Evaluating the effectiveness & costs of strategies post-eradication to monitor for freedom from BVDV infection in Ireland

In Ireland, a national Bovine Viral Diarrhoea (BVD) eradication programme has been effective in reducing national prevalence and has recently been approved by the European Commission. In anticipation of achieving freedom, there is an ongoing discussion regarding appropriate strategies post-eradication to monitor for continued freedom from Bovine Viral Diarrhoea Virus (BVDV) infection of the national cattle sector. The objective of this study is to evaluate the trade-off between the performance of different testing protocols and their associated costs in monitoring BVDV post-eradication in the national cattle sector. By assessing various testing strategies, including bulk tank milk (BTM) testing, first lactation check tests (FLCT), abattoir tests, and youngstock check test (YSCT), the aim is to provide informed input for implementing a long-term sustainable monitoring strategy. In this study, we apply alternative testing protocols to a modelled cattle population in County Kerry, a region with a bovine population considered to be representative of the entire Irish population. The analysis incorporates combinations of Bulk Tank Milk (BTM) testing First Lactation Check tests (FLCT), abattoir tests, and Young Stock Check Testing (YSCT). The YSCT, which focuses on high-risk herds by collecting blood samples from young, homebred animals between nine and 18 months of age, was a key component of the analysis. All tested protocols are capable of timely detection of a BVDV outbreak, with detection times of less than one year. Our results highlight the impact of reducing herd coverage by YSCT on post-eradication surveillance for BVDV freedom. By evaluating the trade-off between increased costs and shortened time to detection, this study provides valuable insights for selecting an appropriate monitoring policy in post-eradication programmes. The findings of this study offer guidance on balancing costs and detection efficiency in monitoring BVDV post-eradication. Understanding the implications of different testing strategies can aid policymakers in making informed decisions to ensure the continued freedom from BVDV in the national cattle sector. All tested protocols are capable of detecting a BVDV outbreak in a timely manner, with detection times of less than one year. However, our results quantify the impact reducing herd coverage by YSCT within a possible post-eradication surveillance programme for BVDV freedom. We evaluate how more herds covered by young stock sampling shorten the time to detection, but at an increased cost. The trade-off between increase in costs per shortened time to detection provides guidance to choose an adequate policy to implement monitoring of disease freedom in national post-eradication programmes. • Employed an individual-based full system model of County Kerry's bovine population • Evaluated costs and effectiveness of alternative BVD surveillance options • Recommendations for sustainable monitoring strategies post-BVD eradication.