Criteria & Levels

This page provides a complete reference for the 11 evaluation criteria used in this Multi-Criteria Decision Analysis (MCDA) framework for prioritizing pig diseases.

Overview

Each disease is systematically evaluated across 11 standardized criteria. All criteria follow a concern-based framework, where levels progress from least concern to greatest concern. This consistent structure enables meaningful comparisons across diverse disease threats.

Within each criterion, levels are strictly ordered from best outcome (least concern) to worst outcome (greatest concern). In the PAPRIKA elicitation process and in 1000minds software, levels are entered in this exact order to ensure consistent interpretation of trade-off questions.

The 11 Criteria

1. Foodborne Zoonotic Transmission Potential

What it measures: Risk of human infection through consumption of pork products.

Why it matters: Evaluates whether the pathogen can transmit from pigs to humans via the food chain. Relevant control points may include ante- and postmortem slaughter inspection, cross-contamination during processing, and post-processing food handling.

Levels (least → greatest concern):

  1. Highly unlikely: No controls necessary
  2. Rarely occurs: Requires significant failure at one or more control points for transmission to humans
  3. Sometimes occurs: Even minor control point failures likely to result in transmission to humans
  4. Likely to occur: Effective control measures not fully understood

2. Non-Foodborne Zoonotic Transmission Potential

What it measures: Risk of human infection through routes other than food consumption.

Why it matters: Identifies diseases that pose health risks to farm workers, veterinarians, and others who work with pigs, as well as potential public health concerns.

Transmission routes included:

  • Occupational exposure on farms (farmers, veterinarians, technicians)
  • Aerosol transmission from infected pigs or environments
  • Environmental contamination (water, soil)
  • Direct contact with infected pigs or their secretions/excretions
  • Arthropod vectors transmitting from pigs to humans

Critical distinction: Mechanical transfer of pathogens on clothing, equipment, or vehicles is NOT zoonotic transmission. Zoonosis requires actual human infection with clinical or subclinical disease, not passive transport of pathogens between pig populations. A farmworker who carries PEDV on boots to another farm has not experienced zoonotic transmission—the virus did not infect the human.

Levels (least → greatest concern):

  1. Highly unlikely: No evidence of non-foodborne zoonotic transmission
  2. Occupational exposure risk: Non-foodborne transmission pathway(s) that are strongly associated with occupational exposure and can lead to human infection
  3. Public exposure risk: Non-foodborne transmission pathways, beyond occupational exposure, that can lead to human infection

3. Effectiveness of On-Farm Biosecurity in Preventing Farm-to-Farm Transmission

What it measures: The extent to which routine on-farm biosecurity can prevent farm-to-farm transmission.

Key principle: The inherent assumption is that, with rare exceptions, direct pig-to-pig transmission can occur with virtually all diseases. Transportation risk and hygiene are considered part of on-farm biosecurity because producers have substantial control over them. Diseases with wildlife reservoirs or vectors are examples where on-farm biosecurity may not adequately limit farm-to-farm spread.

Pathways INCLUDED in biosecurity assessment:

  • Direct pig-to-pig contact during transport or commingling
  • Trucks and transport vehicles
  • Boots, footwear, clothing
  • Equipment and tools
  • Personnel movement

Pathways that may BYPASS biosecurity:

  • Wildlife reservoirs (wild boar, rodents, birds, etc.)
  • Arthropod vectors (mosquitoes, ticks, flies as biological vectors)
  • Aerosol spread beyond farm boundaries
  • Long-term environmental persistence (soil, water contamination)
  • Contaminated feed or feed ingredients

Levels (least → greatest concern):

  1. Not applicable: Agent is ubiquitous on all or most US farms
  2. Highly effective: Routine on-farm biosecurity measures are effective in preventing farm-to-farm transmission
  3. Moderately effective: Requires high level of compliance with extraordinary on-farm biosecurity measures to prevent farm-to-farm transmission
  4. Unlikely to be effective: One or more pathways of farm-to-farm transmission exist that cannot be controlled by on-farm biosecurity

Example applications:

Scenario Level Assignment
Commensal organism present on virtually all farms (e.g., Strep suis) Not applicable
Disease controlled entirely by managing pig contact and fomites Highly effective
Disease with occasional wildlife spillover but primarily pig-to-pig spread Moderately effective
Disease maintained primarily by wild boar populations or aerosol spread Unlikely to be effective

4. Difficulty of Detecting and Confirming Infection

What it measures: The challenge of recognizing and confirming the disease, combining both clinical recognition and diagnostic capability.

