumption and use only.

Commercial poultry

  • Poultry that are raised under Canada's supply management (quota) system or for the purpose of selling its products and by-products for financial gain outside the quota system.
  • Poultry raised on a premises with 300 or more domestic birds, even if there are no commercial activities.

3.4.5 Risk Assessment

The CFIA's disease response follows a risk-based approach. Priority is given to operations that pose the greatest risk of disease spread or amplification. An assessment grid, including factors such as affected species, distance from a known infected premises, management practices, and many other epidemiological elements, can assist in estimating the risk of a particular flock becoming infected by ND and in determining the risk of that flock spreading the disease.

3.4.6 Risk Management

As biosecurity and biocontainment measures in the non-commercial sector are not well established, any non-commercial poultry flock infected with the APMV-1, regardless of the pathogenicity, must be considered at risk of transmitting the ND virus to commercial or other non-commercial flocks. If galliformes are exposed to these viruses, there is the possibility the virus may adapt, eventually mutate in a slow and infrequent way compared with notifiable avian influenza (NAI) viruses, and may develop increased pathogenicity over time,. Any poultry flock infected with ND, as well as any significant contact flock that becomes infected, should be destroyed.

3.4.7 Zoning for Newcastle Disease

3.4.7.1 Zoning before the Declaration of a Primary Control zone

Before the Declaration of a PCZ (if appropriate) by the Minister, a zone around known infected premises may be considered:

Initial Infected Zone: a 3-km zone surrounding an infected premises.
The delineation of the area may vary, depending on physical and geographic boundaries, the apparent progression of the outbreak, the density of poultry population, and poultry production types (commercial and non-commercial).

3.4.7.2 Zoning after the Declaration of a Primary Control Zone

Following the Declaration of a PCZ (if appropriate) by the Minister, the disease control zones will be established as follows:

  • Infected Zone: A zone, or zones, established pursuant to the Health of Animals Regulations that includes all the ND-positive premises. The outer boundary of an Infected Zone is 3 km from any known infected premises. The delineation of the area may vary, depending on physical and geographic boundaries, and according to the progression of the outbreak.
  • Restricted Zone: A zone surrounding the Infected Zone that is established immediately, and measured based on the epidemiology of the disease under consideration to prevent the spread of the causative animal pathogen. The outer boundary of this zone will be at least 10 km from any known infected premises.
  • Security Zone: The geographic area between the perimeter of the Restricted Zone and the edge of the PCZ. This zone is controlled and referred to as a "Security Zone" to prevent confusion when the rest of the country is referred to as "Free."

A Secondary Control Zone (SCZ) may be declared by the minister as a buffer around the PCZ or to prevent introduction of a disease into Canada.

3.5 Actions in the Vicinity of an Infected Place

Prior to the Ministerial Declaration that is made under Section 27 of the Health of Animals Act to define a PCZ, a general provision exists under Section 23 of the Act to individually declare Infected Place (quarantine) on all premises within 5 km of the limits of a premises where the disease has been suspected, presumed, or confirmed. For ND, the size of this area under Section 23 of the Act will be 3 km, and is referred to as the Infected Zone. This Infected Place declaration is an interim measure until the PCZ is enacted and movement control zones are defined, if required. It is anticipated that as soon as the virus is determined a velogenic APMV-1 by NCFAD, the Ministerial Declaration will be made to define a PCZ.

Premises where NDV is detected will be declared an Infected Place, and the poultry and poultry products will be ordered destroyed. The radius of the Infected Zone is 3 km.

3.5.1 Newcastle Disease in Commercial Poultry

For any ND detected in commercial poultry, the CFIA systematically establishes an Infected Zone, and the following actions are taken.

Infected Zone

  • Issue a Declaration of Infected Place on the following:
    • all commercial poultry premises located in the Infected Zone; and
    • significant contact premises, including non-commercial, with the priority for declaration based on proximity and production type (similar production types declared first).
  • Based on the situational assessment, undertake pre-emptive depopulation through destruction of all commercial poultry flocks within a 1-km radius of the index premises. Depopulation priority is based on the following order:
    • premises that have significant epidemiological contact with known infected premises, a particular attention is given to premises with similar production type,
    • premises located at the periphery of the Infected Zone, before premises in the centre.

    Collect samples for virology at the time of destruction.

