NFU Scotland is calling for a European Union-wide ban on the movement of female cattle and sheep of breeding age from bluetongue-infected areas into disease-free zones.

The call has been made in light of new scientific evidence of maternal transmission that has emerged following investigations into Northern Ireland's first case of the disease.

In Northern Ireland, imported cows had tested free of virus. However, their calves, once born, tested positive for live virus. It appears that the cows had been infected with bluetongue but had recovered and developed antibodies. However, whilst the virus was passed from cow to calf, it appears the antibodies were not, or they were ineffective.

Technically, these imported animals should never have arrived in Northern Ireland in the first place because a pre-movement test should have detected antibodies and prevented their export. However, once again, the testing regime has failed to provide adequate control. In light of all this, both the Republic of Ireland and Northern Ireland have introduced bans on the movement of these types of animals. NFUS is urging the rest of Europe to adopt the same precautionary approach.

Fortunately, Scotland currently slaughters any animal testing positive for antibodies. This provides a safety net here, but one that did not previously exist in Northern Ireland or currently exists in England.

The prospect of a bluetongue vaccine being available this summer raises questions over the importation of vaccinated animals. The vaccine being developed is not a marker vaccine so there is no way of determining if an animal has been vaccinated or previously infected with the disease. Whilst a vaccine may be effective on the mother, this week's developments raise questions as to whether it would be effective on the calf as well if it had been exposed to virus. These issues are to be discussed in Brussels next week.

NFUS president Jim McLaren commented: "The science of this disease is rapidly developing and we are learning more about it every day. The news that maternal transmission is a possible route of infection sets alarm bells ringing."

"Fortunately in Scotland we have a strict slaughter policy for any animal testing positive for bluetongue antibodies. However, that is not a defined policy south of the border or elsewhere and the testing regime is clearly not picking up danger animals before they leave the continent.

"All in all, I believe there are too many loopholes in controls and we need further strict action which, at the very least, must start with a ban on the movement of breeding females out of infected areas."