Why it matters: Reflects how quickly and reliably the disease can be identified in the field or with laboratory support, which affects response speed and containment effectiveness.

Key assumption: NVSL and FADDL can essentially test for anything, either with standardized tests or NGS/sequencing; therefore this criterion focuses mainly on what is available at local or regional laboratory level and what can be recognized in routine practice.

Levels (least → greatest concern):

  1. Easy: Distinct clinical signs and/or existing test(s) available at local/regional laboratory(s)
  2. Moderate: Clinical signs not unique but existing tests available at local/regional laboratory(s)
  3. Difficult: Clinical signs not unique and test(s) not available at local/regional laboratory
  4. Very difficult: Clinical signs not unique and reliable test(s) to identify antigen or antibody are not available (rely on NGS or nonspecific tests)

5. Financial Impact on Farm's Cost of Production

What it measures: Direct financial losses from the disease itself, including mortality, morbidity, reduced growth rates, treatment costs, and lost productivity.

Important: This does NOT include market or trade impacts (covered separately in Criterion 6).

Why it matters: Quantifies the on-farm economic burden of disease.

Levels (least → greatest concern):

  1. Negligible: No measurable losses
  2. Minor: Low prevalence, typically non-lethal infection with recovery very likely
  3. Moderate: Manageable losses related to endemic (population) or chronic (individual) occurrence
  4. Substantial: Unsustainable acute or chronic losses related to severe clinical signs in a high prevalence of animals

6. Effect on Domestic or Export Markets

What it measures: Impact on market access, prices, consumer confidence, and trade relationships resulting from disease detection.

Why it matters: Includes export restrictions, domestic movement controls, market closures, price impacts, and regulatory trade responses when disease occurs on one or more farms.

Levels (least → greatest concern):

  1. Negligible: Little or no market disruption when disease occurs on one or more farms
  2. Temporary disruption: Measureable negative effect on demand for less than a month when disease occurs on one or more farms
  3. Significant disruption: Measureable negative effect on demand for 1 to 6 months when disease occurs on one or more farms
  4. Prolonged disruption: Measureable negative effect on demand for more than 6 months when disease occurs on one or more farms

7. Pathogen's Ability to Develop and Spread Resistance

What it measures: The pathogen's biological capacity to acquire, carry, and transmit antimicrobial resistance genes to other bacteria.

Key distinction: This criterion evaluates the organism's inherent biology—its capacity for acquiring and disseminating resistance genes, horizontal gene transfer potential, mutation rates, and fitness costs. This is independent of how the disease is actually managed in the field (that's Criterion 8).

Why it matters: Identifies pathogens that contribute to the broader AMR crisis through horizontal gene transfer.

Levels (least → greatest concern):

  1. Minimal risk: Agent inherently unlikely to develop clinically important resistance to antibacterial or antiviral treatments
  2. Moderate risk: Evidence of development of clinically important resistance to antibacterial or antiviral treatments, or that development of such resistance is likely to occur over time
  3. High risk: Resistance to antibacterial or antiviral treatments is, or can be expected to be a common problem

Note: Viral diseases and parasites generally score "Minimal risk" because they don't carry or transmit antimicrobial resistance genes relevant to bacterial AMR concerns.

8. AMR Development Driven by Disease Management

What it measures: The extent to which controlling or treating this disease drives antimicrobial use in pig populations, creating selection pressure for resistance.

Key distinction: This criterion evaluates drug use patterns—how much antimicrobial use this disease generates in the field. This is independent of the pathogen's own resistance characteristics (that's Criterion 7).

Why it matters: More antimicrobial use creates selection pressure for resistance development across all bacteria on farms, not just the target pathogen.

Levels (least → greatest concern):

  1. Minimal risk: Antibacterial or antiviral treatments rarely occur, or are typically limited to short-course individual animal therapy
  2. Moderate risk: Antibacterial or antiviral treatments are commonly used for treating affected individuals
  3. High risk: Antibacterial or antiviral treatments commonly used on affected groups, or for prophylaxis

Why separate Criteria 7 and 8?

