Monitoring the epidemic of West Nile virus in equids in Spain, 2020-2021.
Abstract: The largest epidemic of West Nile virus (WNV) reported ever in Spain in both humans and equines occurred in 2020, affecting 77 humans and 139 equine herds. Here, we aimed to monitor the outbreaks detected in equid herds in Andalusia (southern Spain), the Spanish region where 89.9% of the outbreaks were reported, and to evaluate the virus circulation and risk factor associated with WNV exposure in the affected herds. The first WNV case was detected in mid-July 2020, the number of outbreaks peaked in mid-August and the last one was confirmed on 26th October 2020. WNV lineage 1 was detected in 12 clinically affected horses using real time RT-PCR. Molecular analysis evidenced high nucleotide identity with WNV sequences obtained from humans, birds and mosquitoes from Spain and Italy between 2020 and 2022. Between five and eight months after the WNV epidemic, a total of 724 equids (including 485 unvaccinated and 239 vaccinated animals) from 113 of the 125 affected herds in Andalusia were sampled. IgM and IgG antibodies against WNV were detected in 1.6% (8/485; 95%IC: 0.0-2.5) and 61.9% (300/485; 95%IC: 58.3-65.5) of the unvaccinated individuals, respectively. The seropositivity in vaccinated horses was 86.6% (207/239). The main risk factors associated with WNV exposure in unvaccinated equids were the breed (crossbreed), the location of animals in spring-summer (outside), and the presence of natural water ponds close to the surveyed herds. The high individual seroprevalence obtained in the affected herds indicates that WNV circulation was more widespread than the reported by passive surveillance during the WNV epidemic in 2020. The re-emergence of WNV in 2020 in southern Spain evidenced the needed to improve integrated surveillance systems, minimizing the impact of future cases in equids and humans in high-risk areas.
Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.
Publication Date: 2023-07-13 PubMed ID: 37481993DOI: 10.1016/j.prevetmed.2023.105975Google Scholar: Lookup
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- Journal Article
- Diagnosis
- Disease control
- Disease Diagnosis
- Disease Etiology
- Disease Management
- Disease Outbreaks
- Disease Prevalence
- Disease Surveillance
- Disease Treatment
- Epidemiology
- Equids
- Equine Health
- Horses
- Infectious Disease
- Mosquito-borne Diseases
- Public Health
- Seroprevalence
- Veterinary Medicine
- Veterinary Research
- Virus
- West Nile Virus
Summary
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This research study focuses on the tracking and analysis of a major 2020 outbreak of West Nile virus (WNV) in Spain, primarily affecting horses but also humans. The researchers aimed to understand the scope of the virus, its spread, and risk factors associated with its exposure in southern Spain.
Study Aim and Location
- The study was conducted in response to the largest recorded epidemic of West Nile virus in Spain, which took place in 2020 and affected 77 human individuals and 139 groupings of horses.
- The researchers aimed to monitor and evaluate the spread of the virus among equine populations in Andalusia, a region of southern Spain where a vast majority (89.9%) of reported outbreaks occurred.
Timeline and Analysis of Virus Spread
- The initial case of West Nile virus was detected in mid-July of 2020, with the bulk of outbreaks happening by mid-August and the final confirmed case in late October.
- Through molecular analysis (real time RT-PCR), the researchers discovered that the WNV lineage 1 was present in 12 clinically-affected horses.
- The genetic structure of the virus showed a high similarity to WNV strains found in human, bird, and mosquito populations in Spain and Italy between 2020 and 2022.
Antibody Presence and Assessment of Risk Factors
- A few months after the epidemic, 724 horses from the affected herds were sampled, revealing the presence of IgM and IgG antibodies which are indicative of WNV exposure.
- While 1.6% of the unvaccinated equines carried IgM antibodies, 61.9% of unvaccinated subjects and 86.6% of vaccinated horses were positive for IgG antibodies.
