West Nile Virus (WNV): One-Health and Eco-Health Global Risks

Abstract

West Nile virus (WNV) is an important zoonotic pathogen belonging to the Flaviviridae family, which is endemic in some areas and emerging in others. WNV is transmitted by blood-sucking mosquitoes of the genus Culicoides, Aedes, and Anopheles, and the infection can cause different clinical symptoms. The most common and benign illness in humans is West Nile fever (WNF), but a lethal neurological disease (WNND), related to the neuro-invasiveness of WNV lineage 2, represents the highest health risk of WNV infection. The neuro-clinical form is recognized in mammals (land and cetaceans), particularly in humans (elderly or immunosuppressed) and in horses, avian species, and wildlife animals ranging free or in a zoological setting. This review highlights the most relevant data regarding epidemiology, virology, pathogenesis and immunity, clinical signs and differential diagnosis, pathology and imaging, histopathology and gross pathology, economic impact, influence of climate change, and surveillance of WNV. Climate change has favored the wide spread of WNV in many areas of the globe and consequent One-Health and Eco-Health emergencies, influencing the health of human beings, animals, and ecosystems.

Keywords: West Nile virus (WNV); clinical signs; diagnosis; eco-health; economic impact; epidemiology; immune response; legislation; one-health; pathogenesis; pathology; surveillance.

Figure 1

Distribution of locally acquired human WNV infections in 2024 in the European Economic Area (EEA). The EEA is divided into smaller areas according to the classification known as the Nomenclature of Terrestrial Units for Statistics (NUTS), and specifically NUTS3 refers to the Regional Level, sourced from EUROSTAT 2024 (https://ec.europa.eu/eurostat/web/nuts; accessed on 1 March 2025).

Figure 2

WNV cases submitted by the relevant Veterinary Services through WAHIS in Europe. Distribution of the WNV cases in Europe, reported by the relevant Veterinary Services through WAHIS from 1 January 2020 to 1 March 2025. The number of infected animals is depicted using a color scale ranging from light pink (0–4 cases) to bright red (751–1030 cases). Symbols indicate the types of animals: light blue circles indicate wild animals, while black triangles indicate domestic animals.

Figure 3

WNV cases submitted by the relevant Veterinary Services through WAHIS in Oceania. Distribution of WNV cases in Oceania, reported by the relevant Veterinary Services through the WAHIS from 1 January 2020 to 1 March 2025. The number of infected animals is depicted using a color scale ranging from light pink (0–4 cases) to bright red (751–1030 cases). Symbols indicate the types of animals: black triangle indicates domestic animals.

Figure 4

WNV cases submitted by the relevant Veterinary Services through WAHIS in Americas. Distribution of WNV cases in the Americas, reported by the relevant Veterinary Services through WAHIS from 1 January 2020 to 1 March 2025. The number of infected animals is depicted using a color scale ranging from light pink (0–4 cases) to bright red (751–1030 cases). Symbols indicate the types of animals: light blue circles indicate wild animals, while black triangles indicate domestic animals.

Figure 5

WNV cases submitted by the relevant Veterinary Services through WAHIS in Africa and Asia. Distribution of WNV cases in Africa and Asia, reported by the relevant Veterinary Services through WAHIS from 1 January 2020 to 1 March 2025. The number of infected animals is depicted using a color scale ranging from light pink (0–4 cases) to bright red (751–1030 cases). Symbols indicate the types of animals: light blue circles indicate wild animals, while black triangles indicate domestic animals.