Table 7 Description of input parameters for individual tree nodes, including their sources and explanations used in the model to assess the pig disease surveillance system through which PRRS is diagnosed in England
Input parameter (including abbreviations) | Value | Source and explanation |
|---|---|---|
Between herd prevalence P*H | 0.351 | Cross-sectional study |
Risk category nodes | ||
Proportion of farms in high pig density area –HDA | 0.284 | [55] |
Proportion of farms using live vaccine- LVAC | RiskBeta(53,96) | Cross-sectional study |
Detection category nodes | ||
Proportion of farms vaccinating –VAC | RiskBeta(64,85) | Cross-sectional study |
Proportion of breeding farms –B | 0.40 | [56] |
Detection nodes: | ||
1. Probability that infected pig shows clinical signs | ||
PRRS vaccinated breeding farms – VACB | RiskBeta(36,29) | Cross-sectional study |
PRRS vaccinated finishing farms-VACF | RiskBeta(36,29) | Cross-sectional study |
PRRS non-vaccinated breeding farms-NVACB | RiskBeta(23,63) | Cross-sectional study |
PRRS non-vaccinated finishing farms-NVACF | RiskBeta(23,63) | Cross-sectional study |
2. Probability that farmer recognize signs and calls vet | ||
PRRS vaccinated breeding farms-VACB | RiskPert(0.4,0.5,0.6) | Medium probability [57]: less severe clinical signs were expected due to vaccination which could go unnoticed compare to non-vaccinated farms |
PRRS vaccinated finishing farms-VACF | RiskPert(0.1,0.2,0.3) | Low probability [57]: it was believed that clinical signs seen in this type of farms are more difficult to recognize compare to breeding farms plus the effect of vaccination resulted in low probability |
PRRS non-vaccinated breeding farms-NVACB | RiskPert(0.7,0.8,0.9) | High probability [57]: non vaccinated farms are likely to have more naïve population therefore clinical manifestation would be more apparent |
PRRS non-vaccinated finishing farms-NVACF | RiskPert(0.4,0.5,0.6) | Medium probability [57]: similar to non-vaccinated breeding farms but clinical signs slightly less severe |
3. Probability that vet collects the sample | Â | Â |
PRRS vaccinated breeding farms-VACB | RiskPert(0.4,0.5,0.6) | Medium probability [57]: based on the same assumption as above |
PRRS vaccinated finishing farms-VACF | RiskPert(0.1,0.2,0.3) | Low probability [57]: based on similar assumption as above |
PRRS non-vaccinated breeding farms-NVACB | RiskPert(0.7,0.8,0.9) | High probability [57]: based on similar assumption as above |
PRRS non-vaccinated finishing farms-NVACF | RiskPert(0.4,0.5,0.6) | Medium probability [57]: based on similar assumption as above |
4. Probability that infected animal test positive | Â | Â |
Sensitivity of PCR test | RiskUniform(0.967,0.999) | Evaluation of the AnDiaTec AcuPig PRRSV real time RT-PCR for the detection of NA and EU strains (www.andiatec.com) |
Sensitivity of ELISA test | RiskUniform(0.961,0.978) | [58] |