The Department of Agriculture, Food and the Marine (DAFM) has urged livestock keepers to be vigilant as increasing temperatures bring increased midge activity and, therefore, a higher risk of bluetongue virus (BTV).
Bluetongue is spread by infected biting midges of the species Culicoides, which are present in Ireland and are generally most active between April and November.
As temperatures begin to rise in spring and into summer, the risk of bluetongue transmission in Europe increases.
Bluetongue affects ruminants like sheep, cattle, deer and goats. It also affects camelids (such as llamas). Several cases were reported in England late last year and early this year, resulting in authorities there establishing control zones that restricted animal trade and movement.
This also resulted in the suspension of movement of bluetongue-susceptible animals (including all cattle and sheep) between the island of Britain and the island of Ireland, a suspension that remains in effect.
The virus does not affect people or food safety, but outbreaks can result in prolonged animal movement and trade restrictions.
In its latest information update on the disease, the department here said that increasing temperatures result no only in an increase in midge activity but also the ability for the virus to replicate in the midge, which requires temperatures of between 12° to 15°.
The department said: “It is critical that over the coming months, all livestock farmers maintain vigilance for any suspicions of bluetongue virus, and report any such suspicions to their local regional veterinary office without delay.”
Signs of bluetongue infection include:
- fever;
- loss or lack of appetite;
- drop in milk yield;
- reddening of mucus membranes;
- sores on noses, gums and dental pads;
- Swelling of face, lips and tongue;
- drooling;
- discharge from eyes or nose;
- Lameness;
- abortion or deformities in offspring/foetus.
However, infection might be present without clinical signs.
Ireland is currently BTV-free. However, the disease could spread to Ireland through the importation of infected animals, infected animal foetuses, germinal products (semen and ova); or though wind dispersal of infected midges from mainland Europe.
Until recently, there was no vaccine for the serotype of BTV responsible for the series of outbreaks in England. However, in recent days, a vaccine developed by a Spanish pharmaceutical company received emergency authorisation from the EU for use in the Netherlands.
However, it is not approved for use across the EU generally, nor is it available outside of the Netherlands.
Meanwhile, the UK’s Department of Environment, Food and Rural Affairs (Defra) announced on April 19 that Britain is no longer in the seasonal ‘low vector period’, meaning the risk of spread of the disease is increasing as warmer weather approaches.
Currently, there is no evidence of bluetongue circulating in midges in Britain. There has not been a case reported in livestock there since March 15, and there are currently no control zones in force.
Of the 126 cases (119 cattle and seven sheep) reported across 73 premises in four English counties since the outbreak began in November, none displayed any clinical signs of the disease, and the initial cases were discovered through routine testing.