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Bluetongue: Steps to minimise and deal with the disease

Tirlán veterinary advisor, Joris Somers, provides some key guidance to farmers on what actions they can take to protect their animals from bluetongue this spring and into the summer months, and we provide an update from the Department of Agriculture, Food and the Marine (DAFM) on the status of the disease in Ireland 

Irish livestock farmers are on high alert since the outbreak of bluetongue virus (BTV) serotype 3 (BTV-3) in a number of cattle herds last month.
The first case was detected in Co. Wexford through the culled cow routine surveillance in a slaughterhouse, according to the DAFM. Subsequently, three nearby farms were also reported to have the virus. The virus is spread by culicoides midges, also known as biting midges, which are most active during April to November, demanding heightened vigilance and preparedness. These infected midges not only act as a means of transport for the virus, but are also a biological vector, meaning the virus replicates and multiplies inside the midge. For this to take place, sustained temperatures above 12°C are needed, hence the current lower risk of BTV-3 spreading widely. However, Irish summers now regularly exceed this threshold, increasing the likelihood of virus amplification in even a single infected midge.

Remember

Bluetongue is a notifiable disease, and early detection is essential for protecting the national herd. Key signs include fever, reduced appetite, drop in milk yield, drooling, swollen lips or tongue, lameness, discharge from the nose or eyes, breathing difficulties, abortion or deformities in offspring/foetus and, in severe cases, death can occur.  Sheep tend to be more severely affected than cattle and observations from the UK would indicate that the current BTV-3 strain is causing less prominent signs compared to the early days of the outbreak in The Netherlands. Any suspicion must be reported immediately to your local regional veterinary office.

Vaccines

Recognising the increased risk, BTV-3 vaccines have been authorised to use in cattle and sheep in 2026. The same vaccines have been used successfully in UK and The Netherlands to limit the impact of BTV-3 on livestock. These vaccines do not eliminate the spread of the virus but mitigate the health impacts of the disease on cattle and sheep. Farmers looking to vaccinate livestock should discuss this with their veterinary practitioner and aim to have this completed before peak midge season later this spring.

Important

There are no food safety or human health risks from bluetongue. Milk and meat are safe to consume.

Meaningful steps

Because vaccination doesn’t eliminate the impact or spread of BTV-3, a combined approach of vaccination plus biosecurity remains essential to control this disease. If purchasing animals, for example, during the higher-risk April to November period, farmers are advised to request pre-movement PCR testing and implement short-term isolation on arrival. And, while midges cannot be eradicated from the Irish countryside, farmers can take meaningful steps to reduce contact between livestock and biting insects. These are outlined as follows:

  • House animals at dusk, when midge activity peaks.
  • Improve airflow in sheds and handling areas.
  • Reduce wet, manure-rich zones around buildings and yards; these are ideal breeding habitats for midges.

Consider pyrethroid-based pour-ons in consultation with your veterinary practitioner. These can reduce biting pressure but should not be relied upon as the sole control measure.

Pregnant animals

Infected pregnant animals can pass the virus to their unborn offspring in the womb. These can be a source of infection when they are born.
Source: DAFM.

Positive animal showed no clinical signs

At the time of print, the DAFM's National Disease Control Centre issued the following update in relation to the first occurrence of BTV-3 infection in a cattle herd in Wexford.

  • Detection was achieved through routine surveillance conducted by DAFM under the culled cow scheme.
  • Blood samples collected from a suckler cow that was to be culled were tested serologically, and antibodies to bluetongue virus were detected.
  • Subsequently, additional animals from the herd of origin were blood sampled for testing.
  • Testing by the Reference Virology Laboratory confirmed positivity of an additional animal by PCR, and serotype 3 was confirmed.
  • Positive animals did not show clinical symptoms.
  • Positive animals were not imported.
  • Likely source of incursion is by infected midges blown across the Irish sea.
  • No restriction zones had been introduced (at the time of print) due to the low transmission risk associated with current environmental temperatures.
  • At the time of print, it was reported that three farms located near the initial farm had confirmed cases of bluetongue.

Impact of bluetongue on trade

Movements of live susceptible ruminants within the EU

  • The following countries specify no additional conditions for BTV-3: Belgium, Croatia, Czech Republic (confined establishment moves only), France, Germany, Hungary (confined establishment moves only), Luxembourg, Netherlands and Spain.
  • Italy and Portugal specify that if the serotype is present at destination, they have no specific conditions. BTV-3 is present in both Italy and Portugal.
  • Movement direct to slaughter – allowed if they come from establishments in which infection with bluetongue virus (serotypes 1-24) has not been reported during the last 30 days prior to the date of departure of the consignment.
  • Movement of live susceptible animals for breeding and production to other EU member States MAY be possible if the Member State is not BTV free and allows derogations from BTV requirements.
  • Northern Ireland (NI) – BTV 3 vaccines do not have an established duration of immunity so cannot be used as a basis for certification currently. The DAFM is engaging with its counterpart, the Department of Agriculture, Environment and Rural Affairs (DAERA).

Movements of live susceptible ruminants to third countries

  • At the time of print, beef market access to China had closed due to the outbreak of bluetongue here.
  • In general, third country (non-EU) bilateral animal health certificates require country freedom from bluetongue for a period of 12 to 24 months. The DAFM is engaging with competent authorities of third countries.
  • Great Britain (GB): BTV-3 vaccines do not have an established duration of immunity so cannot be used as a basis for certification of live animal movements. The DAFM is engaging with its counterpart, the Department for Environment Food and Rural Affairs (DEFRA).

Dairy products

  • No implications for dairy products to be exported to GB, NI or the EU.

Germinal products (semen, ova, embryos)

  • The DAFM is issuing a sector specific update (at time of print). It is important to note that importing semen from affected countries is not without risk

REPORT WITHOUT DELAY

To report a suspected case of bluetongue, contact your local regional veterinary office or call the national disease emergency hotline on 01- 492-8026 (outside of normal office hours) without delay.

All the above information was correct at time of print. For updates, please refer to www.gov.ie/bluetongue.

Additional reporting by Bernie Commins.

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