County Carlow remains BVD-free to date, joined by County Sligo, while a number of other counties have only a single herd with positive results, according to AHI (Animal Health Ireland).
However, there are areas with higher levels of infection in NI particularly along the Co Armagh border with Co Monaghan.
A map produced by the Centre for Veterinary Epidemiology and Risk Analysis (CVERA), University College Dublin, displaying the distribution of herds with positive test results for BVD virus, shows the marked progress made by the ROI and NI BVD Eradication Programmes to the end of 2022.
These programmes are similar in design, based on mandatory testing of tissue samples collected and submitted by herd owners using tissue-sample enabled national identity tags.
The programmes became compulsory in ROI in 2013 and in NI in 2016, with both being overseen by stakeholder Implementation Groups.
The anonymised maps are an outcome of ongoing collaboration between Animal Health Ireland (AHI) and Animal Health and Welfare NI (AHWNI) who co-ordinate the respective programmes, and DAERA and DAFM.
AHWNI chief executive Dr Sam Strain commented that the maps demonstrate the “substantial advances that have been made in tackling BVD” through both programmes.
The animal-level incidence of BVD within NI has fallen by over 70% since the start of the compulsory programme to 0.264% in 2022, with these being found in 3.76% of herds.
Crucially, the number of Persistently Infected animals that have been retained following identification has dropped “dramatically” in the last year, thus reducing the infection pressure on affected farms and their neighbours.
Dr Strain added that this reflects the “enormous efforts of farmers and industry partners in addressing the infection, despite the limited” resource and legislative tools currently available to address all the infection risks that are present.
According to AHI Programme Manager Dr Maria Guelbenzu, during 2022 only 0.031% of calves tested returned a positive result, with these being found in only 308 (0.45%) of all breeding herds in ROI.
This highlights the “significant” progress made since 2013, when 0.66% of calves from almost 9,000 herds tested positive.
“2022 was the first year in which any county recorded no positive results, with this honour going to Carlow,” Dr Guelbenzu added.
“This progress is a testament to the ongoing effort and commitment of participating farmers and wider stakeholders,”
The programme continues to make progress during 2023, according to Dr Guelbenzu.
At the end of July, 2.1 of the 2.4 million calves (88%) due in 2023 had been tested, with positive results returned from fewer than 200 herds.
BVD freedom – the goal
Dr David Graham, chief executive of AHI, added that “following approval of our eradication programme by the European Commission in 2022, the goal is now to reach the position where an application for recognition of freedom can be made. For both programmes, continued implementation of key measures is required to ensure further progress”.
“It is vital that calves continue to be tagged and samples submitted promptly for testing, allowing infected calves to be identified and removed as quickly as possible, alongside efforts to prevent accidental transmission of BVD virus to other herds.”
This may occur through the movement of animals which may be undergoing a transient infection, or which are pregnant and carrying a persistently infected calf.
Transmission may also occur via contact at boundaries, or through the movement of contaminated equipment or people between herds, including professional visitors, staff, and farm family members, in the absence of appropriate hygiene measures.
While it is important that all herds take measures to prevent the accidental introduction of infection, the higher levels of infection in NI, as compared to ROI, mean that herds in border regions, particularly in Monaghan and Louth, need to be “especially careful”, given their proximity to infected herds in NI.