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3. Comparative > Poultry 1 > Flashcards

Poultry 1 Flashcards

1
Q

The four poultry diseases/agents reportable to CFIA in Canada are:

A
  • Notifiable avian influenza (NAI [H5 and H7 subtypes])
  • velogenic pathotype of
  • Newcastle disease virus,
  • typhoid salmonellae (S. Pullorum and S. Gallinarum).
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2
Q
  • Poultry operations in Canada (and US) are free of H5/H7 (notifiable) avian influenza, velogenic NDV, S. Pullorum and S. Gallinarum.
  • Therefore, Canada has a “free” status for these diseases.
  • what happens if these pathogens are diagnosed in poultry in canada?
A

If these pathogens are diagnosed in poultry, depopulation is mandatory.

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3
Q

AIV - GENERAL FEATURES
- type of virus
- family
- what does HA do? what does it determine?

A

*Influenza A virus. *Orthomyxoviridae family.
*18 Hemagglutinin (HA) subtypes.
*11 Neuraminidase subtypes (NA).
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*HA allows entrance of the virus in the cells.
*HA is a determinant of virulence.
*Birds susceptible to 1-16 HA subtypes

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4
Q

what needs to happen for AIV infection to occur? what determines virulence?

A

The HA protein needs to be activated (i.e., cleaved) by tissue (host) enzymes for infection to occur. How easily the HA can be activated in tissues determines the virulence of AIV strains.

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5
Q

non-virulent strains vs virulent strains of AIV
- what determines the difference?
- which strains are virulent? in what species?

A

NON-VIRULENT STRAINS:
* HA is activated only in the respiratory and intestinal tracts, leading to localized infection (LPAI).
* Non virulent HA subtypes H5 and H7 can mutate and acquire a virulent configuration.
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VIRULENT STRAINS:
* HA is activated in multiple tissue > systemic replication > severe disease (HPAI).
* Only the HA subtypes 5 and 7 (H5 and H7) can have a virulent configuration.
* H5 and H7 AIV strains circulate only in avian species.

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6
Q

influenza epidemiology in poultry - which strains circulate in water fowl? how do they become problematic?

A

LPAIV H5 or H7 strains circulate in waterfowl and are transmitted to poultry.
> LPAIV strains circulate in poultry with mild disease.
> LPAIV mutates (antigenic drift) to HPAIV > severe disease.

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7
Q

which AIV strains are notifiable? why?

A

The mutation from a non virulent to a virulent configuration of the HA protein has been only described for H5 and H7 subtypes.
Therefore, all H5 and H7 AIV strains are considered to be notifiable (NAI = reportable in Canada), regardless if HPAIV or LPAIV.

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8
Q

what two mechanisms drive influenza mutation? how do they work?

A
  1. AntigenicDrift:
    – Accumulation of small mutations;
    – Point mutations in HA gene;
    – Gradual changes in antigenicity.
  2. Antigenic Shift:
    – Assortment of genes between different
    virus strains;
    –Sudden change of HA gene;
    – New subtypes generated;
    – Explosive spread (no population immunity).
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9
Q

Mutation from a LPAIV to a HPAIV strain is mediated by antigenic drift or shift?

A

drift

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10
Q

difference of HPAI pathogenesis
- where does it replicate?

A

Virus replicates in endothelium and multiple parenchymas / tissues
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The pathogenesis (how the disease progress in the body) is very different between HPAIV and LPAIV strains.

After initial respiratory or oro-fecal transmission, HPAIV replicate in the vascular endothelium. After initial replication in endothelial cells, if the bird survives, there is replication in multiple parenchymas, leading to multiorgan failure.

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11
Q

what lesions can we see associated with the propensity of HPAI to replicate in endothelium

A

Hemorrhages and marked edema are consequences of loss of vascular integrity due to virus replication in the endothelium.
- facial edema
- comb cyanosis
- cutaneous hemorrhages
- etc.
<><>
Petechial hemorrhages in the epicardium are often observed > caused by replication within the endothelium

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12
Q

are waterfowl resistant to HPAI or do they get lesions

A

Usually waterfowl species can be resistant even to HPAIV, but the new Asian H5N1 strain that emerged in 2000 causes severe lesions also in ducks and other waterfowl species.

