The one health threat of African horse sickness: Are Europe or the Middle East next?
Year: 2025
Type: article
Abstract: The question ‘The One Health Threat of African Horse Sickness: Are Europe or the Middle East Next?’ is more than just rhetorical—it underscores the interconnected nature of our world and highlights the pressing need to tackle transboundary animal diseases through a comprehensive One Health approach. While African Horse Sickness (AHS) is not zoonotic, the indirect human impact is profound. The loss of horses leads to economic hardship, loss of cultural heritage, and disruption of agricultural systems, especially in rural communities that rely on equids for transport, farming, and income generation, as well as the multi-billion dollar racing, breeding, and leisure horse industries. Moreover, the globalisation of trade as well as equestrian sport events and climate-driven shifts in vector distribution increase the risk of AHS spreading beyond endemic regions, reinforcing the urgency for coordinated international surveillance and response efforts.1, 2 In this context, the High Health, High Performance (HHP) framework, which enables the international movement of elite horses under strict vaccination and biosecurity protocols, highlights both the opportunities and challenges of balancing the mobility of horse shipments with disease prevention.3 African Horse Sickness is a viral, vector-borne, non-infectious and devastating disease threatening equids (WOAH-notifiable disease category A).2 It is caused by African horse sickness virus (AHSV), a virus species within the genus Orbivirus in the family Reoviridae. AHSV, like the prototype bluetongue virus (BTV), has a 10-segmented genome of double-stranded RNA and is mainly transmitted by competent biting midges of the species Culicoides. There are nine distinct serotypes of AHSV, AHSV-1 to AHSV-9, defined by serotype specific protection.4 AHSV can undergo genetic reassortment in doubly infected cells, potentially leading to the emergence of novel virulent strains.5 AHS is historically largely confined to sub-Saharan Africa, but this geographical boundary is eroding. Driven by climate-induced shifts in vector distribution and ecology AHS is a rapidly expanding transboundary threat: recent outbreaks in Nigeria (December 2022), Kenya (February 2024), Mozambique (March 2024), and Tunisia (October 2024) and Namibia (May 2025) are a clear warning. AHS has expanded outside Africa not for the first time (India and Pakistan in the 60s and the Iberian Peninsula in the 80s) into Thailand in 2020.6-8 This correspondence argues that AHS represents an imminent and multifaceted One Health crisis for Europe and the Middle East, demanding urgent, coordinated, and proactive intervention. Should AHS establish in Europe and the Middle East, the impact would be nothing short of catastrophic. With extremely high mortality rates reaching up to 95% in naïve horse populations, the scale of potential loss is staggering.4 Beyond the economic impact, the disease causes severe pain and poses a serious animal welfare concern.9 This is not only about animal welfare but also about the equine-dependent industries. Equestrian sports, a significant economic and cultural force across Europe, America and the Middle East would face unprecedented disruption through movement bans, event cancellations, and the tragic loss of high-value animals. Beyond sport, the burgeoning horse meat industry in some European nations (Romania, etc), and more critically, rural transportation in regions still reliant on working equids would be crippled. The psychological impact on horse owners, witnessing the devastating loss of many beloved animals, would be profound. The economic burden imposed on communities, particularly in countries where horses play a vital role in agriculture and daily life such as African, Middle Eastern and Balkan countries, could be immense. Trade restrictions and shattered livelihoods would create a domino effect, extending far beyond the immediate health crisis. The One Health concept recognizes that the health of people, animals, and our shared environment are inextricably linked.10 It emphasizes a collaborative, multisectoral, and transdisciplinary approach to addressing health challenges on a global level. The modern global horse industry is characterised by increasingly frequent international movements of equids for purposes including racing, breeding, competition, and sale. This creates a complex epidemiological web that accelerates the transboundary risk of infectious diseases like AHS. According to the International Federation for Equestrian Sports (FEI), over 250,000 horses cross international borders annually under the Temporary Importation (TI) system.11 These extensive movements, particularly in the Arabian Gulf, Europe, and Asia, dramatically increase the risk of viral dissemination. Moreover, horses