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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

From: Risk factors for porcine reproductive and respiratory syndrome virus infection and resulting challenges for effective disease surveillance

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   
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   
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]