Warm winters are associated to more intense West Nile virus circulation in southern Spain

ABSTRACT

West Nile virus (WNV) is the most widely distributed mosquito-borne flavivirus in the world. This flavivirus can infect humans causing in some cases a fatal neurological disease and birds are the main reservoir hosts. WNV is endemic in Spain, and human cases have been reported since 2004. Although different studies analyse how climatic conditions can affect the dynamics of WNV infection, very few use long-term datasets. Between 2003 and 2020 a total of 2,724 serum samples from 1,707 common coots (Fulica atra) were analysed for the presence of WNV-specific antibodies. Mean (SD) annual seroprevalence was 24.67% (0.28) but showed high year-to-year variations ranging from 5.06% (0.17) to 68.89% (0.29). Significant positive correlations (p < 0.01) were observed between seroprevalence and maximum winter temperature and mean spring temperature. The unprecedented WNV outbreak in humans in the south of Spain in 2020 was preceded by a prolonged period of escalating WNV local circulation. Given current global and local climatic trends, WNV circulation is expected to increase in the next decades. This underscores the necessity of implementing One Health approaches to reduce the risk of future WNV outbreaks in humans. Our results suggest that higher winter and spring temperatures may be used as an early warning signal of more intense WNV circulation among wildlife in Spain, and consequently highlight the need of more intense vector control and surveillance in human inhabited areas.

KEYWORDS:

• Arboviruses
• birds
• emerging infectious diseases
• long-term surveillance
• one health

Acknowledgements

To Plácido Rodríguez y Maribel Adrián for allowing us to work on their property. To Manuel Vazquez, Oscar Gonzalez, Carlos Moreno, Alberto Pastoriza and many other ringers and students that helped during the capture of the birds. Francisco Miranda, Olaya García and other technicians of the laboratory of ecophysiology (EBD) helped with the ELISA analyses. This study has been partially funded by the European Union projects, Spanish Ministry of Science projects, co-financed by FSE funds, from the Andalucian Government, CSIC's Global Health Platform (PTI Salud Global) and European Union NextGenerationEU/ PRTR funds and funded by Fundación La Caixa (See funding to references). SM is currently funded by European Union NextGenerationEU/ PRTR funds (acronym NEXTHREAT). MF is currently funded by a Ramón y Cajal contract (RYC2021- 031613-I) from the Spanish Ministry of Science and Innovation (MICINN). RGL is funded by a Sara Borrell postdoctoral contract (CD22CIII/00009) from the Instituto de Salud Carlos III. MJRL was funded by the Agencia Estatal de Investigación. PAS was funded by a FPI predoctoral fellowship from INIA.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by ‘la Caixa’ Foundation, [ARBOPREVENT (HR22-00123)]; Andalucian Government [PLEC2021-007968]; Ministerio de Ciencia e Innovación [MCIN/AEI/10.13039/5011000110333]; Spanish Ministry of Science projects [E-RTA2015-00002-CO2-01, PGC2018- 095704-B-I00, PID2020-116768RR-C21, PID2021- 123761OB-I00, PID2020-118921RJ-100/AEI/10.13039/501100011033]; FSE funds, projects [P07-RNM-02511, P11-RNM-7038]; CSIC's Global Health Platform (PTI Salud Global); European Union projects [EDEN 10284, EDENEXT (261504)] and EuroWestNile [(261391)]. Sara Borrell postdoctoral contract [(CD22CIII/00009)] from the Instituto de Salud Carlos III; Spanish Ministry of Science projects [CGL2009-11445, CGL2012-30759, CGL2015-65055-P]; Ramón y Cajal postdoctoral contract [RYC2021-031613-I].