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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 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:

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 OIE 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:

3.4.1.3 Presumptive Case

A presumptive case of ND is defined as follows:

or

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:

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:

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 OIE 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

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:

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

Restricted Zone (a radius of 10 km from the 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

Restricted Zone

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 OIE.

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:

Restricted zone

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

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

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