Over the past two decades, Europe has experienced a dramatic and unprecedented increase in vector-borne diseases affecting livestock. What was once considered a problem confined to tropical and subtropical regions has gradually spread northwards, transforming the landscape of veterinary medicine across the continent. Climate change, globalisation and the growth of competent vector populations have collectively created an environment in which pathogens that European farmers and veterinarians were largely unprepared to face can flourish. The most significant of these emerging threats are bluetongue disease (BTV), Schmallenberg virus (SBV), epizootic haemorrhagic disease (EHD) and lumpy skin disease (LSD), each of which tells a unique story about how quickly the rules of disease ecology can change.
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Perhaps no disease illustrates the complexity of emerging vector-borne threats better than bluetongue, which is caused by bluetongue virus (BTV) and is primarily transmitted by biting midges of the genus Culicoides. Before the late 1990s, bluetongue was considered an exotic disease, largely absent from continental Europe. This changed when BTV serotype 2 emerged in Corsica and Sardinia in 1999, followed by other serotypes — BTV-1, BTV-4, BTV-9 and BTV-16 — which spread throughout the Mediterranean basin in the early 2000s (Purse et al., 2005; Barua et al., 2025).
The most devastating episode occurred in 2006 when BTV serotype 8 emerged in northern Europe — specifically the Netherlands, Belgium, Germany and France — a region where the disease had never previously been recorded. This was particularly alarming because northern Culicoides species, which were not previously considered to be competent vectors, were found to be capable of transmitting the virus (Carpenter et al., 2009). The epidemic spread rapidly, affecting millions of cattle and sheep and causing enormous economic losses, which triggered a large-scale vaccination campaign. Thanks to sustained vaccination efforts, BTV-8 was officially declared eradicated from most of Northern Europe by 2010. However, BTV-8 re-emerged in France in 2015 (Sailleau et al., 2015), demonstrating that eradication does not mean elimination of the risk. The virus can persist in low-level circulation in wildlife reservoirs or be reintroduced through animal movements.
More recently, two new serotypes have been detected in Western Europe, exhibiting very different epidemiological trajectories. BTV serotype 3 was first detected in the Netherlands in September 2023 and spread rapidly across Western Europe, reaching Belgium, Germany, France and the United Kingdom within months, before spreading to other parts of the continent, including Scandinavia (EFSA, 2024). This spread was both rapid and extensive, reminiscent of the 2006 BTV-8 outbreak, affecting tens of thousands of farms and resulting in severe clinical signs, particularly in sheep. This serotype is now considered to be widely established across Europe (plateforme-esa.fr).
By contrast, BTV serotype 12 followed a strikingly different and far more limited trajectory. Only five outbreaks were recorded in total — four in the Netherlands and one in England — before the virus appeared to fade without spreading further (WOAH, 2024). The reasons for this stark contrast with BTV-3 are not yet fully understood, but they likely reflect differences in vector competence for this specific serotype in northern Culicoides populations, intrinsic viral fitness and possibly the timing of detection relative to the midge season. This comparison between BTV-3 and BTV-12 serves as a powerful reminder that not all serotype introductions carry the same epidemic potential and that predicting which introductions will ignite large-scale outbreaks remains one of the central challenges of bluetongue surveillance.
In late 2011, a mysterious new disease began to affect cattle and sheep in Germany and the Netherlands. Calves and lambs were born with severe malformations, such as twisted spines, fused joints and brain abnormalities. The culprit was quickly identified as a previously unknown orthobunyavirus named the Schmallenberg virus (SBV), after the German town in which it was first detected (Hoffmann et al., 2012). SBV spread across Europe with remarkable speed, reaching the United Kingdom, France, Belgium, Italy and beyond within a year. The virus is also transmitted by Culicoides midges and causes teratogenic effects when pregnant animals are infected during a critical period of pregnancy.
The initial wave was severe, but subsequent years saw a gradual decline in clinical cases. Today, SBV is considered enzootically established in several European countries (Dominguez et al., 2014; Zeiske et al., 2025). Most adult animals have acquired immunity through natural exposure, and the disease now causes sporadic outbreaks rather than the explosive epidemics seen in its early years. Nevertheless, cohorts of young animals born after the initial wave remain susceptible, meaning that periodic resurgences are to be expected and must be monitored. SBV thus represents a classic example of a newly introduced pathogen transitioning from an epidemic to an endemic disease.