- Key risk factors for WNV exposure in unvaccinated horses included the breed (crossbreed), their location in the spring and summer months (outdoors), and nearby natural water sources.
Implications
- The significant prevalence of antibodies in the tested herds indicates that the extent of WNV spread was greater than what was reported during the outbreak, highlighting flaws in passive surveillance.
- The epidemic underscores the need for improved integrated surveillance systems to reduce the impact of future outbreaks, especially in areas of high risk for both humans and horses.
Cite This Article
APA
Gonzálvez M, Franco JJ, Barbero-Moyano J, Caballero-Gómez J, Ruano MJ, Martínez R, Cano-Terriza D, García-Bocanegra I.
(2023).
Monitoring the epidemic of West Nile virus in equids in Spain, 2020-2021.
Prev Vet Med, 217, 105975.
https://doi.org/10.1016/j.prevetmed.2023.105975 Publication
Researcher Affiliations
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain; Departamento de Sanidad Animal, Facultad de Veterinaria, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Universidad de Murcia, Murcia, Spain.
- Inmunología y Genética Aplicada, S.A. (Eurofins-Ingenasa), Madrid, Spain.
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain.
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain; Grupo de Virología Clínica y Zoonosis, Unidad de Enfermedades Infecciosas, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, Córdoba, Spain; CIBERINFEC, ISCIII CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain.
- Laboratorio Central de Veterinaria (LCV), Ministerio de Agricultura, Pesca y Alimentación, Algete, Madrid, Spain.
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain; Departamento de Sanidad Animal, Unidad de Patología Infecciosa, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain.
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain; CIBERINFEC, ISCIII CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain. Electronic address: v82cated@uco.es.
- Departamento de Sanidad Animal, Grupo de Investigación en Sanidad Animal y Zoonosis (GISAZ), UIC Zoonosis y Enfermedades Emergentes ENZOEM, Universidad de Córdoba, Córdoba, Spain; CIBERINFEC, ISCIII CIBER de Enfermedades Infecciosas, Instituto de Salud Carlos III, Madrid, Spain.
MeSH Terms
- Humans
- Animals
- Horses
- West Nile virus
- Spain / epidemiology
- West Nile Fever / epidemiology
- West Nile Fever / veterinary
- Seroepidemiologic Studies
- Antibodies, Viral
- Horse Diseases / epidemiology
Conflict of Interest Statement
Declaration of Competing Interest None of the authors of this study has a financial or personal relationship with other people or organizations that could inappropriately influence or bias the content of the paper.
Citations
This article has been cited 4 times.- Abbas I, Ahmed F, Muqaddas H, Alberti A, Varcasia A, Sedda L. Epidemiology and surveillance of West Nile virus in the Mediterranean Basin during 2010-2023: A systematic review. Curr Res Parasitol Vector Borne Dis 2025;7:100277.
- Carrasco L, Utrilla MJ, Fuentes-Romero B, Fernandez-Novo A, Martin-Maldonado B. West Nile Virus: An Update Focusing on Southern Europe. Microorganisms 2024 Dec 18;12(12).
- Castro-Scholten S, Caballero-Gómez J, Bravo-Barriga D, Llorente F, Cano-Terriza D, Jiménez-Clavero MÁ, Jiménez-Martín D, Camacho-Sillero L, García-Bocanegra I. Exposure to West Nile Virus in Wild Lagomorphs in Spanish Mediterranean Ecosystems. Zoonoses Public Health 2025 Mar;72(2):207-214.
- Cochet M, Piumi F, Gorna K, Berry N, Gonzalez G, Danckaert A, Aulner N, Blanchet O, Zientara S, Donadeu FX, Munier-Lehmann H, Richardson J, Benchoua A, Coulpier M. An equine iPSC-based phenotypic screening platform identifies pro- and anti-viral molecules against West Nile virus. Vet Res 2024 Mar 16;55(1):32.
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