Swine 14 Flashcards

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1
Q

What are major areas of concern for the Canadian swine industry in the event of an outbreak of foreign animal disease?

A

n Economics
> Shut down exports – 50% of production exported
n Restrict farm-to-farm movement
> Multi-site production, pig flow affected
n Disposal of carcasses
n Mental health

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2
Q

What major foreign animal disease(s) is/are the “most likely” to occur in the Canadian pig population?

A
  • pseudorabies
  • foot and mouth disease
  • hog cholera
  • african swine fever
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3
Q

Pseudorabies (Aujeszky’s Disease) is caused by what virus?

A

Pseudorabies virus
> suid herpesvirus 1 (suHV-1)

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4
Q

Pseudorabies (Aujeszky’s Disease) - persists in the host in what state, leading to what?

A
  • can persist in latent state
  • resulting in carrier animals and subclinical infections
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5
Q

Pseudorabies (Aujeszky’s Disease) survival in environment, susceptibility

A

Moderately resistant outside of the host
- Probably doesn’t survive much longer than 2 weeks outside of host
- Can be destroyed by disinfectants

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6
Q

can we distinguish pseudorabies titer from natural infection?

A

Marker vaccines make it possible to distinguish vaccine titres from natural virus antibody levels

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7
Q

Pseudorabies pathogenesis? predilection sites?

A

Pathogenesis: varies depending on the viral strain, age of pig, and viral load
- Inhalation or ingestion
> Replicates in upper respiratory tract epithelium
- Spreads to LN then, CNS: spinal cord and brain
> Localizes in many areas forms intranuclear inclusion bodies
- Localizes in Tonsil primary site
- Causes inflammation and necrosis of tissue
- Respiratory tract, bronchial tree, alveoli, endometritis, vaginitis, necrotic placentitis, fetus
()()()()
epithelial cells of upper resp tract > lymph vessles
> tonsil and local lymph nodes, then possibilities:

  1. > neurons innervating the facial and oropharyngeal area
    -olfactory
    -trigeminal
    -glossopharyngeal
    replication of PRV in the central nervous system is characterized by nonsupprative meningoencephalitis causing severe central nervous disorders
    further spread to different neurons
    latent infectin of neurons
  2. > viremia
    dissemination to multiple organs
    replication in epithelia, vascular endothelium, lymphocytes, and macrophages
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8
Q

what happens when Pseydorabies gets into the central nervous system? what lesions do we see?

A

eplication of PRV in the central nervous system is characterized by nonsupprative meningoencephalitis causing severe central nervous disorders

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9
Q

Pseudorabies (Aujeszky’s Disease) is excreted how? for how long?

A

Excreted in large numbers in saliva, nasal secretions, urine and feces (for up to 2 weeks)

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10
Q

Pseudorabies (Aujeszky’s Disease) persists where in the pig?

A

n Persists in tonsil for several weeks
n Latent in CNS for many months

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11
Q

Pseudorabies (Aujeszky’s Disease): non-swine dead-end hosts; what animals, what signs? what countries

A

– causes fatal neurologic disease (rabies-like signs) and severe itching (mad-itch)
> Dogs, cats, cattle mice, racoons, mink, foxes….
> Found in most countries except: Canada, Greenland, Australia.
> USA – eradicated from commercial herds 2004

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12
Q

Pseudorabies (Aujeszky’s Disease) transmission

A
  • Highly contagious, spreads through herd rapidly
  • Mainly spread through respiratory route, oral-nasal
    > pig-to-pig via oral and nasal secretions
  • Also, transplacental, milk, vaginal mucosa, semen
  • Possibly airborne
  • Fomites
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13
Q

Pseudorabies: clinical signs are variable, what do they depend on?

A
  • Three ‘overlapping’ syndromes
  • Age-dependant
  • Infectious dose and strain dependant
    > CNS, respiratory and reproductive
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14
Q

Pseudorabies: clinical signs in neonates. when do we see them? what are they? what about in weaned pigs?

A

NEONATES:
- Ill within 2-4 days after exposure
> High mortality ~100% usually within 1-3 days
> Sometimes sudden death
- Listless, anorexic, and pyrexia
- Neurological signs
> depression, tremors, convulsions, incoordination, dog-sitting posture, coma and death

Weaned pigs:
- Similar signs but mortality is usually much lower

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15
Q

Pseudorabies: clinical signs in gow-finish pigs:

A
  • Primarily respiratory signs
    > Coughing, sneezing, nasal discharge
    > Loss of body condition
  • Pyrexia, anorexia, depression
  • +/- CNS signs: tremors, convulsions
  • High morbidity and low mortality
    > many recover in 7-10 days
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16
Q

Pseudorabies: clinical signs in adult swine

A
  • Pyrexia, anorexia
  • Respiratory signs
    > sneezing and coughing and laboured breathing
  • Most recover
  • Abortions, returns, stillbirths, weak pigs
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17
Q

Pseudorabies in non-swine species: who is susceptible/ clinical signs?