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13
Q

HPAI clinical signs
- mortality
- progression
- sequelae
- species differences in response

A

— In poultry (chickens and turkeys) high mortality (70% or higher) in a short period.
— Can be a peracute disease (no lesions observed).
— Secondary bacterial infections can be observed in
animals that survive for longer periods of time.
— Pigeons and waterfowl species show different degrees of resistance, however some strains of H5N1 can cause high mortality in wild birds and waterfowl.
— Pigeons can show neurological signs.

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14
Q

LPAIV pathogenesis? what lesions might we see?

A

Replication in the upper respiratory tract and the intestine, mild to moderate lesions:
* Catarrhal to fibrinous sinusitis, rhinitis and
tracheitis.
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Replication in the reproductive tract:
* Egg drop syndrome (especially in turkey layers).
<><>
Conjunctival and IO sinus swelling
<><><><>
LPAIV strains replicate within the epithelium/mucosa of the respiratory, gastrointestinal and reproductive tract.
High morbidity, and low mortality. There can be bacterial secondary infection, and drop in egg production.

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15
Q

pig to poultry influenza transmission?

A

*H3N2 crossed into turkeys from pigs and continues to cause severe irreversible drop in egg production.
*H1N1 was recently reported in breeder turkeys in Canada, US, Chile and France, causing severe drop in egg production.

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16
Q

TESTING ALGORITHM FOR NAI

A

Suspect or presumptive outbreak (e.g., veterinarian observes high mortality, positive test in regional laboratory, positive tests through surveillance laboratories).
> Confirmation by CFIA
> Outbreak is declared
> trade restrictions, depopulation, control zones

17
Q

components of the primary control zone for avian influenza outbreak
what do they mean?

A
  • Infected zone (3 km)
    – A zone or zones established pursuant to the Health of Animals Regulations, which include all the NAI-positive premises. The outer boundary of an Infected Zone is at least 1 km and up to 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. Birds in infected premises are always culled. Birds in the infected zone maybe culled (pre-emptive depopulation) to avoid spread of the virus. All commercial premises in the infected zone are considered to be Infected Place, and are subjected to quarantine. Quarantine is lifted with negative results for AIV after 21 days from depopulation.
    <><><>
  • Restricted zone (3-10 km) —
    – A zone established immediately surrounding the Infected Zone, and measured based on the epidemiology of the disease under consideration in order 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 (> 10 km)
    – The geographic area between the perimeter of the Restricted Zone and the edge of the Primary Control Zone (PCZ).
    <><><><>
    In restricted and security zones different types of travel restrictions are imposed for poultry, poultry products and other materials. Also, in restricted and security zones there is active weekly surveillance of premises to detect any possible spread of the virus.
18
Q

CURRENT HPAI H5N1 OUTBREAK IN CANADA
- what are its origins?

A
  • Currently, worldwide (northern hemisphere most affected) wave of HPAIV H5N1 outbreaks in both wildlife and poultry
  • Reassortment of H5N8 with wild-bird adapted N1 > HPAIV H5N1 adapted to wild birds (fit to circulate in wild bird hosts)
  • Virus present in Europe in fall 2021, and reached North America in January 2022 through Atlantic flyways
    <><><>
    Currently, there is a new epidemic of H5N1 in the northern hemisphere. Long lasting severe outbreak in North America (since early 2022), likely caused by introduction of the virus by migratory birds through flyways across the Atlantic ocean. This new H5N1 (clade 2.3.4.4b) shows high virulence also in wild birds and it is currently circulating in wild bird populations. Wild mammals are also affected, including skunks and foxes.
19
Q

what is unprecedented about the current HPAI H5N1 outbreak in Canada?

