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Background <p>The genus <i>Culicoides</i> comprises several vectors of the Bluetongue virus (BTV) affecting livestock and other ruminants. The historical occurrence and recent re-emergence of this disease in Galicia (NW Spain) make it essential to identify the vector species present in the region, determine the factors influencing their abundance, analyse their seasonal activity period and identify areas of highest epidemiological risk.</p> Methods <p>A total of 2009 light-trap collections targeting <i>Culicoides</i> were conducted at representative sites across Galicia between 2008 and 2012. A subset of the 2009 dataset was used to analyse species phenology and epidemiological risk. Several climatic and environmental factors were obtained from different sources to determine their relationship with the abundance of the identified potential BTV vectors through Negative Binomial Generalized Linear Models (NBGLMM).</p> Results <p>Five potential BTV vectors were identified in the region: <i>Culicoides obsoletus</i> s.l., <i>C. punctatus</i>, <i>C. newsteadi</i>, <i>C. pulicaris</i> and <i>C. imicola</i>. NBGLMM provided a good fit for the Obsoletus complex (<i>R</i><sup>2</sup>c = 0.68) and for <i>C. punctatus</i> (<i>R</i><sup>2</sup>c = 0.54). Non-linear correlations were observed between Obsoletus complex abundance and environmental variables. High temperatures 6&#xa0;months prior to the collection date were associated with a decrease in the abundance of the Obsoletus complex, whereas higher mean minimum temperatures 28&#xa0;days prior to sampling, NDVI and seasonality had a positive impact. <i>Culicoides punctatus</i> abundance was negatively correlated with higher mean maximum temperatures 6&#xa0;months before sampling, while higher mean minimum temperatures 2&#xa0;months prior to collection, altitude and Csb-type climate were positively associated. The vector activity period (VAP) averaged 23.9 ± 6.0&#xa0;weeks per year. The deterministic basic reproduction number <i>R</i><sub>0</sub> indicated a potential BTV transmission risk period of 16.5 ± 7.0&#xa0;weeks annually, whereas the Monte Carlo approach estimated a period of 14.8 ± 5.6&#xa0;weeks per year. This means a period approximately 31.0–38.1% shorter than the VAP, suggesting that periods of vector presence do not necessarily translate into sustained disease transmission potential.</p> Conclusions <p>This research provides valuable insights into the ecological determinants of BTV vectors abundance under Atlantic climate conditions. These findings are crucial for understanding disease transmission dynamics and improving vector control strategies. By integrating climatic characteristics and identifying areas of highest epidemiological risk, public health interventions and management measures can become more targeted and efficient.</p> Graphical Abstract <p></p>

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Environmental factors influencing Culicoides vectors of Bluetongue in northwestern Spain: abundance, phenology and epidemiological risk

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月28日

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  • Alejandro Polina,
  • Yasmina Martínez-Barciela,
  • Ignacio Ruiz-Arrondo,
  • Rosa Estrada,
  • Josefina Garrido

摘要

Background

The genus Culicoides comprises several vectors of the Bluetongue virus (BTV) affecting livestock and other ruminants. The historical occurrence and recent re-emergence of this disease in Galicia (NW Spain) make it essential to identify the vector species present in the region, determine the factors influencing their abundance, analyse their seasonal activity period and identify areas of highest epidemiological risk.

Methods

A total of 2009 light-trap collections targeting Culicoides were conducted at representative sites across Galicia between 2008 and 2012. A subset of the 2009 dataset was used to analyse species phenology and epidemiological risk. Several climatic and environmental factors were obtained from different sources to determine their relationship with the abundance of the identified potential BTV vectors through Negative Binomial Generalized Linear Models (NBGLMM).

Results

Five potential BTV vectors were identified in the region: Culicoides obsoletus s.l., C. punctatus, C. newsteadi, C. pulicaris and C. imicola. NBGLMM provided a good fit for the Obsoletus complex (R2c = 0.68) and for C. punctatus (R2c = 0.54). Non-linear correlations were observed between Obsoletus complex abundance and environmental variables. High temperatures 6 months prior to the collection date were associated with a decrease in the abundance of the Obsoletus complex, whereas higher mean minimum temperatures 28 days prior to sampling, NDVI and seasonality had a positive impact. Culicoides punctatus abundance was negatively correlated with higher mean maximum temperatures 6 months before sampling, while higher mean minimum temperatures 2 months prior to collection, altitude and Csb-type climate were positively associated. The vector activity period (VAP) averaged 23.9 ± 6.0 weeks per year. The deterministic basic reproduction number R0 indicated a potential BTV transmission risk period of 16.5 ± 7.0 weeks annually, whereas the Monte Carlo approach estimated a period of 14.8 ± 5.6 weeks per year. This means a period approximately 31.0–38.1% shorter than the VAP, suggesting that periods of vector presence do not necessarily translate into sustained disease transmission potential.

Conclusions

This research provides valuable insights into the ecological determinants of BTV vectors abundance under Atlantic climate conditions. These findings are crucial for understanding disease transmission dynamics and improving vector control strategies. By integrating climatic characteristics and identifying areas of highest epidemiological risk, public health interventions and management measures can become more targeted and efficient.

Graphical Abstract