It is likely that bluetongue has moved beyond the current temporary control zone (TCZ) in NI, DAERA deputy chief vet David Kyle has said.

“We do think it has spread further than the zones which exist at the moment, but we just haven’t detected it yet,” Kyle said on Tuesday evening.

DAERA modelling indicates that anywhere between 16,000 to 30,000 cattle could have moved out of the current TCZ in the period between the virus first arriving and it being detected.

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“I would just caution the thinking that it is only in that small zone. I would be worried that it is elsewhere. It may already be in the south of Ireland, only they haven’t picked it up yet,” Kyle said.

At an online event organised by the Ulster Farmers’ Union, the DAERA vet said 5,500 samples from livestock have been tested from over 50 farms within the TCZ to date.

Four suspected outbreaks of the BTV-3 strain of the virus have been identified in Co Down so far, with the most recent being two cattle on a farm near Greyabbey.

“We certainly haven’t found all the infection that is there. Our statistics that we model would say about 10% of the herds in the zone will probably have some evidence of infection,” Kyle said.

He said DAERA are currently considering changing restrictions for farmers in the TCZ, including allowing livestock movements out of the zone.

“There may well be an announcement in the next few days on that. If movements outside the zone are to proceed, there are certain risk animals that will need to be tested,” he said.

Examples of high-risk animals include breeding bulls and rams, as well as pregnant cows and ewes. “If we let them go, they would need to be testing negative,” Kyle said.

Lessons from BTV-3 outbreaks in England

A survey of 68 farmers who were impacted by bluetongue in England found that severity of the disease on livestock was “relatively low”, said Gordon Hickman from Defra.

“Some farms did experience severe clinical signs and mortality [which was] directly or indirectly associated with bluetongue,” the UK government official said.

Speaking to UFU members on Tuesday, Hickman said common signs of the virus in sheep were dullness, lameness and a reluctance to move.

In cattle, dullness was also a common sign, as well as nasal discharge and crusting around the muzzle.

“Typically, those animals did recover, usually after a week or so, but there was some weight loss and almost certainly some production losses,” Hickman said.

In particular, a significant issue was the knock-on impact on fertility, especially in cattle. This includes higher empty rates, abortions, stillbirths and weak calves.

“Of the deaths that we know about, there were 61, with roughly half of these being euthanised for welfare reasons. Compared to the Netherlands, that is a very, very minor level of mortality,” Hickman said.

UK government figures indicate that there were 249 outbreaks of bluetongue on farms in Britain in 2025, with 576 animals testing positive.

However, Hickman acknowledged that the actual number of animals that were infected was much higher.

“We are just looking to identify premises where there is infection. Even in a report case, we are only sampling up to three animals,” he said.

He also pointed to results from recent surveillance work along the south coast of England where 68% of farms tested positive with at least one animal.

“On one of the farms in Kent, of the 14 animals we tested, 13 were positive. It is not unusual to get that high level of positive animals on an individual premises,” he said.

Ban on livestock imports from Britain to stay

The recent arrival of bluetongue to NI will not re-open trade in livestock from Britain to NI, a DAERA vet has said.

Livestock movements from Britain to NI have been prohibited since bluetongue was first detected in south east England in November 2023.

Speaking on the UFU webinar, Julian Henderson from DAERA explained that import bans are based on specific strains of the bluetongue virus, and not the overarching disease.

While NI has now had confirmed cases of the BTV-3 strain, other types have recently been detected in Britain including BTV-8 and BTV-12.

“Moves from GB to NI are governed by EU legislation on imports. The presence of BTV-12 in particular, is going to prohibit imports,” Henderson said.