A new suspected case of bluetongue virus (BTV) has been discovered on a farm near Greyabbey in County Down, the Department of Agriculture, Environment and Rural Affairs (Daera) has said.

Vets are investigating a suspect case of the virus in a cow which sits in the existing 20km Temporary Control Zone (TCZ) around a holding near Bangor where the virus was initially discovered.

As a result, a second 20km TCZ is being introduced around the Greyabbey farm and is effective from 18:00 GMT on Saturday.

Spread by midges, bluetongue poses no threat to the public or food safety but can affect cloven-hoofed animals like sheep and cattle.

Daera veterinary officer Ignatius McKeown said it was “difficult to say at this stage” how many cases of bluetongue will be found.

“Certainly that second case of bluetongue has extended our surveillance area so we will be carrying out investigations throughout the area,” Mr McKeown said.

He encouraged farmers to be “vigilant” and “aware of the signs of bluetongue”.

“Swollen face, a fever, lameness, drooling and crusting of the nostrils – if you do come across any of those clinical signs ring the department immediately and we will investigate.”

Daera Minister Andrew Muir said the emergence of the suspect case in the existing TCZ was “very disappointing – especially for the farmer concerned”.

He described the introduction of a second TCZ as an “essential measure”.

“This suspect case serves as another reminder of why farmers need to be extra vigilant for clinical signs of bluetongue in their flocks or herds.

“As vets continue their investigations, I and my officials will continue to work closely with stakeholders in the agri-food industry, as well as our counterparts in the Irish, UK Scottish and Welsh Governments as we respond to a rapidly evolving situation,” Muir said.

Chief Veterinary Officer Brian Dooher added: “Bluetongue is an unpredictable virus that is spread by midges through and between flocks and herds.

“The spread of bluetongue has a significant impact on livestock, the agri-food sector and the rural economy.

“I would urge everyone in the farming industry to continue to play their part in protecting our farms by remaining vigilant and would especially urge those in the TCZs to follow the restrictions,” Mr Dooher said.

Ulster Unionist Party (UUP) agriculture spokesperson Robbie Butler said the suspected case “reinforces the scale and urgency of the challenge we now face”.

“It is more important than ever that Daera offers not just guidance, but absolute cooperation, coordination and practical support to every farm and every community affected.

“This must be matched by full engagement from all stakeholders across the agriculture and agri-food sector,” Butler said.

Analysis: BBC News NI Environment Correspondent, Louise Cullen:

The detection of another case is not surprising, given how this disease spreads. It was always the expectation that more would come.

But the location of the new control zone and its subsequent movement restrictions will raise concerns.

Saintfield livestock mart which is firmly in the original zone has already been suspended.

While this new zone does not affect any others, it is worryingly close to Ballynahinch, where another livestock mart is located.

The minister warned last week that he would consider extending the zone across Northern Ireland as and when new cases emerge.

That is something he may find himself having to implement sooner rather than later to ease the management of animals on farm.

Bluetongue virus affects cattle, goats, sheep, deer and camelids such as llamas and alpacas.

It can cause ulcers or sores around the animal’s mouth and face, difficulties swallowing and breathing, fever and lameness, foetal deformities and stillbirths.

It is a notifiable disease so anyone suspecting their animals may have it must report it to a vet, local divisional veterinary office or to Daera directly.

The latest outbreak began in the Netherlands in 2023, where tens of thousands of sheep died, and midges blown over from the continent began infecting livestock in the south-east of England too.

But the impact of BTV-3 seems to vary considerably across different regions, with some animals showing little sign of infection and managing to recover.