A
  • Dead-end hosts
    > All livestock mammals, and cats, dogs, raccoons, skunks
  • Infected animals die within 1 to 2 days
    before shedding virus – always fatal
  • Intense pruritis (mad itch)
  • Neurological signs (rabies-like)
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18
Q

psudorabies gross lesions and histology

A

Gross lesions:
- fibrinonecrotic rhinitis / severe necrotizing rhinitis
- necrotic tonsillitis
- foci of necrosis in liver (neonate), spleen, lung
- aborted fetuses
> microscopic lesions in nervous tissue

Histology:
- intranuclear inclusion bodies

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19
Q

Pseudorabies; diagnosis and control

A
  • History: including death of cats and dogs, high mortality in neonates, abortions, neurologic signs
  • Many tests: FA, IHC, PCR, HISTOLOGY
  • Eradication in U.S. (2004)
    > DIVA Vaccine (gene-deleted)
    > Vaccine highly efficacious
  • No treatment
  • Inform CFIA of suspected cases – REPORTABLE!!
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20
Q

Foot-and-mouth disease (FMD); caused by what type of virus? strains?

A
  • Picornaviridae
  • Many strains - differ antigenically, limited cross protection
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21
Q

Foot-and-mouth disease (FMD) transmission

A
  • Transmitted through respiratory droplets and nose-to-nose contact
    > 50km aerosol
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22
Q

Foot-and-mouth disease (FMD) affects what type of animals?

A

Affects most ruminants and pigs (cloven-hooved animals)
- Horses resistant

23
Q

Foot-and-mouth disease (FMD); does it infect many species? how contagious? how well does it survive in the environment?

A

Multi species – HIGHLY contagious. VERY RESISTANT TO DISINFECTANTS, SURVIVES IN ENVIRO FOR LONG TIME

24
Q

Foot-and-mouth disease (FMD) last outbreak in canada? how costly?

A

Last outbreak in Canada: Saskatchewan 1951-1952
>25 farms affectd, 6.6 billion in todays dollars lost

25
Q

Foot-and-mouth disease (FMD); pigs vs ruminants infectious dose for oral route? are pigs susceptible to airborne route?

A

Pigs
- Lower infectious dose for oral route of exposure relative to ruminant
- Relatively resistant to airborne infection

26
Q

how much FMD does an infected pig vs ruminant excrete into the air per day?

A
  • Infectious pig = 400M infectious doses/day
  • Infectious ruminant = 120K infectious doses/day
27
Q

carrier stage of FMD is how long for pigs? (and cattle, small rum)

A

Pigs = 28 days

-Cattle – up to 3.5 years
-Small ruminants up to 9 months

28
Q

FMD incubation

A

n 2-14 days

29
Q

FMD clinical signs in pigs

A
  • Acute lameness - often first sign noticed
    > 1-5 days after infection
  • Pyrexia – slobbering, salivating and chomping
  • Start as small, blanched foci in skin vesicles on lips and tongue, teats, and udder
  • High morbidity, mortality ~5% but higher in younger piglets
30
Q

FMD in piglets: what are the signs?

A
  • Vesicles similar to sows
  • High mortality
  • Vesicles at coronary bands, hooves may fall off
31
Q

what would happen if an FMD outbreak occurred?

A
  • Humane destruction of all infected and exposed animals
  • Tracing to identify locations of potentially infected or exposed animals
  • Quarantine – and restricted movements
  • Zoning to define infected and disease-free areas
32
Q

vesicular diseases

A

-Foot-and-Mouth Disease
-Swine Vesicular Disease
-Seneca Virus A
-Vesicular Stomatitis
-Vesicular Exanthema

33
Q

Changing trends in FAD investigations - why?

A

way more investigations in recent years ~2017 onwards
-FAD confirmed cases increased in 2014, 2015… so investigations increased

34
Q

proportion on foreign animal disease investigations due to vesicular conditions in 2012, and 2018

A

2012: 81%
>mostly equids, then bovids…

2018: 83%
>92% of these due to pigs!

35
Q

hog cholera is caused by what virus? virulence varies how? eradicated where and when?

