West Nile virus review highlights horses as One Health sentinels

A newly published review in Pathogens makes the case that horses should remain central to Europe’s West Nile virus surveillance strategy, not just because they can develop severe neurologic disease, but because they can serve as sensitive sentinels of local transmission risk. The article, published in March 2026, examines European evidence from 2010 to October 2025 and frames equine surveillance as a practical bridge between veterinary medicine, public health, and vector control. (mdpi.com)

That message lands against a backdrop of continuing geographic change in West Nile virus activity across Europe. The review points to the virus’s progressive expansion into parts of central and northern Europe, alongside evidence that climatic suitability, vector ecology, and overwintering may be reshaping where and how transmission occurs. A separate 2026 review in Viruses also describes Europe’s 2018 outbreak as a turning point and highlights more recent autochthonous transmission in countries and regions previously seen as lower risk, reinforcing the sense that West Nile virus is no longer a problem confined to traditional Mediterranean hotspots. (mdpi.com)

The Pathogens review emphasizes several practical points for veterinary surveillance. Horses are dead-end hosts, so they don’t sustain onward transmission, but their exposure mirrors the same mosquito-bird ecology that drives spillover into people. The paper highlights equine serology as a useful indicator of local circulation and cites examples of measurable seroprevalence in affected areas, including eastern Germany and western Romania. It also argues that combining passive clinical reporting with active monitoring in horses, wild birds, and mosquitoes gives a more complete picture of risk than any single stream alone. (mdpi.com)

That fits with the broader EU surveillance architecture already in place. EFSA and ECDC jointly track West Nile virus infections in humans, equids, and birds, while animal outbreaks are reported through the Animal Disease Information System. Under EU rules, member states must notify primary animal outbreaks within 24 hours of confirmation. EFSA says the agencies’ joint reporting is part of a One Health approach, and its 2025 updates documented both human cases and equid outbreaks across multiple countries during the transmission season. (efsa.europa.eu)

The veterinary implications go beyond surveillance policy. A companion 2026 review in Veterinary Sciences on diagnosis and surveillance in horses argues that confirming infection remains challenging because molecular tests are limited by transient, low-level viremia, while serology can be complicated by cross-reactivity with other flaviviruses and by vaccination history. That means frontline veterinarians still play a key role in recognizing compatible neurologic syndromes, collecting appropriate samples, and interpreting results in epidemiologic context. (mdpi.com)

Industry and expert commentary outside the paper points in the same direction. Earlier European analyses have argued that integrated animal-human-vector surveillance is essential for timely response, even if veterinary and public health priorities don’t always align. In France, equine field surveillance networks continue to use reporting from veterinarians as part of event-based monitoring, and recent public-facing guidance notes that equine cases remain reportable while symptomatic cases have continued to appear outside long-established southern zones. (pubmed.ncbi.nlm.nih.gov)

Why it matters: For veterinary teams, this is less about a new mandate than a clearer rationale for work many are already doing. Equine West Nile surveillance can contribute to earlier local warning, inform mosquito control and pet parent advice, and strengthen communication with public health partners. It also underscores the value of good travel history, vaccination history, and regional awareness when evaluating horses with fever or neurologic signs during mosquito season. In regions where surveillance resources are limited, horses may offer a relatively practical signal of viral circulation, although the usefulness of equine surveillance can vary with vaccination uptake and case detection intensity. That last point is an inference supported by prior European surveillance literature and the new review’s discussion of cost-effectiveness and surveillance design. (mdpi.com)

What to watch: The next test of these ideas will be the 2026 European mosquito season, when EFSA and ECDC are likely to resume regular in-season updates and national systems will show whether equine, avian, and vector data are being integrated quickly enough to catch spread into newly affected areas. (efsa.europa.eu)