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Infectious diseases (London, England)2024; 56(9); 743-758; doi: 10.1080/23744235.2024.2348633

The key role of Spain in the traffic of West Nile virus lineage 1 strains between Europe and Africa.

Abstract: West Nile Virus (WNV) is a zoonotic arbovirus worldwide spread. Seasonal WNV outbreaks occur in the Mediterranean basin since the late 1990's with ever-increasing incidence. In Southern Spain WNV is endemic, as disease foci - caused by WNV lineage 1 (WNV-L1) strains - occur every year. On the contrary, WNV-L2 is the dominant lineage in Europe, so most European WNV sequences available belong to this lineage, WNV-L1 sequences being still scarce. Unassigned: To fill this gap, this study reports the genetic characterisation of 27 newly described WNV-L1 strains, involved in outbreaks affecting wild birds and horses during the last decade in South-Western Spain. Unassigned: All strains except one belong to the Western Mediterranean-1 sub-cluster (WMed-1), related phylogenetically to Italian, French, Portuguese, Moroccan and, remarkably, Senegalese strains. This sub-cluster persisted, spread and evolved into three distinguishable WMed-1 phylogenetic groups that co-circulated, notably, in the same province (Cádiz). They displayed different behaviours: from long-term persistence and rapid spread to neighbouring regions within Spain, to long-distance spread to different countries, including transcontinental spread to Africa. Among the different introductions of WNV in Spain revealed in this study, some of them succeeded to get established, some extinguished from the territory shortly afterwards. Furthermore, Spain's southernmost province, Cádiz, constitutes a hotspot for virus incursion. Unassigned: Southern Spain seems a likely scenario for emergence of exotic pathogens of African origin. Therefore, circulation of diverse WNV-L1 variants in Spain prompts for an extensive surveillance under a One Health approach.
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Publication Date: 2024-06-05 PubMed ID: 38836293DOI: 10.1080/23744235.2024.2348633Google Scholar: Lookup
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  • Journal Article

Summary

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Overview

  • This research examines the role of Spain, particularly southern Spain, in the transmission and evolution of West Nile virus lineage 1 (WNV-L1) strains between Europe and Africa.
  • The study provides genetic characterization of newly identified WNV-L1 strains that have caused outbreaks in wild birds and horses in Southwestern Spain over the last decade, highlighting Spain as a key hub in the virus’s spread and persistence.

Background

  • West Nile Virus (WNV) is a zoonotic arbovirus that circulates worldwide and causes seasonal outbreaks, especially in the Mediterranean basin since the late 1990s.
  • Two main lineages of WNV are relevant: lineage 1 (WNV-L1) and lineage 2 (WNV-L2).
  • While WNV-L2 is the dominant strain across Europe, Spain is notable for endemic disease caused by WNV-L1 strains.
  • Most European WNV sequences available are WNV-L2, making WNV-L1 sequences rare and understudied.

Study Objectives

  • To fill the gap in knowledge about WNV-L1 circulation in Europe, particularly Spain.
  • To genetically characterize 27 newly described WNV-L1 strains involved in outbreaks in wild birds and horses over the previous decade in Southwestern Spain.
  • To understand the phylogenetic relationships and epidemiological dynamics of WNV-L1 strains circulating in Spain.

Methods and Findings

  • Genetic sequencing and phylogenetic analysis were performed on 27 WNV-L1 strains isolated from outbreaks.
  • All but one strain belonged to the Western Mediterranean-1 sub-cluster (WMed-1), linking Spanish strains phylogenetically to strains from Italy, France, Portugal, Morocco, and significantly, Senegal in Africa.
  • The WMed-1 sub-cluster evolved into three distinct phylogenetic groups, which surprisingly co-circulated in the same province of Cádiz in Southern Spain.
  • Different groups exhibited varied epidemiological behaviors including:
    • Long-term persistence in Spain with rapid spread to neighboring regions.
    • Long-distance spread to different European countries.
    • Transcontinental spread to African countries.
  • Several introductions of WNV into Spain were identified, with some strains establishing successfully and others disappearing soon after introduction.
  • The province of Cádiz in Southern Spain emerged as a critical hotspot for virus introduction and circulation, acting as a gateway for virus movement between Europe and Africa.

Significance and Conclusions

  • Southern Spain serves as a key geographic and ecological bridge for WNV-L1 lineage circulation between Europe and Africa.
  • The genetic diversity and co-circulation of multiple WNV-L1 variants in Spain reflect ongoing viral evolution and complex epidemiological patterns.
  • Spain’s strategic location suggests it is a likely scenario for the emergence of exotic viruses of African origin, beyond just WNV.
  • The authors highlight the need for continuous and extensive WNV surveillance in this region using a One Health approach that integrates human, animal, and environmental health monitoring.
  • Improved understanding of WNV-L1 dynamics can inform prevention and control strategies to reduce the impact of outbreaks on animal and potentially human health.

Cite This Article

APA
Aguilera-Sepúlveda P, Cano-Gómez C, Villalba R, Borges V, Agüero M, Bravo-Barriga D, Frontera E, Jiménez-Clavero MÁ, Fernández-Pinero J. (2024). The key role of Spain in the traffic of West Nile virus lineage 1 strains between Europe and Africa. Infect Dis (Lond), 56(9), 743-758. https://doi.org/10.1080/23744235.2024.2348633

Publication

Infectious diseases (London, England)
ISSN: 2374-4243
NlmUniqueID: 101650235
Country: England
Language: English
Volume: 56
Issue: 9
Pages: 743-758

Researcher Affiliations

Aguilera-Sepúlveda, Pilar
  • Centro de Investigación en Sanidad Animal (CISA-INIA), CSIC, Valdeolmos, Spain.
Cano-Gómez, Cristina
  • Centro de Investigación en Sanidad Animal (CISA-INIA), CSIC, Valdeolmos, Spain.
Villalba, Rubén
  • Laboratorio Central de Veterinaria (LCV), Ministry of Agriculture, Fisheries and Food (MAPA), Algete, Spain.
Borges, Vítor
  • Genomics and Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA), Lisbon, Portugal.
Agüero, Montserrat
  • Laboratorio Central de Veterinaria (LCV), Ministry of Agriculture, Fisheries and Food (MAPA), Algete, Spain.
Bravo-Barriga, Daniel
  • Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain.
Frontera, Eva
  • Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain.
Jiménez-Clavero, Miguel Ángel
  • Centro de Investigación en Sanidad Animal (CISA-INIA), CSIC, Valdeolmos, Spain.
  • CIBER of Epidemiology and Public Health (CIBERESP), Madrid, Spain.
Fernández-Pinero, Jovita
  • Centro de Investigación en Sanidad Animal (CISA-INIA), CSIC, Valdeolmos, Spain.

MeSH Terms

  • West Nile virus / genetics
  • West Nile virus / classification
  • West Nile virus / isolation & purification
  • West Nile Fever / epidemiology
  • West Nile Fever / virology
  • West Nile Fever / transmission
  • Animals
  • Spain / epidemiology
  • Phylogeny
  • Birds / virology
  • Bird Diseases / virology
  • Bird Diseases / epidemiology
  • Horses / virology
  • Europe / epidemiology
  • Disease Outbreaks
  • Africa / epidemiology
  • Horse Diseases / virology
  • Horse Diseases / epidemiology
  • Humans
  • Animals, Wild / virology

Citations

This article has been cited 10 times.
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