Porcine Reproductive and Respiratory Syndrome (PRRS) Flashcards Preview

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Flashcards in Porcine Reproductive and Respiratory Syndrome (PRRS) Deck (30):
1

What causes PRRS?

an arteriveridae?

2

What are the clinical properties of arteriveridae?

1. can cause asymptomatic persistent infections
2. can cause severe fatal dz
3. replicate in macrophages
4. MUTATES

3

What are PRRS virus preferred macrophages to infect?

those in the lung and maternal fetal interface

4

What are the features of PRRSV?ble

1. unstable
2. strain variation
3. variation in virulence

5

What are the major subtypes of PRRSV?

Type 1
Type 2
High path PRRSV

6

What is the epidemiology of PRRS?

1. highly infectious
2. not highly contagious
3. persistent (>100d carrier state)
4. not fully cross-protective across stains
5. subclinical endemic infection common (low virluence in w. canada)

7

How is environmental survival of PRRSV?

1. poor off host
2. susceptible to drying, disinfection etc

8

How is PRRSV transmitted?

1. vertical (semen, transplacental)
2. horizontal (pig to pig, dam to piglet)
3. fomites
4. aerosol--prevalent in hog dense regions

9

What is the pathogenesis of PRRS?

1. replication in lymphoid tissues
2. prolonged viremia--->persistent infection
3. predelication for pulmonary alveolar macrophages and pulmonary intravascular macrophages
4. intersitial pneumoniae
5. cross placenta in late gestation (>d 70). fetal death

10

What are the clinical reproductive signs of PRRS

1. In the pregnant sows can have anorexia, fever, mortality if virulent but more often SUBCLINICAL early farrowing

11

What are the features of the piglets that are born in premature farrowings due to PRRS?

1. weak, liveborn
2. persistently viremic
3. neonatal scours (nonresponsive to antimicobials)
4. elevated preweaning portality

12

What are the respiratory clinical signs of PRRS?

1. dypsnea (thumping)
2. cyanosis of extremities
3. minimal coughing if pure PRRS
4. immunosuppression

13

What are the clinical signs of high fever disease (high path PRRS)

1. high fever
2. blotchy congestion skin
3. abortions
4. high case fatality rate

14

What is the pathology of high fever disease (high path PRRS)

wide spread hemorrhages and edema, diffuse petechiation, splenic infarcts mixed infections

15

What is the etiology of high fever disease?

high path PRRSV

16

What is the pathology of PRRS?

1. non-suppurative interstitial pneumonia
2. systemic vasculitis
3. lymphadenopathy

17

How is PRRS diagnosed?

IHC--antigen
PCR
sequencing/RFLP
Antibodies

18

What is the timeline of antibody response to PRRS?

1. IgM positive 5-14d (recent infection)
2. IgG positive 10-14d (exposure last 1-2 mo)
3. SN serum neutralization--positive within 28d (correlated with clearance

19

What does serum neutralization detect?

neutralizing antibody
correlated with viral clearance but not required for protection

20

How can you monitor for PRRS?

1. oral fluids
2. Studs: ELISA serology, PRRS PCR on semen or blood

21

How is PRRS treated and controlled?

1. treat affected individuals (anti-inflam, secondary infection)
2. vaccination

22

What vaccines should be used for PRRS?

1. attenuated live
(NOT killed)
3 types
prior to breeding/during lactation, in progeny 3-6wk

23

Who are the PRRS vaccinations NOT licenced for?

boars or pregnant sow

24

How is herd elimination of PRRS performed?

1. mass immunization or mass eposure--sterilizing immunity and cessation of ongoing vertical transmission
=breeding herd stablization
*using homologous strain to that present on farm

25

What is serum innoculation (PRRSV)

it is a high risk procedure that involves inoculating the breeding herd with live VIRULENT PRRS

26

What are the steps of serum inoculation (herd elimination of PRRSV)

1. remove NGF population
2. load and close herd
3. expose animals
4. impliment McRebel
5. test pigs at weaning (PCR)
5. restock NGF when consistently negative
6. sentinel gilts
7. open herd

27

What is McRebel?

good managemnet procedures:
max passive immunity
euthanize fall behinds
don't move piglets between rooms
euthanaize pigs that are very sick
dn;t feed back repro tissue to sows before farrowing
all in all out

28

What is the issue with regonal control of PRRSV?

it is not easily kept out of non-infected farms

29

How do you prevent PRRSV entry onto naive farms?

1. live animal quarantine and test
2. test semen
3. transport and wash protocols
4. wash fomites
5. no use of MLV vaccine
6. farm location
7. visitation
8. air filtration! (esp hog dense area)

30

What is an issue with regional elimination of PRRS?

if it gets into the farm then it causes a disaster