A
  • Unprecedented > HPAIV fit to be maintained in wildlife
  • Ability to circulate and cause disease in multiple wild birds (waterfowl [barnacle
    geese, emperor geese], whooping cranes, raptors, among others)
  • Increased ability to be transmitted to wild mammals, such as foxes (kits), skunks,
    minks, bobcats, coyotes, seals
20
Q

control and prevention of avian influenza
- methods
- vaccines

A

Control = Tight biosecurity.
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Vaccination is NOT regularly conducted:
1. The viruses can change rapidly:
* Immunity is specific for hemagglutinin sub-type;
* Remember: Birds are susceptible to 16 subtypes.
2. Difficult to distinguish between vaccinated and infected animals serologically (important for H5 and H7).
3. Stance of vaccination may change in the future
<><><><>
Vaccination in face of an outbreak is possible, in order to limit the spread of the disease.
However, vaccination for H5 / H7 is not commonly carried out in North America and Europe.

21
Q

canadian surveillance plan for NAI
- what are the components?

A

CanNAISS: Canadian Notifiable Avian Influenza Surveillance System:
* Wild bird surveillance (usually from carcasses);
* Passive surveillance in domestic poultry when clinical signs suggestive of notifiable avian influenza are reported;
* Pre-slaughter surveillance in commercial poultry (serology in chickens and turkeys);
* Surveillance at the hatchery.
<><><><>
- joint initiative of government, industry, and Canadian farmers
- designed to meet notifiable avian influenza guidelines from the World Organisation for Animal Health (OIE) and trade requirements from the European Union.
- allows Canadian poultry producers and processors to do business internationally

22
Q

newcastle disease
- what is the agent? what type of virus?
- serotypes?
- how does it get into host cells?
- what determines virulence?

A
  • Avian orthoavulavirus 1 (AOaV-1) was previously known as Avian Paramyxovirus-1 (APMV-1).
  • Several serogroups of avian orthoavulavirus (AOaV -1 to 21) but AOaV-1 is the most important/significant.
  • The Fusion protein (F) is a transmembrane protein that is present on the envelope of NDV.
  • The function of the F protein is very similar to that of the HA protein in AIV: it allows entrance of the virus into the host cells.
  • The basic mechanisms of activation of the F protein determine NDV virulence, just like HA for AIV.
23
Q

viruelnce of NDV strains
- what determines this?
- virulent vs non-virulent strains differences, names

A
  • The F protein needs to be activated (i.e., cleaved) by tissue (host) enzymes for infection to occur. How easily the F protein can be activated in tissues determines the virulence of NDV strains.
    <><><><>
    Virulent strains:
  • F is activated in multiple tissue > systemic replication > severe disease.
  • Velogenic and mesogenic NDV strains have a virulent configuration of the F protein.
    <><>
    Non-virulent strains:
  • F is activated only in the respiratory and intestinal tracts, leading to localized infection.
  • Lentogenic and asymptomatic enteric NDV strains have a non-virulent configuration of the F protein.
24
Q

NDV pathotypes for chickens
- what are they?
- F protein configuration
- characteristics of morbidity, mortality
- reportable?

A

velogenic:
- Virulent configuration of the F protein
- up to 100% morbidity and mortality
- reportable in canada
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Mesogenic
- Virulent configuration of the F protein
- moderate morbidity and mortality, respiratory lesions usually complicated by secondary infections. circulates in cormorants
- not reportable in canada
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Lentogenic
- non-virulent F protein configuration
- minimal resp disease, usually complicated by bacterial pathogens. used as vaccine
- not reportable
<><><><>
asymptomatic enteric
- non-virulent F protein configuration
- no clinical signs or lesions. used as vaccine.
- not reportable

25
Q

pathogenesis of velogenic NDV

A
  • Virus replicates in the lymphoid tissues of multiple organs and
  • the respiratory and nervous system
26
Q

velogenic NDV strains
- divided into what categories? how do they differ?

