Dinámica de infección Cadena de Infección/Cadena de

Prevención PRRS

Eduardo Fano Edgar Díaz Reid Philips

Jean Paul Cano Enrique Mondaca

Boehringer Ingelheim Vetmedica Inc

Enfoque en lechón Enfoque en el sistema

Chain of the infection in the Epidemiology field: Individual (host)approach

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3 Image courtesy of: http://www.cetl.org.uk/learning/img1/chain-infection.jpg

Cadena  de  infección  entre  fases  de  producción  con  enfoque  poblacional  

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PLEASE INSERT Presentation title 5

Sow  Herd

Nursery

Finishing

GDU

Multiplier

"Cadenade  Produccion" "Cadenade  Infeccion" "Cadenade  Prevencion"

Cadena de Producción/Cadena de infección/Cadena de Prevención

Fuente de Primeriza

s

Desarrollo Reemplazo

s Hembras

Parto y lactantes

Destete a finalizado

Venta a mercado

Cadena  de  infección/Prevención    Un  enfoque  sistemá:co      

Enfoque sistematico

Minimizar exposición y Maximizar inmunidad

Minimizar exposición y Maximizar inmunidad

Minimizar exposición y Maximizar inmunidad

Minimizar exposición y Maximizar inmunidad

Manejo de la Transmision

Vertical

TH -------------TH---------------TH--------------TH-------------TH

TV

TH -------------TH---------------TH--------------TH---------------TH

PRRS virus “Infection Chain”

Level 1

Replacement animals

Level 2

Sow herd

Level 3

Wean to finish pigs

Horizontal transmission

Vertical transmission

Horizontal transmission

Lateral

spread

External - Gilts +Gilts

Local Replacement

Fano et al., 2007

Important to understand the PRRSv status and pattern of circulation within herds at each phase of production.

Level 1: Gilt Development

• Goal: Prepare and introduce immune and non-infectious replacement animals to recipient breeding herds

•  Why important? A reason for endemic/chronic PRRSv transmission/infection within a breeding herd is introduction of naïve or actively infected replacement gilts

•  How? •  Appropriate pig-flow w/ AI-AO strategy •  Manage immunity to PRRSv

•  Role of the replacement gilt in the maintenance of the PRRS infectious process; S.A. Dee PhD, Leman Swine Conf., 1998

•  The science of PRRS: What do we really know about its transmission, diagnosis and control?; S.A. Dee PhD, AASV proc., 2004

0 7 37 67 97 127 DPI

Sent 1

MN30100 MLV 1 MLV 2 MLV 3

Sent 2 Sent 3 All + All + NVC + All Vx -

Therapeutic MLV reduced PRRSV shedding to sentinels

Level 2: Sow Herd

• Goal: Attain and maintain stability to PRRSv in positive breeding herds – wean PRRSv negative pigs

•  Definition of stability: No evidence of PRRSv transmission horizontally or vertically •  The science of PRRS: What do we really know about transmission, diagnosis &

control; S.A. Dee PhD, AASV, 2004

•  Must understand the status and pattern of PRRSv circulation within the breeding herd

•  PRRSv status of incoming replacement gilts

•  PRRSv status of piglets at weaning

Achieving Breeding Herd Stability for PRRS

o Ultimate Goal : Wean PRRSv Negative Pigs

o Employ protocols that minimize viral replication and transmission w/in a population of animals

§  Must eliminate subpopulations to attain and maintain uniform immunity within the population §  Detecting subpopulations after PRRSv infection in large breeding herds; S.A.

Dee PhD et.al., SHAP, 1996

o  Employ protocols that generate uniform population immunity – Mass Vaccination

§  Maximize Immunity & Minimize Exposure o  Often employed w/ a form of herd/population closure

§  LOAD – CLOSE- EXPOSE protocol w/ Al-AO farrowing room mgmt §  Quantifying the production impact in farms using load-close-expose

programs for PRRSv; D. Linhares et.al., AASV proc, 2013 §  Time to produce PRRSv-negative pigs from infected breeding sites; D.

