The BVD eradication programme is working in rapid fashion. Numbers of infected animals and herds are falling and farmers are getting an increasing financial payback.

The programme is on target and looks set to be a good investment by farmers and the state. There is an issue about visibility on the money: the costs of the programme are very apparent to an individual farmer –while the benefits are not.

The €9m cost per annum includes the cost of tissue tags, lab testing for the disease and the culling of PI calves. A farmer dips his hand in his own pocket for these and then there is the hassle as well.

The payback is over €85m in 2018 alone and should be €100m each year after eradication. This is made up of better herd health and animal performance and fewer vet and medicine bills. It is now benefitting dairy, suckler and finishing herds. But it does not come to you as a wad of notes in an envelope from “Mr BVD Programme”.

All of these figures come from AHI – but any doubting Thomas should remember that the farm organisations are involved in the management of the programme and watch these various issues carefully.

The cost figure also includes the administration side as handled by Animal Health Ireland.

2020 target

If present efforts continue, the disease will be eradicated in two years’ time, on target, according to Dr David Graham, chief executive of AHI.

Here are the latest figures:

By early December 2018, just over 2.25 million calves have been tested, approximately 98% of the anticipated calf crop for the year. Prevalence of PI births in 2018 continues to decline, with only 1,254 or under 0.06% of calves tested being found to be PI. These were located in 1.1% of 83,000 breeding herds.

This represents a decrease in PI prevalence of almost 50% from that seen in 2017, from 0.10% to 0.06% nationally, and is a reduction of more than eleven-fold when compared with the prevalence at the start of the compulsory phase of the programme in 2013.

To further put the progress in context, the number of PI calves born five years ago, in 2013, was almost 14,000. The number of positive herds was 9,485.

Several counties currently do not have any known PIs present. There are 37 PIs remaining alive.

Looking into 2019, it is critical to the programme’s continued progress that all calves are tested as soon a possible after birth, and that all PIs identified are removed as rapidly as possible, Dr Graham says. Nationally, the prevalence of PI births varied from 0.03% (Carlow, Clare, Cork, Kilkenny, Waterford and Wicklow) to 0.12% (Monaghan and Offaly).

What next?

The national BVD model indicates that eradication is achievable by 2020 assuming compliance with legislation and programme requirements, but eradication is not achieved in all simulations.

Prompt detection (through early tagging) and removal of PI calves are critical factors influencing the rate of decline in the number of PI calves born each year. Additional measures, which could contribute further, include prevention of herd to herd spread through the movement of Trojan dams. These are pregnant females that are not themselves PI but are carrying a PI calf.

Taking the above into consideration, and also the requirement to anticipate the needs of the programme as eradication is approached and achieved, the BVD Implementation Group is currently considering recommendations from the technical working group on enhancements to the programme in 2019.

These include a focus on ensuring that all calves are sampled and tested as soon as possible after birth, that positive calves are removed as rapidly as possible and that the small numbers of untested animals, including some born prior to 2013 (and therefore not covered by legislation) are addressed.

Preventing reintroduction

When the country is free of BVD, the focus will switch from mandatory sampling and testing of all calves to preventing reintroduction.

Surveillance measures will be necessary to monitor freedom from disease as well as the prompt detection of reintroduction of BVD.

After eradication, the main risk is the introduction of BVD-positive animals or Trojan dams. One of the proposals that the BVD Implementation Group is now considering is to recommend new legislation that would require all imported animals to have a negative BVD test.

Occasional PI cattle imports are already being detected. Blood samples being taken from imported animals for general surveillance purposes are also being tested for the BVD virus. This highlights the need to both maintain and enhance testing of imported cattle.

Department of Agriculture figures for 2017 show that 3,113 cattle were imported, with the majority of these coming from the UK and, in particular, Northern Ireland. That excludes animals that went directly for slaughter. In fact, a number of measures already result in approximately 80% of imported breeding cattle being subject to a post-import test.

Firstly, current legislation prevents the movement of animals born after 1 January 2013 in the absence of a negative test result. Imported animals born after this date may not leave their importing herd without being tested.

Secondly, while they are not compelled to be tested if staying in the importing herd, the introduction of animals of unknown status will generate programme reminders to herds that have acquired negative herd status to test these imported animals.

Vaccination

The main purpose of BVD vaccination is to induce a protective immunity in breeding animals to avoid a range of negative outcomes of infection on reproduction, most importantly the creation of PI calves.

Vaccination acts as a protective measure should a breakdown in biosecurity occur. However, it should be noted that the available BVD vaccines will not provide 100% protection in all circumstances, even when stored and used correctly, particularly where pregnant cattle are exposed to high levels of BVD virus.

Decisions on the use of BVD vaccine, including when to stop a vaccination programme, are herd-specific and should be taken by each farmer in discussion with their own veterinary practitioner.

Key factors for consideration include the likelihood of introduction of infection. Introduced animals, particularly if in calf, are the single biggest risk. The risks from other means of introducing the virus include direct contact between cattle (eg at boundaries, shows and sales) and indirect contact (eg on the clothing, boots or hands of the farmer, employees or visitors or through contaminated equipment or environments) should also be considered.

So another issue under consideration by the BVD Implementation Group is the impact of vaccination on future surveillance, due to the inability to consistently distinguish between animals that have been vaccinated rather than infected.

For this reason, the group is currently considering how best to capture the vaccination status of herds.