  • Identify non-commercial poultry premises located in the Infected Zone. Declare as Infected Places, if required, based on these risk factors:
    • proximity to a known infected premises,
    • density of poultry population, and
    • any other relevant epidemiological information.
  • Conduct surveillance in commercial galliformes and anseriformes as follows:
    • baseline surveillance;
    • dead bird surveillance twice a week for three weeks;
    • weekly status report of flocks located on premises declared Infected Places; and
    • pre-movement surveillance.
  • Lift the restriction on premises declared Infected Places, following quarantine release surveillance, with negative results 21 days after the disposal of birds on the known infected premises.

Restricted Zone (a radius of 10 km from the infected premises)

  • Identify all commercial and non-commercial poultry premises.
  • Provide information to the owner on clinical signs of ND and the call-in numbers to report any sick birds (sick calls).
  • Conduct surveillance in commercial galliformes and anseriformes as follows:
    • dead bird surveillance once per week for three weeks; and
    • pre-movement surveillance.
  • Lift the restriction on premises declared Infected Places, following quarantine release surveillance with negative results 21 days after the destruction of birds on the known infected premises.

3.5.2 Newcastle Disease in Non-Commercial Poultry

For any ND detected in non-commercial poultry, the CFIA takes the following actions:

Infected Zone

  • Base depopulation of premises located in the Infected Zone on epidemiological information, proximity, and density of the poultry population in the vicinity of the non-commercial infected flock.
  • Based on the situational assessment carry out pre-emptive depopulation of premises that have had significant epidemiological contact with known infected premises.
  • Issue a Declaration of Infected Place on the following:
    • all commercial poultry premises located in the Infected Zone; and
    • on significant contact premises, including non-commercial; priority for declaration is based on proximity and production type (with similar production types declared first).
  • Identify non-commercial poultry premises located in the Infected Zone. They would be declared Infected Places, if required, based on these risk factors:
    • proximity to a known infected premises,
    • density of poultry population, and
    • any other relevant epidemiological information.
  • Conduct surveillance in commercial galliformes and anseriformes as follows:
    • baseline surveillance;
    • dead bird surveillance once a week for three weeks or twice a week if risk assessment warrants;
    • weekly status report of flocks on premises declared Infected Places; and
    • pre-movement surveillance.
  • Lift the restriction on premises declared Infected Places, following quarantine release surveillance with negative results 21 days after the disposal of birds on the known infected premises.

Restricted Zone

  • Identify all commercial and non-commercial poultry premises.
  • Provide information to the owner on clinical signs of ND and the call-in numbers to report any sick birds (sick calls).
  • Lift the restriction on premises declared Infected Places, following quarantine release surveillance, with negative results 21 days after the destruction of birds on the known infected premises.

3.5.3 Newcastle Disease in Wild Birds

Wild birds are natural reservoirs for ND viruses, and the majority of these viruses circulate in wild birds with little or no impact on their health. Some of these viruses, particularly the velogenic subtypes, represent a threat to domestic poultry when introduced into domestic poultry flocks.

When samples are submitted during the investigation of a large die-off of wild birds, or when there is clinical evidence of ND in wild birds and the subsequent results confirming that ND is present become available in a timely manner, the CFIA notifies the poultry boards and possibly the domestic poultry owners in the vicinity of the finding. The CFIA stresses the need for enhanced biosecurity measures, if these are not already in place. Specifically, the CFIA recommends that domestic flocks, as well as their food and water, be kept indoors. The CFIA reports such findings every 6 months to the WOAH.

For any ND, the following actions will be taken:

Infected zone

The CFIA establishes an Infected Zone with a radius of 3 km from the location of a ND-positive wild bird detection and carries out the following activities:

  • Provide a Declaration of Infected Place in poultry operations, commercial and non-commercial, based on risk assessment.
  • Conduct surveillance for commercial operations of galliformes and anseriformes as follows:
    • dead bird surveillance once per week for three weeks;
    • sick bird investigation;
    • weekly status report of flocks located on premises declared Infected Places; and
    • pre-movement surveillance.
  • Note that surveillance for non-commercial operations of galliformes includes only sick calls.
  • Lift the restriction on premises declared Infected Places, following quarantine release surveillance, with negative results 21 days after detecting ND virus in a wild bird.

Restricted zone

With a radius of 10 km from the location of a ND wild bird detection, the following surveillance activities take place:

  • For commercial operations of galliformes and anseriformes, surveillance includes these activities:
    • sick bird investigation; and
    • weekly status report of flocks located on premises declared Infected Places.

The described response to ND detection in a wild bird population may be modified according to the parameters that are available during the investigation:

  • the time from sample collection to the final test results;
  • the sample origin (die-off, dead bird, or live healthy bird);
  • the wild bird species affected;
  • the distribution area of that species;
  • resident or migratory birds; and
  • the period of the year (e.g. migration, nesting, or wintering).
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