Bluetongue BTV-3 spreads to Ireland and continues across Great Britain in 2025-26 midge season

Summary

Bluetongue virus serotype 3 (BTV-3) continued its northward expansion in 2026, reaching Ireland for the first time. A cattle herd in County Wexford tested positive in January 2026, marking the first confirmed case in the Republic of Ireland. In Great Britain, the 2025-26 midge season (counted from July 1, 2025) produced 347 confirmed cases by late June 2026: 323 in England (310 BTV-3 only, 5 BTV-8 only, 7 with both serotypes), 1 in Wales, and 5 in Northern Ireland. The most recent case, confirmed June 23, involved a calf in Lancashire born blind on June 1. BTV-3 first reached Great Britain in the 2023-24 season originating from the Netherlands; this is the second full midge season of UK circulation. The disease does not affect humans but causes fever, swelling of the jaw and tongue, hemorrhages, abortions and congenital deformities in ruminants, and carries a significant mortality rate in sheep. Vaccination against BTV-3 is available and permitted across the British Isles as of January 1, 2026.

The split

UK farming press and the Agricultural and Horticulture Development Board tracked the case-by-case spread with particular concern for sheep flocks unprotected by vaccination, noting vaccination uptake as the critical variable. Irish farming media framed the Wexford detection as a turning point, since Ireland had previously been free of the disease and was dependent on trade access linked to its status. Northern Irish agricultural bodies highlighted trade complications from BTV-3 detection given cross-border livestock movement with the Republic and rules on livestock export from infected zones. European veterinary science journals covered the season's spread as evidence of a sustained northward shift in midge range linked to milder Atlantic winters.

By the numbers

• 347, total bluetongue cases in Great Britain in the 2025-26 season (as of June 23, 2026)
• 323, cases in England (310 BTV-3 only)
• 5, cases in Northern Ireland
• 1, case in Wales (May 28, BTV-3, Ceredigion)
• January 2026, Ireland's first ever confirmed bluetongue case (Wexford)
• March 31, 2026, date midges became active again in the UK
• January 1, 2026, date BTV-3 vaccination permitted in Ireland

Why it matters

The northward spread of Bluetongue in successive midge seasons is consistent with the warming of Atlantic Europe and has direct consequences for the British Isles livestock trade, which depends on disease-free certification for export to the EU and other markets. The simultaneous presence of BTV-3 and BTV-8 in England increases the complexity of vaccination programmes and the risk of viral reassortment. Ireland's first detection ends its historical freedom from the disease. Trade restrictions that follow confirmed cases affect sheep and cattle exports, imposing economic costs on producers in affected zones even where clinical illness rates are low.

What to watch

• Whether the 2026 midge season produces a higher total case count than 2025-26
• Vaccination uptake rates in England, Wales and Ireland and their effect on outbreak containment
• Trade restriction decisions by the EU in response to confirmed BTV zones in the UK
• Whether BTV-8 spreads more widely in England and whether co-circulation produces reassortant strains