A
  • Velogenic Viscerotropic NDV (VVNDV);
  • Up to 100% morbidity and mortality;
  • Severe hemorrhagic lesions in the internal organs.
    <><><><>
  • Velogenic Neurotropic NDV (VNNDV):
  • Up to 50 -60% mortality;
  • Mostly respiratory and neurologic signs.
27
Q

velogenic viscerotropic NDV organs affected and lesions

A

Velogenic strains of NDV tend to affect lymphoid organs (such as spleen), and mucosa-associated lymphoid tissue.
That is why we have lesions in the laryngeal tonsils, the conjunctiva, the cecal tonsils, the lymphoid tissue in the proventriculus and throughout the intestine
<><><><>
- Hemorrhagic conjunctivitis
- Severe hemorrhagic tracheitis and laryngitis
- Mottled spleen and splenic necrosis
- Hemorrhages in proventriculus
- Necrosis of cecal tonsils
- Multifocal hemorrhages in intestine

28
Q

Velogenic neurotropic NDV neurological signs

A
  • Torticollis;
    *Opisthotonous;
    *Paresis / Paralysis;
    *Wing droop;
    *Intentional tremors;
    *Lower mortality than VVNDV, can see more respiratory signs.
29
Q

TESTING ALGORITHM FOR NDV

A

Suspect or presumptive outbreak (veterinarian observes high mortality, positive molecular test in regional laboratory)
> Confirmation by CFIA – also CFIA confirms pathotypes
> Outbreak is declared
> Trade restrictions, depopulation, primary control zones
<><><>
similar to notifiable avian influenza

30
Q

ND control and biosecurity
- what is the main goal of biosecurity?
- what is the purpose of vaccination?
- what animals are vaccinated?
- what is the vaccine type and schedule?

A

Biosecurity (main goal):
- To prevent introduction of NDV from wild birds.
<><><><>
Vaccination (remember just one serotype!):
- To limit infection in case of breach in biosecurity (i.e., from wild birds, such
as cormorants or pigeons).
- Layers and breeders are commonly vaccinated (not broilers in Canada).
- Live vaccine (lentogenic) in young birds (2-3 boosters) followed by killed, oil emulsion vaccination prior to entering laying or breeding cycle.
<><><><>
All NDV strains belong to a single serotype, so vaccination is effective in protecting against clinical signs, even with velogenic strains.

31
Q

what birds are most sensitive to NDV, and what birds are the most resistant to infection?

A

Poultry species are most susceptible
NDV strains circulate in wild birds (waterfowl, cormorants) without clinical signs
<><><>
Poultry species (gallinaceous birds) are the most susceptible to infection with strains of Newcastle disease virus.
Waterfowl (especially ducks) and cormorants are very resistant to infection (only immunosuppressed and very young birds may display clinical signs).

32
Q

NDV in pigeons
- can they be infected?
- viral strains?
- how did it emerge?
- where found?
- virulence?
- can they cause disease it poultry?
- signs?

A

Some AOaV-1 strains are well-adapted for pigeons / doves:
* These AOaV-1 strains are NDV strains by all means
* All AOaV-1 strains that affect pigeons are genetically very similar.
* Possibly emerged as result of transmission of NDV strains from chickens to pigeons.
* Seen in Canada in feral and domestic pigeons - both in agricultural settings and in show / racing birds.
<><><><>
- NDV circulating in pigeons are classified within genotype VI. Remember: these strains are NDV strains for all intents and purposes.
- Similar to NDV in cormorant, NDV strains in pigeons have virulent F cleavage site. These strains can infect and cause disease in poultry.
<><><><>
- neurological signs predominate

33
Q

NDV in cormorants
- virulence
- concern for poultry
- primary signs, who is affected?

A
  • NDV strains circulating in cormorants (as in pigeons) have a virulent F cleavage site.
  • This is a concern, as these strains can infect and cause disease in poultry.
  • NDV in cormorants causes neurological disease, mainly in young birds. (encephalitis)

3. Comparative (23 decks)

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