Norfolk's bluetongue case total has risen to 25 after more cattle were confirmed to have caught the dangerous animal disease.

Defra has identified four new cases of bluetongue in cattle which had been grazing within the Norfolk temporary control zone (TCZ), east of Norwich.

The zone was created after the initial discovery of the disease on a farm near Cantley in the Broads on December 8.

It was extended on Saturday after infected animals were found to have grazed on land just outside the zone during the high-risk period.

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

It is believed the disease was carried to Norfolk by infected biting midges, blown across the Channel from Europe during optimum wind and temperature conditions in September or October.

Unlike previous cases, the recently-diagnosed animals will not be culled, but will be "restricted at their current locations and disease mitigation measures will be taken".

Defra says this "reflects a recent reduction in midge activity, reducing the risk of onward transmission". There is still no evidence the disease is circulating in midges in the UK, it says.

Bluetongue is a potentially fatal virus affecting ruminants including cattle, sheep, goats, deer and camelids - but health officials say it does not affect human health or food safety.

However, the precautionary measures in the Norfolk TCZ are causing disruption and uncertainty for livestock farms, as specific licences are now needed to move animals out of the zone, which are only permitted where there is an "urgent and genuine welfare need”, or to go directly to slaughter at a designated abattoir.

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

For more information and advice, see the bluetongue pages at www.gov.uk, visit Ruminant Health and Welfare’s dedicated bluetongue web page, or call the bluetongue advice hotline on 024 7771 0386.