Infectious Laryngotracheitis Control Successes Failures Prayers Strategies

D l P lt C f

Successes Failures Prayers Strategies

Delmarva Poultry Conference

September 26, 2012p ,

David Shapiro, DVM, Dipl. ACPVDirector of Veterinary ServicesDirector of Veterinary Services

Perdue Farms, Inc.Salisbury, Maryland, USA

h 410 543 3921phone: 410-543-3921email: david.shapiro@perdue.com

Infectious Laryngotracheitis

•Sporadic but persistent incidence in the United States with Delmarva being the most faithfulStates with Delmarva being the most faithful reservoir.

•Flock supervisors may tell you that I don’t have one, but if I did, I would sell my soul for the ‘good old days’ of LT cycles every 4 5 years!days’ of LT cycles every 4-5 years!

•Sadly but not surprisingly lack of change in LTSadly, but not surprisingly, lack of change in LT prevention strategies has resulted in little change in the LT incidence.

“Those who cannot remember the pastpare condemned to repeat it.”

-George Santayana, 1905

Usually, this phrase is meant to admonish those who foolishly ignore the history of things.

In the case of LT, we are keeping track of almost every f , p g f yconceivable variable and we still can’t figure it out!

We (anyone in favor of poultry health) should be entirelyWe (anyone in favor of poultry health) should be entirely dissatisfied with our results.

Why the Failure?•Lack of concerted effort? Maybe but even those states with a coordinated•Lack of concerted effort? Maybe, but even those states with a coordinated central effort have failed.

•The ILT virus is invincible? Certainly tougher than average but no more y g gformidable than the Marek’s Disease virus or Gumboro virus.

•Difficult to detect? Nope.

•Latency? Perhaps, but hard to blame virus latency when we’re slopping CEO vaccine all over.

•No good vaccines? Admittedly, the efficacy/safety profiles of the currently available vaccines are not as good as those for other diseases.

•Livehaul? Has got to be part of it. We don’t hesitate to haul infected and vaccinated (often almost the same thing) flocks down the road.

•Regulatory dilemma and Vaccinal LT? Certainly prevents us from dealing•Regulatory dilemma and Vaccinal LT? Certainly prevents us from dealing with the problem as openly as we should.

AEGRESCIT MEDENDO• The cure is worse than the diseaseThe cure is worse than the disease.

• Vaccinal LT: Now I can’t remember if I have ever seen a case of “real” LT!

• CEO MLV given by drinking water works to control severe clinical LT but maintains the reservoirCEO MLV given by drinking water works to control severe clinical LT but maintains the reservoir of infection. Post-vaccination reactions are a major problem.

• Spraying CEO MLV doesn’t work well enough.

• Neither does TCO vaccine.

• Recombinant FPvILT vaccines are safe but lack efficacy when used alone.

• Recombinant HVTvILT vaccines work reasonably well and offer a tremendous potential for some degree of eradication but cost, lack of coordination, and export requirements have hindered successful implementation in broilers.

• The usual approach has been to vaccinate with CEO MLV in a limited area and hope the LT doesn’t spread, make a half-hearted attempt at biosecurity and blame other companies for using or not using the correct or incorrect vaccines in the right or wrong areas too early or too late! Really not a great strategy but works just often enough that we keepearly or too late! Really not a great strategy but works just often enough that we keep trying it. It just prolongs the agony.

Is “Vaccinal LT” a scientifically developed designation orIs Vaccinal LT a scientifically developed designation oris vaccine-induced really export-induced?

LT TRANSMISSION•The “Walk-In” (first cases seen near entry door) or “Blow-In” ( y )(first cases near inlets) scenarios as outlined by Dr. Ritter (2007) are real and certainly the most common routes of transmission for Vaccinal LTtransmission for Vaccinal LT.

•They also outline the key biosecurity failings: Walk-In cases demonstrate failure of grower and vendors to use farm-specific biosecurity. Blow-In cases are made possible through widespread CEO MLV vaccination, increased by the regular p , y gmovement of vaccinated and clinical LT flocks to slaughter, and exacerbated by density.

•I would add Stayed-in for the situations where a farm had a break or was CEO vaccinated and then placed the next

i d fl k f h l i h li l ff lunvaccinated flock after a short layout with little effort to clean or heat. This is also essentially a biosecurity failing.

LT DIAGNOSTICS AND SCIENCE

•Rapid PCR diagnostics and histopathology are great but we have found that a water meter and experienced serviceperson are almost as good.