are transported between events with minimal quarantine periods, relying heavily on strict vaccination protocols. Should AHS be introduced via these routes by either asymptomatic carriers or infected midges transported in contaminated crates, the likelihood of transmission by local midge populations would increase sharply. How rapidly vector-borne pathogens can move across borders, could be seen with the emergence of bluetongue virus serotype 3 (BTV-3) in Europe: first identified in the Netherlands in September 2023, it rapidly disseminated across European countries by late 2024, including the United Kingdom.12, 13 The threat of AHS perfectly encapsulates the complexities of a One Health challenge, illustrating the intimate connections between animal health, human well-being, and environmental health. Rising global temperatures directly affect Culicoides biology, allowing expansion into formerly moderate climatic regions and increasing vector competence of local midge species. This accelerates life cycles, shortens extrinsic incubation periods (EIP) and enables midges to become infectious faster and for longer durations, creating greater opportunities for AHSV introduction and establishment. The interplay between climate change and vector dynamics fundamentally alters disease epidemiology, making areas once unsuitable for AHS transmission increasingly vulnerable. The primary environmental drivers of AHS are the competence of Culicoides midges and the presence of susceptible equids. These tiny 1–3 mm biting insects are the biological vectors transmitting the virus. Over 1000 Culicoides species exist globally, with key vectors like Culicoides imicola and C. bolinitos in Africa.14 Their lifecycle is highly sensitive to temperature and humidity, allowing their population growth under warm and moist conditions. This raises concern for AHS outbreaks similar to recent outbreaks of many serotypes of BTV in Europe, where the virus spread northward from Africa via local midge species.15 In 2020, AHSV-1 crossed into Southeast Asia, causing a devastating outbreak in Thailand and over 500 equine deaths.7 Investigations suggested introduction via infected zebras from Africa, highlighting risks from wildlife trade and poor vector control. The outbreak confirmed that Culicoides oxystoma is a competent vector in tropical climates.16, 17 Climate change is driving the northward expansion and increased activity of midge species, lengthening the transmission window and enlarging at-risk areas in Europe and the Middle East. Changing weather patterns, increased rainfall, and warmer temperatures create ideal conditions for midge proliferation, precipitating animal disease crises with severe socio-economic consequences. This highlights how environmental and climate shifts can directly drive disease emergence and spread of arboviruses, posing overarching risks to both animal and human well-being. Vaccine Prevention Strategies: Vaccination remains the most important part of disease control, but the choice presents a complex challenge, particularly for non-endemic regions like Europe and the Middle East. Currently there are three main approaches, that are relevant: The question ‘The One Health Threat of African Horse Sickness: Are Europe or the Middle East Next?’ demands serious attention—particularly as the potential spread of AHS to Europe becomes an increasingly real concern. It highlights the urgent and critical need for a unified One Health approach to managing transboundary animal diseases. This serves as a powerful reminder of our global interconnectedness and the necessity of a coordinated, cross-sectoral response. African Horse Sickness is a clear and present danger, exacerbated by intense global environmental changes. By proactively integrating expertise and resources across disciplines, investing in the development of advanced and safe vaccine technologies (especially DIVA vaccines), and implementing robust preparedness plans, Europe and the Middle East do not have a lot of time to be prepared for this emerging threat. To avoid outbreaks as seen in BTV in Europe, it is important to safeguard not only their valuable equine populations but also the livelihoods and well-being of their communities. Ultimately, addressing the climate-driven expansion of vector-borne diseases like AHS is paramount for a truly effective and sustainable One Health future. The time for a unified, anticipatory One Health response to AHS is now. Christiana Hebel: Writing – original draft; writing – review and editing. David Craig: Writing – review and editing; supervision. Piet A. van Rijn: Writing – review and editing; resources. Sunitha Joseph: Writing – review and editing; resources. Ulrich Wernery: Supervision.
Source: Equine Veterinary Journal
DOI: 10.1111/evj.70119
Language: English
Topic: Vector-Borne Animal Diseases
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W4416206552