Bluetongue infections on Norfolk livestock farms continue to rise, with 13 new cases confirmed in the last three days.

Defra says ongoing surveillance has identified the potentially-fatal animal disease in seven cattle near Norwich on Sunday, and six near Hales on Friday and Saturday.

It is believed the virus was carried here by infected midges, blown across the Channel from Europe during September or October.

Last Thursday, the government announced that the risk of disease transmission had dropped in the colder weather, as midges which carry the disease are not actively feeding.

That prompted a relaxation of some of the livestock movement restrictions in the 10km Norfolk Temporary Control Zone (TCZ) which was created around the county's first case near Cantley on December 8, and extended slightly last week.

Eastern Daily Press: Norfolk's bluetongue temporary control zone (TCZ) was extended on January 27Norfolk's bluetongue temporary control zone (TCZ) was extended on January 27 (Image: Defra)

The surge in new cases brings East Anglia's total to 42 within a national total of 83, across both TCZs in Norfolk and Kent.

However, despite this, animal health officials say there is still no evidence that bluetongue virus is currently circulating in midges in Great Britain.

Due to the recent cold weather, we are now in a "seasonally vector low period, when midge activity is much lower, and they are not actively feeding", says Defra.

Movement restrictions which have been causing disruption and uncertainty for Norfolk livestock farms were eased last week, with licences now available to move animals out of the zone, subject to pre-movement testing and other conditions.

Defra said these licences will "only apply during periods of low vector activity and will not apply to animals that test positive in a pre-movement test".

Another change in disease precautions is that positive infected animals are no longer being culled, but will be restricted at their current locations and "disease mitigation measures" taken.

Although bluetongue does not affect human health or food safety, it is potentially fatal to ruminant animals including cattle, sheep, goats, deer and camelids.

Livestock keepers must report suspicions of the virus immediately to the APHA on 03000 200 301.