Farmers still have time to vaccinate against bluetongue virus ahead of the high risk season this year, a senior Department of Agriculture official has advised.

“I would say to farmers that if you haven’t vaccinated by now, I wouldn’t rule it out,” Avril Hobson, senior superintending veterinary officer at the Department said.

“We recommend that you talk to your vet about it.”

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The vaccine does not prevent animals contracting bluetongue, but it does reduce the symptoms on vaccinated livestock.

The recent warm spell is unlikely to have kickstarted the high risk period, which usually runs from April to November.

“The research shows you have to have temperatures over 12°C for the virus to replicate, but it’s not black or white. As temperatures increase, it will replicate in the midges faster,” Hobson, who is also the head of the National Disease Control Centre at the Department, said.

“The last couple of days have been warm during the day, but quite cold at night. Temperatures need to be greater than 12°C for a sustained period for the virus to replicate within the midge so that the midge can spread the virus.

“We are getting into the warmer period of the year, but we’re not quite there yet,” she said.

Hobson indicated that it is difficult to predict how and when a plume of infected midges might hit these shores in the higher risk period this year.

Infectious plumes

She outlined to the Irish Farmers Journal that a plume of infected midges blowing over into Ireland from the UK or the continent is dependent on a number of factors, the speed and height of the wind being one.

“It’s difficult to model, but we have the evidence it has happened at least once,” she said.

Hobson added that the risk factor is also combined with how many infected midges are currently resident in Ireland but effectively dormant from spreading bluetongue until temperatures heat up.

From July, the disease will be recategorised at EU level from a C disease to a D and E disease.

This change essentially means that the disease will move to a disease which is under surveillance from one which can be eradicated.

“The disease doesn’t know it has been recategorised. The risk of the disease does not change when it is recategorised in July, it can still cause fertility issues and abortions although it is unclear how significant the clinical signs will be,” she said.

“It’s no longer a category of disease that Ireland can declare freedom from,” she said.

She said that health certificates for exports are all being changed to reflect this.

For trade, Hobson said that these changes allow member states to have greater flexibility to set the requirements or derogation conditions to accept animals from Ireland.

These conditions will be set by the competent authorities in the relevant country.

The change in status of the disease does not mean farmers should stop vaccinating for bluetongue, Hobson advised.