Epizootic Hemorrhagic Disease, caused by EHD virus (EHDV) and also transmitted by Culicoides midges, has long been known as a disease of white-tailed deer in North America. Its arrival in Europe was therefore a significant warning signal. EHDV was first detected in cattle in Sardinia in September 2022, before spreading to mainland Spain, Portugal and France in 2023, causing clinical signs including fever, oral lesions, lameness, and a significant drop in milk production in dairy cattle .
In 2024, new outbreaks were reported in Spain, Portugal and Northern France, confirming that the virus had not simply caused a transient epidemic but was establishing itself in Europe.
A particularly important development in the fight against EHD has been the demonstration of vaccine efficacy. Inactivated vaccines against EHDV serotype 8 — the strain responsible for European outbreaks — have shown promising results. Vaccination campaigns have been initiated in Spain, Portugal end France, and field data suggest that immunization was efficient to control the disease. Will the disease disappear from Europe (as BTV 12 has done), or will the virus follow the same path as the Schmallenberg virus (SBV) and become endemic? This is a question that will be crucial in the years to come.
Lumpy Skin Disease (LSD), caused by a Capripoxvirus and transmitted by various biting insects including stable flies, mosquitoes, and Culicoides midges, has historically been confined to Africa and the Middle East. Its westward progression has been alarming. After spreading through the Middle East and Turkey in the early 2010s, LSD reached southeastern Europe — Greece, Bulgaria, North Macedonia — in 2015 and 2016, before advancing further into the Balkans and Eastern Europe (Tuppurainen et al., 2017, Anses 2026). Vaccination campaigns proved effective in halting its advance in several Balkan countries, and for several years, Western Europe appeared to be safe.
However, the summer of 2025 marked a critical turning point. LSD was confirmed for the first time in Italy, with outbreaks detected in the northern regions of the country. This was shortly followed by the confirmation of cases in France close to the Italian border — the first time the disease had ever been recorded on French territory. The virus subsequently spread to northern Spain and southwestern France, completing a westward progression that many had feared but hoped that vaccination buffers in south-eastern Europe would prevent. These detections triggered emergency response measures in all three countries, including movement restrictions, emergency vaccination campaigns and heightened border surveillance.
The arrival of LSD in Western Europe serves as a stark reminder that geographical barriers no longer offer reliable protection against exotic pathogens, especially as vector populations expand and climatic conditions become increasingly favourable. Unlike the other diseases discussed in this article, LSD does not depend solely on Culicoides midges for its transmission, which makes it harder to predict and control. Vaccination with live attenuated vaccines has proven highly effective in endemic regions (Tuppurainen et al., 2017). The rapid deployment of vaccination alongside other measures in Italy, France and Spain has helped to stop the spread of the disease.
The common factor in all these diseases is the role of climate change and ecological disruption in facilitating their emergence. Warmer temperatures extend the seasonal activity of Culicoides midges and enable vector populations to survive at higher altitudes and latitudes. They also shorten the extrinsic incubation period of viruses within insect hosts (Purse et al., 2005). The result is a continent that is increasingly vulnerable to vector-borne diseases.
The epidemiological trajectories of these diseases also provide valuable insights into the range of potential outcomes following a viral introduction. Some pathogens, such as BTV-8 in Northern Europe, appear to disappear, only to re-emerge years later. Others, such as SBV, have established endemic cycles that necessitate continuous monitoring. The future of other pathogens, such as BTV-3 and EHD, remains uncertain as they have only recently emerged. Some, like BTV-12, seem to extinguish themselves after only a handful of outbreaks, though the reasons why remain unclear. The key message for policymakers, veterinarians and farmers is this: disappearance does not mean eradication. Even when clinical cases are absent, surveillance must be maintained, vaccination programmes must be sustained, and contingency plans must be kept ready for pathogens that have seemingly vanished.
Vector-borne diseases have become a major animal health challenge in Europe over the past 20 years. Their emergence and spread highlight the growing influence of climate, vector ecology and animal movements on disease dynamics.
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