Farmers need to remain vigilant against the threat of bluetongue disease, the Chief Veterinary Officer (CVO) at the Department of Agriculture in the North has said.
Robert Huey has urged farmers not to import cattle from affected countries.
"Unfortunately in recent weeks there have been isolated incidents of farmers importing cattle from European countries affected by bluetongue.
"There are inherent risks associated with this and I would urge farmers not to import cattle from affected countries.
"The potential cost to the agri-food industry of a bluetongue outbreak has previously been estimated at as much as £25m per year.
"Responsible sourcing of livestock is critical to the maintenance of our high animal health status and ability to trade," he said.
Huey said that to date the actions of the Department of Agriculture and Rural Development's (DARD) Veterinary Service, alongside its counterparts in the south, in addition to the actions of responsible farmers, have been successful in maintaining bluetongue free status on the whole island of Ireland.
"It is vital that the necessary precautions are taken to ensure this status is retained," Huey said.
The bluetongue virus is spread by midges which transfer the virus from animal to animal by biting them or by infected germplasm (semen or ova), according to DARD.
Bluetongue affects all ruminants, such as cattle, goats, deer and sheep and clinical signs can vary by species - although symptoms are generally more severe in sheep, it stated.
Symptoms include fever, swelling of the head and neck, lameness, inflammation of the mucous membranes of the mouth, nose and eyes, drooling and there is often a high mortality rate.
Generally cattle and goats are less severely affected but cattle and goats, which appear healthy, can carry high levels of the virus and provide a source of further infection, DARD stated.
According to DARD, animal keepers in Northern Ireland are not permitted to vaccinate their animals against bluetongue.
However, if bluetongue was confirmed in Northern Ireland, a veterinary risk assessment would be carried out and a licence may be issued to permit vaccination, it stated.
DARD advised that vaccination against one strain of Bluetongue virus does not give protection against any other strain.