The Irish Programme to Eradicate Bovine Viral Diarrhoea Virus—Organization, Challenges, and Progress

Abstract

A mandatory national Irish bovine viral diarrhoea (BVD) eradication programme, coordinated by Animal Health Ireland, commenced in 2013. Key decisions and programme review are undertaken by a cross-industry Implementation Group (BVDIG) supported by a Technical Working Group. Ear notch tissue is collected from all new-born calves using modified official identity tags, supplemented by additional blood sampling, including for confirmatory testing of calves with initial positive results and testing of their dams. Testing is delivered by private laboratories in conjunction with the National Reference Laboratory, with all results reported to a central database. This database manages key elements of the programme, issuing results to herdowners by short message service messaging supplemented by letters; assigning and exchanging animal-level statuses with government databases of the Department of Agriculture, Food and the Marine to enable legislated restrictions on animal movements; assigning negative herd status based on test results; generating regular reports for programme management and evaluation and providing herd-specific dashboards for a range of users. Legislation supporting the programme has been in place throughout but has not thus far mandated the slaughter of persistently infected (PI) calves. A key challenge in the early years, highlighted by modeling, was the retention of PI animals by some herd owners. This has largely been resolved by measures including graduated financial supports to encourage their early removal, herd-level movement restrictions, ongoing programme communications and the input of private veterinary practitioners (PVPs). A framework for funded investigations by PVPs in positive herds was developed to identify plausible sources of infection, to resolve the status of all animals in the herd and to agree up to three measures to prevent re-introduction of the virus. The prevalence of PI calves in 2013 was 0.66%, within 11.3% of herds, reducing in each subsequent year, to 0.03 and 0.55%, respectively, at the end of 2020. Recent regulatory changes within the European Union for the first time make provision for official approval of national eradication programmes, or recognition of BVD freedom, and planning is underway to seek approval and, in due course, recognition of freedom within this framework by 2023.

A Herd Investigation Tool in Support of the Irish Bovine Viral Diarrhoea Eradication Programme

“…36.4% of vaccinating beef herds and 25.8% of dairy used live vaccine. This is in contrast with details of annual vaccine sales, obtained through a market research company 3 , that showed that total doses sold in Ireland have experienced a 32.2% decrease since 2016/17, with sales of inactivated vaccines predominating (14). However, when the length of time in years that the vaccination regimen has been in place is analysed, between 42.3 and 49.4% of investigated herds through the years indicated they had been vaccinating for <1 year, which is considered to reflect the initiation of a vaccination regimen on the basis of the PVP's recommendation following the disclosure of the positive result.…”

“…Of the investigated herds, 15.7% reported a retained PI animal as the plausible source of infection, with this being more frequent in beef (18.3%) than dairy herds (12.4%). Retained animals were one of the key challenges in the early years of the programme (14,35). The introduction of a series of measures has largely resolved this issue, including graduated financial supports for their removal, movement restrictions, ongoing programme communications and the input of PVPs.…”

“…This would be the expected situation where the source of infection is internal to the herd, e.g., the presence of an unidentified BVD+ animal in the herd. (17), unidentified PI still present (14), and other species (18,19).…”

“…These dashboards are also available to Animal Health Ireland 2 (AHI) for programme management. Further details of the database functionality are described elsewhere (13,14).…”

“…An industry led compulsory BVD eradication programme began in Ireland in January 2013 after 1 year of voluntary participation. The programme is explained in detail elsewhere (13,14). Key elements include the identification and removal of persistently infected (PI) calves by testing all new-borns, the implementation of biosecurity to prevent re-introduction of disease and ongoing surveillance.…”