Challenges to regional PRRS projects

Scott Dee DVM MS PhD Dipl; ACVM

Director of Research

Pipestone Veterinary Clinic

“High PRRS Season”• 2011

– Tough times..• Many filter farm challenges

• Regional project setbacks

– Is this the “New Normal”?

• 2012– The “New Normal” indeed!

• Filters did well

• Infection of non-filtered farms in “isolated regions”

• More challenges for Regional projects

What’s going on and what can we do?

What’s going on: The PRRSV airborne risk is increasing

• The virus is developing ways to challenge classical airborne biosecurity measures such as farm location & filtration.– The frequency, dose and diversity of PRRSV airborne

challenge is very high around farms.• Frequency:

– Elevated number of PRRSV air days

• Dose: – Increased quantity of virus in aerosols

• Diversity: – Multiple variants detected in the surrounding airspace

What can we do?3 options

• 1. Collaboration

• 2. Filtration

• 3. Vaccination

1. Collaboration• Do we need a change of mindset ?

– “Control” versus “elimination”• Risk management & survival mode

– “Vaccinated negative” herd classification• Status of the present (future?)

• We must continue to:• Communicate

– Share outbreak data.

• Map– A picture is worth…..

• Monitor– Keep testing!

• Sequence– Can we do it faster?

2. Air filtration

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Time pre and post air filtration (months)

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New PRRSV infection

Dee et al., Viruses 2012

Limitations

• Filter systems are dynamic entities that change over time.– They age quickly!– The attic environment is not “filter-friendly”..

• Causes breakdown of materials– Impacts filter durability/lifespan– Produces air leaks

• Aerosol challenge vs. filter capacity.– As PRRSV changes, the aerosol challenge dose

increases.• Filters can be overwhelmed if challenge is significant.

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Historical

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Additional details: Accessory components of the filter system

• 1. Boxes

– Don’t bet on the spray foam in the red can…

• 2. Clips

– Have you checked your numbers?

• 3. Insulation

– Pile it on!

• 4. Pre-filter

– Underrated effect…

3. Vaccination

• MLV vaccination

– Therapeutic vs. prophylactic use (BI)

• Improves pig performance

• Reduces virus shedding in exhaust air

Bottom line: Protect yourself and your neighbor!

In addition….

• 1. Don’t overlook the other known risk factors:– Genetics: Infections in remote locations!

– Trucks: Snowball season!

– Slurry: Mechanical and aerosol risk!

• 2. Maintain constant oversight– Personnel compliance

– Daily filter system checks

– Regular biosecurity audits

Conclusions

• 1. The airborne risk of PRRSV continues to increase.

• 2. Regional programs are at a cross-roads.

• 3. Collaboration is more important than ever.

• 4. Take advantage of any/all tools that are available.

• 5. Support the VDL.

• As the virus changes, so must we!