Linhares et.al., AASV, 2013 §  McRebel PRRS; MB McCaw, Leman Proc., 1995

Stabilization of PRRS virus infection in breeding herds: research summary

From Daniel Linhares PhD dissertation

Daniel Linhares,1 Jean Paul Cano,2 Montse Torremorell,1 Robert Morrison1

1College of Veterinary Medicine, University of Minnesota 2Boehringer Ingelheim Vetmedica, Inc

0   10   20   30   40   50  

LVI  

MLV  

weeks  

Treatm

ent  

PRRSV  Load-­‐Close-­‐Expose  program  ?meline  

PRRSv-­‐detec:on   LCH   TTBP   TTNP  

PRRS-negative herd?

Dion et al., 2010

Level 3: PRRSv Control in Growing Pigs Wean to finish pigs

• Understand/Confirm prevalence of PRRSv at weaning

• Understand/Confirm pattern of PRRSv transmission/infection in growing pig flow and/or risk of lateral introduction of virus

•  Horizontal and/or Lateral introduction

•  Fundamental for targeting control interventions

Control Group

Vaccine Group

DD

DD

-29 5 0 3 8 36 70 95 118 DPI

Pig arrival Sorting

Weigh ID

1-18-2 challenge

ATP vaccinations

»  Serum and Bioaerosol samples tested by RT-PCR

Slaughter Weigh

Therapeutic MLV reduced PRRSV shedding in OF & air

PRRSV in aerosol CONTROL VACCINATED Mean (RNA copies/mL) 4.3 x 108 a 4.5 x 108 a

range min 1.2x104 4.9x103

range max 1.9x109 2x109

95% conf interval 2.6 x108 - 6.1 x 108 a 2.7 x 108 - 8.1 x 108 a # pos days 31a 17b

last DPI positive 70 45

# pos days (McNemar's test p-value 0.0004)

RNAc/mL in positive days (Wilcoxon p-value 0.1243)

Different superscript represent statistical significance (α = 0.05)

Vertical transmission modulation : multiplier farm

Young Gilt immunization and horizontal transmission manipulation by proper animal flow Re- immunization, Status verification

Massive intervention: immunization

Massive intervention: immunization Status verification

Massive intervention: immunization Pre-farrowing intervention Status verification Vertical transmission modulation : sow herd, In-house processes (cross fostering, environment control, etc)

Piglet immunization Agent spread: Nursery and Finishing

Piglet colonization Exposure level, piglet immune status

Vertical Transmission Sow shedding status, sow immunity status, exposure level. etc

Sow herd infection pressure Shedding, exposure, immunity, etc

Gilts-P1 and P2+ interaction

I Horizontal transmission

Gilts Introduction Final status?, Naïve or Shedder?, Promoting Sow herd instability?

Gilts development (100 to 200 days old) Naïve?, Shedding? Recovery? , Acclimatization method

Gilts (21 to 100 days old) Onset , Severity and Duration of the infection, shedding status

“Infection Chain™ ”: Understanding Epidemiological events… then.. “Prevention Chain™”

Conclusions

•  Minimizing Exposure –  Gilt Management –  Sow herd stability –  Pig flow –  Immunity

•  Maximizing Immunity –  Vaccination at levels or phases of production

to mitigate the biologic and economic impact of PRRSv

5-Steps PRRS Control Program: A Systematic Approach

1.  Identify Desired Goals

2.  Determine Current PRRS Status

3.  Understand Current Constraints

4.  Develop Solution Options

5.  Implement and Monitor Preferred Solution

Systematic (individual) approach and Regional approach

“The perfect strategy”

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Sow  Herd

Nursery

Finishing

GDU

Multiplier

Production   Chain "Infection Chain" "Prevention Chain"