•Serology can be an adjunct to evaluating vaccination and estimating overall incidence but is not an essential tool.

•Molecular biology is really cool but there is definitely a diminishing return. We might be better served by research on psychological strategies designed to convince growers to practice better biosecurity or to

t ffi i l t l t l i l i t/ tencourage government officials to promulgate more logical import/export regulations.

•Research on latency is useful if it is done with the objective of finding a•Research on latency is useful if it is done with the objective of finding a way to convert a latently infected house to a non-infected house.

LT STRATEGY

•Vaccination: Use recombinant vaccines as the primary tool with CEO vaccines as a backup when LT breaks are overwhelming the planoverwhelming the plan.

•Biosecurity: Serious effort to reduce spread from farms that break as well as segregation of the CEO vaccinated and non-vaccinated populations.

•Surveillance: Open communication and reporting of breaks, use of CEO vaccines, and livehaul.

•Between Flock Interventions: Layout, C&D, heating, windrowing, ventilation.

VACCINATIONVACCINATION

From “ILT VACCINATION: RESEARCH AND FIELD EXPERIENCESMark Burleson, DVM, Wayne FarmsDPI 47th National Meeting on Poultry Health and Processing, 2012

From “ILT VACCINATION: RESEARCH AND FIELD EXPERIENCESMark Burleson, DVM, Wayne FarmsDPI 47th National Meeting on Poultry Health and Processing, 2012

From “ILT VACCINATION: RESEARCH AND FIELD EXPERIENCESFrom ILT VACCINATION: RESEARCH AND FIELD EXPERIENCESMark Burleson, DVM, Wayne FarmsDPI 47th National Meeting on Poultry Health and Processing, 2012

Vaccine Cost/BenefitWork out the numbers for yourself. Depending on the situation, eitherlive or recombinant may be the best choice

CEO VACCINE HVTvILT VACCINEcost per bird: $0.0517 $0.0302

live or recombinant may be the best choice.

cost per house/farm: $1,292.50 $755.56

number of birds per house/farm: 25000 25,000 25,000

cost/K doses CEO vaccine: $2.38 $0.0024

hours to CEO vaccinate a house/farm: 2

hourly cost of vaccinator: $15 00 $0 0012hourly cost of vaccinator: $15.00 $0.0012

cost/K doses HVTvILT: $29.75 $0.0302

HVTvILT dilution 1 to X: 1

cost/K chicks HVT: $2.55

other vaccine (e.g. SB1) cost increase/K chicks due to HVTvILT: $0.00 $0.0000

hatchability of vaccinates: 90%

average FC: 2.00

average target weight: 8.00

ton feed cost: $500

CEO FC lost: 0.02 $0.0400

CEO % livability lost: 0.00% $0.0000

CEO % Condemnations Increase 0.20% $0.0080

Increased % flocks treated due to Vx reaction 1.00% $0.0001

Assumptions:*all vaccines 100% field efficacyall vaccines 100% field efficacy

*only recombinant downside is cost

*hatchability should take into account vaccine saver/egg remover

*2% mortality results in 1% lost pounds to plant

*Tx means 2 days Tx at 40 days

BIOSECURITYBIOSECURITY

SURVEILLANCESURVEILLANCE

COMMUNICATIONS

•Notification of breaks is generally good

•Notification of vaccination programs is fair

I t f d/ di t i•Interference and/or disagreement among companies with regard to ILT programs can be an issue; with or without state involvementwithout state involvement.

•Also, try this: Every time you have a break, assign it , y y y , gto either the Blew In, Walked In, or Stayed In causes. Find your weak links.

BETWEENW NFLOCKSFLOCKS

LT STRATEGYHOW WE’RE DOING NOW (USA)

•Vaccination: Use recombinant vaccines as the primary tool with CEO vaccines as a backup when LT breaks are overwhelming the plan. B-

•Biosecurity: Serious effort to reduce spread from farms that break as well as segregation of the CEO vaccinated and non-vaccinated populations. C-populations. C

•Surveillance: Open communication and reporting of breaks, use of CEO vaccines, and livehaul. A-

•Between Flock Interventions: Layout, C&D, heating, windrowing, ventilation. C-

As things stand now, we might graduate but we’re not going to get into a very good schoolinto a very good school.

Our shortfalls are probably based more on behavior than science.

THE ENDTHE END