A

Pestivirus
- Strains vary in virulence
- Eradicated from USA in 1970’s

36
Q

clinical signs of hog cholera

A

Clinical Signs (varies with virulence of virus)
1. Lethargic, depressed, appear chilled
2. High fever, conjunctivitis, +/- constipation
3. Severe watery diarrhea, vomiting
4. Gaunt, weak, posterior paresis, cyanosis
5. Sudden outbreak of high mortality
6. Clinical signs include fever, lethargy, cyanotic extremities

37
Q

hog cholera lesions

A
  • button ulcers in cecum enlarged spleen with infarction of the spleen
  • “turkey egg kidneys”
    > Petchechia (hemorrhages) in kidney and lymph nodes
38
Q

African Swine Fever is what type of virus? transmitted how? is it contagious?

A

n Asfarviridae
n Enveloped DNA virus
n Transmitted by arthropods
n Highly contagious viral disease of swine

39
Q

is ASF virulence always the same?

A

isolates vary in virulence
n High: up to 100% mortality
n Low: seroconversion

40
Q

ASF: how well does it survive in the environment? what is it susceptible to? who does it affect?

A

n Highly resistant
n Killed by high temperatures and
some disinfectants
n Affects domestic and wild pigs
n May be asymptomatic in wild pigs

41
Q

ASF treatment and control

A

No treatment, no vaccine!
- FDA vaccine press release Oct 1, 2021

42
Q

ASF history

A

n Kenya early 1900s
n Spread to Europe
n Vector identified/described 1963
n Emergence in western hemisphere 1971 (Cuba)
n Recent outbreaks:
> Africa, Russia, Western Europe, China 2018, Belgium 2018, Dominical Republic 2021!!

43
Q

ASF Transmission

A
  • Direct contact
    > Usually oronasal secretions
  • Indirect
    > Uncooked garbage, fomites, bite of infected tick, biting insects
  • Is found in all tissues and body fluids
  • Incubation thought to be 5 to 19 days
44
Q

ASF clinical signs of acute disease and incubation

A

Acute disease
- Incubation 5-19 days, but can be < 5 days after exposure to tick
- Pyrexia, anorexia, erythema, cyanosis
- Recumbency
- Bloody diarrhea
- Abortion
- Sudden death

45
Q

ASF clinical signs of chronic disease

A

Chronic disease
n Multi-focal erythema
> Ears, abdomen
> Raised or necrotic areas
n Low fever
n Painless joint swelling
n Emaciation
n Death

46
Q

ASF Post mortem lesions

A

Highly variable lesions but, most common are:
Hemorrhagic
- Spleen
> Enlarged
> Friable
> Dark red, black
- Lymph nodes
- Kidneys
- Heart

47
Q

ASF - Differential Diagnosis

A

n Classical swine fever – clinically indistinguishable
n Acute PRRS
n Porcine Dermatopathy and nephropathy syndrome
n Erysipelas
n Salmonellosis
n Actinobacillosis
n Glasser’s disease
n Pseudorabies
n ………warfarin poisoning, heavy metal toxicosis, thrombocytopenia, generalized septicemic or hemorrhagic conditions

48
Q

do zoonotic swine diseases commonly cause problems in north america?

A

Many POTENTIAL pathogens
- In North America most agents:
> Not present or very rarely cause problems
> However, may be of importance to young children, those with compromised immune systems

49
Q

notable zoonotic diseases of swine

A

Leptospira pomona
Strep. suis type 2
Toxoplasma gondii
Salmonella spp
Others…

50
Q

Leptospira pomona is transmitted to humans how? what would it do to a human? how can we avoid catching this from swine?

A
  • Transmitted by urine and infected water
  • Bacterial contact with mucus membranes, skin, eyes
  • Leptospirosis in human
    – Splenomegaly, hepatitis, nephritis

Recommendations
1. Vaccinate sows against Lepto
2. Use gloves when assisting with dystocia

51
Q

Strep. suis type 2 - is this a common disease in pigs? what can it do to people? how common is it for people and who?

A
  • Widespread among pig population
  • Septicemia, meningitis, balance disorders, hearing loss in people
  • Occupational disease: about 100 cases/yr
  • Low infectivity
  • Most common in abattoir workers and in people in developing countries eating pigs with clinical signs of Strep suis
52
Q

how do people get toxoplasma gondii from swine? is it common in ontario? how to control?

A
  • Infection via undercooked/uncooked meat
  • Cats excrete oocysts in feces
  • Pigs become infected by consuming oocysts
  • Low prevalence in Ontario herds (1%) and Ontario pigs (0.1%)
  • Persist in tissues of pigs for long periods
    – High prevalence in sows in positive herds
  • Control measures - cat & rodent control
53
Q

how to avoid salmonella issues from swine to people

A
  • Food-borne human health risk
  • Farm-to-fork continuum
  • Control at abattoir and in kitchen
  • Improved hygiene and management