A disease might drive heavy antimicrobial use (high Criterion 8) but be caused by a virus with no AMR risk (low Criterion 7). Conversely, a highly resistant bacterial pathogen (high Criterion 7) might cause disease that is rarely treated (low Criterion 8). Separating these dimensions captures both concerns without conflation.

Example Criterion 7 Criterion 8
Viral respiratory disease with secondary bacterial pneumonia requiring treatment Minimal (virus) Moderate-High (drives antimicrobial use)
Highly resistant bacterium causing rare clinical disease High (biology) Minimal (rarely treated)

9. Availability of Effective Treatment Options

What it measures: The existence and effectiveness of therapeutic interventions that can alter disease outcomes in infected animals.

Why it matters: Considers both availability in the United States and actual efficacy in field conditions.

Levels (least → greatest concern):

  1. Widely available: Multiple effective treatments widely available in the US
  2. Available but with uncertain efficacy: Limited treatments available in US or are only effective in some situations
  3. No availability: Effective treatments not currently available in the US (or have not been developed)

10. Availability of Effective Vaccines or Bacterins

What it measures: The existence and effectiveness of preventive vaccination options.

Why it matters: Considers vaccine efficacy, practical availability in the United States, breadth of protection, and whether vaccines are part of standard disease control programs, including national response stockpiles where relevant.

Levels (least → greatest concern):

  1. Widely available: Effective commercial vaccines widely available in the US (or held in national response stockpile)
  2. Available but uncertain efficacy: Commercial or autogenous vaccines exist in the US but protection may be inconsistent
  3. No availability: Effective vaccines not currently available in the US (or have not been developed)

11. Feasibility of Eradicating the Disease from the US

What it measures: The biological and practical feasibility of completely eliminating the disease from domestic US pig populations using available tools and foreseeable resources.

Why it matters: Considers both technical feasibility and realistic implementation, including logistics, regulation, infrastructure, and producer behaviour. Helps prioritize diseases where eradication is achievable versus those requiring ongoing management.

Levels (least → greatest concern):

  1. Highly likely: Can be eradicated using existing tools and knowledge
  2. Possible: Eradication possible but likely to require major changes into logistic systems, regulatory environment, infrastructure, and producer behaviors
  3. Difficult and uncertain: Extremely difficult and with uncertain success rate, few global examples of success even at farm level
  4. Not feasible: Eradication extremely unlikely
  5. Unknown: Feasibility of eradication not known

Note: The "Unknown" level is reserved for emerging diseases where insufficient field experience precludes confident assessment of eradication potential.

Disease Brief Requirements

All disease briefs must adhere to the following standards to ensure consistency and enable automated processing:

  1. Follow the standard template structure exactly as specified in _template.md

  2. Include the LEVELS line immediately below the disease title, with exactly 11 semicolon-separated values corresponding to the 11 criteria in order

  3. Use level labels exactly as defined in this framework—no paraphrasing, abbreviation, or rewording

  4. Provide justification paragraphs for each criterion explaining the evidence basis for the level assignment

  5. Include an overview paragraph describing the disease, causative agent, and relevance to US pig production

  6. Document uncertainty explicitly when evidence is limited or conflicting, distinguishing established facts from provisional conclusions or theoretical risks

How to Use This Framework

When evaluating a disease:

  1. Read the criterion description to understand what is being measured
  2. Review all level definitions for that criterion before selecting
  3. Consider the guidance notes and example applications where provided
  4. Select the level that best matches the disease characteristics based on available evidence
  5. Document your rationale in the disease brief justification paragraph

All disease assessments should be evidence-based, drawing from peer-reviewed literature, surveillance data, diagnostic laboratory findings, and expert consensus.

Key Principles

  • Concern-based framing: All criteria progress from least concern → greatest concern
  • Consistent application: Level definitions must be applied identically across all diseases
  • Evidence-based: Assessments should be justified with scientific evidence
  • Transparent uncertainty: Limitations in available evidence should be explicitly acknowledged
  • Reproducible: Another assessor reviewing the same evidence should reach similar conclusions