If DAERA follows through on plans to end a surveillance programme for Maedi Visna (MV) in NI, the disease has the potential “to become the TB of the sheep world”, a representative of the National Sheep Association (NSA) in NI has claimed.

Addressing a meeting of farmers in Dungannon last Wednesday evening, Edward Adamson from the NSA warned the proposed funding cut will result in a less heathy, and less productive flock, in NI.

“It is at the opposite end to what we are supposed to do under climate change legislation. Our preferred option is to maintain the status quo,” said Adamson.

Unlike Britain, MV is a notifiable disease in NI, which means farmers here must report suspect cases to the Department. In addition, DAERA undertakes testing of sheep imported to local farms from across the Irish Sea, as well as from the Republic of Ireland (ROI), as it is not MV-free.

Back in November 2021, three rams from an NI flock tested positive for MV and there has been a small number of other cases since then.

However, NI has been able to retain MV-free status due to extensive testing, tracing and removal of infected animals by DAERA. It is understood that eight flocks were involved in this initial outbreak and put under movement restrictions whereby they can only send sheep for direct slaughter in NI or ROI.

If DAERA was to step away from its surveillance programme, there would potentially be nothing to stop these flocks selling live sheep to other farmers.

In addition, there is also a source of infection in ROI, as well as in Britain, although imports from there will not be possible in the short to medium term due to Bluetongue restrictions.

Quick spread

However, the evidence from across the Irish Sea is that once MV gets into the sheep population, it can spread quite quickly.

In 1995, around 1.4% of flocks in Britain had MV and by 2019 this had increased to 9.4%. On average in an infected flock, one quarter of sheep are affected and in the worst cases, this is as high as 70%, leaving farmers with little option but to implement a total flock cull.

According to local NSA representative, Campbell Tweed, there are fears in the north of England that MV is currently going through a period of “exponential growth”.

“Once it’s out and about, no-one can know whether it’s a safe animal to buy. It will only be a matter of time before we end up in the same place as GB,” he said. The Co Antrim farmer added it will be a “travesty” for NI producers if DAERA gives up on the control of MV.

Why MV should matter to all NI sheep farmers

Maedi Visna (MV) is a highly infectious viral disease that is mainly transmitted to lambs by ingesting milk from infected mothers, although it can also be spread by direct contact between sheep.

According to NI sheep vet, Paul Crawford, the main clinical signs are respiratory issues, which cause shortness of breath, and also mastitis, with udders that are hard and lumpy, although generally non-painful. Sheep can also develop neurological problems, where they are eventually unable to stand.

“They are very vague and non-specific signs of the disease. The most common sign in GB is thin sheep,” he said.

Sheep are usually infected early in life, but it might take a couple of years for clinical signs to develop, so there is a significant time window for the disease to spread.

In some cases in England, over 50% of the flock has been infected before farmers have realised there is an underlying issue.

A further complication is that none of the various tests for MV are 100% accurate and none will pick up all infected sheep. Sheep are infectious before they test positive for MV.

“The sheep don’t recover, there is no treatment and no vaccine. The damage to lungs is permanent and extensive. MV is a problem we don’t want in our national flock,” said Crawford.

However, he maintained that research does offer a “glimmer of hope”, with evidence pointing to some sheep having genetic resistance to MV.

In June 2024, Nottingham University confirmed it has received £1.1m in grant funding for a three-year project in conjunction with the Moredun Research Institute which will look at the potential to develop genetic resistance to MV within sheep flocks.

What are the future options for farmers?

The unanimous view of around 100 farmers at the Dungannon meeting was that DAERA should continue to undertake a MV surveillance programme in NI.

But if DAERA does decide to withdraw, how should industry respond?

Dr Sam Strain, the chief executive of Animal Health and Welfare NI (AHWNI) set out four main options, although he was clear that none are ideal, nor was he touting for business.

Do nothing

The first is a ‘do nothing’ approach. It is the cheapest option in the short-term, but with no controls, MV would slowly progress across NI.

Given that one of the main routes of transmission is close contact with infected sheep, the impact varies across farms, with extensively run flocks likely to experience less disease issues. However, “in some cases, losses will be substantial,” said Strain.

SRUC scheme

The second option is to join an accreditation scheme such as the Premium Sheep and Goat Health Scheme (PSGHS) offered by Scotland’s Rural College (SRUC).

New members to this scheme must undertake a set of qualifying tests in the first year, followed by periodic testing of breeding stock. The annual fee for flocks of over 51 breeding animals is £172.60, with each test costing £3.66 and not including vet charges to take samples. At present, there are 1,840 flocks throughout Britain listed on the SRUC database as MV accredited.

Accreditation schemes give a level of assurance to buyers around the risk of buying pedigree sheep with MV and also currently facilitate breeders who want to sell to MV-free countries (such as NI).

“The advantage is the scheme already exists and we understand SRUC are willing to include NI flocks. The disadvantage – it is not a control programme. It is only useful in those [pedigree] flocks in the scheme,” said Strain.

NI scheme

Rather than join the MV accreditation scheme offered by SRUC, the third option is to create a NI scheme, with local control and local oversight, suggested Strain.

However, he warned it would take time to build, would have to align with schemes in Britain and ultimately wouldn’t control the spread of MV in non-accredited, commercial flocks.

“The costs are not likely to be less – we don’t have economies of scale. It is not a cheaper option,” said Strain.

NI control

The final option is to create a MV control programme in NI and potentially widen it out to include other sheep diseases such as scab, OPA and footrot.

If all these diseases could be controlled at a low level in NI, it would obviously be of significant benefit for the entire sheep industry.

“The main disadvantage is cost – it is by far and away the costliest option,” said Strain.

A control programme would also come with various rules around issues such as biosecurity as well as testing and quarantine of purchased stock. In addition, an accreditation scheme would still be required for pedigree breeders.