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Pathways assessment:
Entry Assessment for Exotic Viral
Pathogens of Swine
Lisa A. Ferguson
USDA, APHIS, Veterinary Services
NIAA, Omaha April 2014
Objectives
• Identify and describe pathways by which
exotic viral pathogens of swine may enter the
US
• Estimate the likelihood that each identified
pathway may introduce exotic viral pathogens
of swine into the US
NO
Virus in
region
YES
no
Infected or
contaminated
NO
no
product selected
for export
YES
Virus survives
process prior to
export
YES
NO
Virus survives
transport to
US
YES
Product
contaminated
post-process
NO
Virus survives
import
mitigation at
border
YES
no
no
NO
no
ENTRY
Next steps
• Pathways with non-negligible likelihood of
introduction - estimate likelihood of exposure
• Pathways with non-negligible likelihood of
exposure – evaluate consequences
• Pathways where consequences, overall risk of
introduction, and overall risk of exposure are
non-negligible – identify potential mitigation
measures
Risk estimation terms
Term
Definition
Negligible
So rare that it doesn’t merit consideration
Low
Rare but does occur
Medium
Occurs regularly
High
Occurs very often
Assumptions
• One or more exotic viral pathogens are
present
• Infected animals are selected for slaughter
and/or rendering
• Current regulations and mitigation procedures
effectively enforced
Representative viruses
• Stand in for both single- and double-stranded
RNA and DNA virus
• Encompass a range of resistance to
inactivation
– Classical swine fever
– Foot and mouth disease
– Pseudorabies
Pathway groups
• Airborne
• Inanimate articles serve as fomites
–
–
–
–
–
Animal tissues or fluid and their products
Conveyances and containers
Equipments
Food and feed
Garbage
• Live animals that may serve as vectors or fomites
–
–
–
–
Livestock/germplasm
Humans
Microorganisms or arthropod vectors
Other live animals
Feed ingredient origin
• Animal (rendered products, marine, dairy, etc..)
• Plant (forage, grain, by-products, fats/oils,
vitamins, etc…)
• Microbial culture (amino acids, minerals,
vitamins, etc…)
• Mined material (anticaking, colorants, minerals)
• Synthetic (amino acids, antioxidants, flavors,
minerals, vitamins, etc…)
Rendered animal proteins and fats,
marine by-products
• Includes blood products – none imported
• Rendering process inactivates viruses
• Post-processing contamination unlikely;
transport times and conditions not conducive
to virus survival
• Negligible risk of entry
Milk and milk derivatives
• Small amount of imports
• Treatment sufficient to inactivate FMD
• Post-processing contamination unlikely;
transport times and conditions not conducive
to virus survival
• Negligible risk of entry
Animal manure
• Virus could be present
• Not allowed entry for purpose of feeding
• Negligible risk of entry
Plants and plant products
• Imports – Canada, Argentina, Mexico
• Potential for contamination if contact with
infected animals/excretions/fomites
• ? Virus survival time
• Negligible risk of entry if pelleted/treated;
low risk of entry if unprocessed
Microbial culture
• Amino acids (L-carnitine, lysine, etc..), probiotics,
enzymes (phytase), vitamin (B2, B12), etc.
• Contamination of culture (bacteria, fungi,
bacteriophages) considered production failure;
GMP control
• Recovery of product – sterilization,
centrifugation, filtration, crystallization, etc… not conducive to virus survival
• Negligible risk of entry
Chemical synthesis/mining
• Amino acid (methionine), minerals, vitamins
(A, B1, B3 or B5, B6, B7, B9, D, K; choline), etc..
• Viruses can’t propagate without living animal
cells; contamination unlikely to survive
manufacturing process
• Post-processing contamination unlikely;
transport times and conditions not conducive
to virus survival
• Negligible risk of entry
• Questions?