Modeling the transboundary survival of foreign animal disease pathogens in contaminated feed ingredientsScott Dee DVM MS PhD Dipl;ACVMDirector, Pipestone Applied Research

Introduction1. This is a model involving surrogate viruses when needed.

2. Surrogate selection is based on structural relationships of viruses and the availability of validated diagnostics.

3. Studies are funded by SHIC, AASV, Kemin & KSU.

4. Goal: Evaluate virus survival in feed ingredients under conditions simulating importation to the US from China.

Q 1: Why is this work justified?

Cost of Actual Outbreaks1. CSF in Netherlands (Stegeman et al, 2000)

1. 700,000 pigs slaughtered from infected farms2. 1.1 M pigs killed for pre-emptive reasons

2. FMD in UK (Thompson et al, 2001)3. 7 M animals killed4. Cost = 11.9-18.4 B US $

3. FMD annual global impact (Knight-Jones & Rushton 2013)

1. Endemic areas: 6.5-21 B US $2. Epidemics: >1.5 B US $

4. PED in US (Jung & Saif 2015)1. 7 M pigs died (10% of national pig crop)

Justified, cont.US $ annual estimates (across all commodities)

1. Carpenter et al, 20111. FMD: 2.3-69 B

2. Hayes, 20111. FMD: 12.9 B2. CSF: 9.6 B3. ASF: 16.5 B

3. Paarlberg et al, 2002 & 20091. CSF: 2.6-4.1 B2. FMD: 14 B

Q 2: How do the raw materials become contaminated?

Courtesy, Dr. Pitcher

Contamination, cont.

Contamination, cont.

Courtesy, Drs. Spronk & Schmitt

Project 1: PEDV (Dee et al, BMC Vet Res 2016)

1. Using a transboundary model, PEDV survived in a subset of feed ingredients during a simulated shipment from China into the US.

Soybean meal (Conventional & organic)Lysine, Choline & Vitamin D

2. Mitigants (SalCURB or MCFA blend) were equally effective.

Project 2: FAD SurrogatesObjective: Evaluate trans-Pacific survival of FADs through the use of surrogate viruses, select feed ingredients and the transboundary model.

Hypothesis: Survival will depend on the correct combination of pathogen and ingredient.

FAD* (Surrogate)1. Foot & Mouth Disease Virus (Seneca Valley Virus)

2.Classical Swine Fever Virus (Bovine Virus Diarrhea Virus)

3.Pseudorabies Virus (Bovine HerpesVirus-1)

4.Vesicular Exanthema of Swine Virus (Feline Calici Virus)

5. Nipah Virus (Canine Distemper Virus)

6. Swine Vesicular Disease Virus (Porcine Enterovirus)

7. Vesicular Stomatitis Virus

8. Circovirus

9. PRRS Virus (174)

10. African Swine Fever Virus

* = SHIC swine disease matrix project

Methods1. Ingredients

US Govt Harmonized Tariff ScheduleStandard quantities: ingredient (5g) & virus (10*5 TCID50)

2. Environmental chamber Historical Temperature & % Relative Humidity data

3. Timetable: 37 day trial period (SeaRates.com)

4. Sampling points (4 batches)Day 1 PI: BeijingDay 8 PI: ShanghaiDay 25 PI: San FranciscoDay 37 PI: Des Moines

5. Multiple metrics: PCR/VI/bioassay

Ingredients imported: China to San Francisco*

Ingredient 2012 (lbs) 2013 (lbs) 2014 (lbs)

Soy oil cake 33,278,625 17,550,632 29,800,936

DDGS 8,817,600 5,808,000 6,177,600

Moist pet food 6,908,968 9,062,416 297,352

Soybean meal 40,316,342 39,954,420 2,948,594

Dry pet food 20,568,086 58,449,468 13,424,796

Pork sausage casings 284,603 477,059 10,063,394

Lysine 72,600 209,000 434,808

Choline 41,800 880 0

Vitamin D 56,200 46,200 30,800

Total 55,549,839 34,838,379 41,379,965

* US Govt. Harmonized Tariff schedule

Relationship of route and sampling points

Batch 1 (d 1 PI)

Batch 2 (d 8 PI)Batch 3 (d 25 PI)

Batch 4 (d 37 PI)

Thoughts at this time…. 1. Surrogate viruses representing FAD pathogens demonstrated varying degrees of survival in contaminated feed ingredients during a simulated journey from China to the US.

2. Soy products were supportive matrices for 3 of the 4 surrogates & PEDV.

3. Survival appears to be influenced by viral morphology and ingredient.

4. All 5 stock virus controls were non-viable at day 37 PI, suggesting that a protective feed matrix is essential for survival.

Next steps Phase 2 (underway):

◦ 1. Nipah virus (canine distemper virus)◦ 2. PRRSV◦ 3. Vesicular Stomatitis Virus

◦ As all are enveloped viruses, survival appears limited at this time.

Phase 3 (forthcoming): ◦ PCV2

◦ Swine Vesicular Disease Virus (porcine enterovirus)

◦ ASFV

Phase 4 (mitigation): SalCURB, MCFA blend, Other

Discussion 1. Impact:

◦ These are the first objective data providing proof of concept that feed ingredients could serve as vehicles for FAD entry into North America.

2. Outcomes:◦ 1. Raise awareness of risk.◦ 2. Identification of “high risk combinations” of virus + ingredients.◦ 3. Validation of potential mitigation strategies.

3. Next steps: ◦ This study must affect significant change to protect the North American

industry:◦ Mandatory treatment of high risk ingredients.◦ Ingredient sourcing decisions based on health status, not price.