A model for the assessment of bluetongue virus serotype 1 persistence in Spain

PLoS One. 2020 Apr 30;15(4):e0232534. doi: 10.1371/journal.pone.0232534. eCollection 2020.

Abstract

Bluetongue virus (BTV) is an arbovirus of ruminants that has been circulating in Europe continuously for more than two decades and has become endemic in some countries such as Spain. Spain is ideal for BTV epidemiological studies since BTV outbreaks from different sources and serotypes have occurred continuously there since 2000; BTV-1 has been reported there from 2007 to 2017. Here we develop a model for BTV-1 endemic scenario to estimate the risk of an area becoming endemic, as well as to identify the most influential factors for BTV-1 persistence. We created abundance maps at 1-km2 spatial resolution for the main vectors in Spain, Culicoides imicola and Obsoletus and Pulicaris complexes, by combining environmental satellite data with occurrence models and a random forest machine learning algorithm. The endemic model included vector abundance and host-related variables (farm density). The three most relevant variables in the endemic model were the abundance of C. imicola and Obsoletus complex and density of goat farms (AUC 0.86); this model suggests that BTV-1 is more likely to become endemic in central and southwestern regions of Spain. It only requires host- and vector-related variables to identify areas at greater risk of becoming endemic for bluetongue. Our results highlight the importance of suitable Culicoides spp. prediction maps for bluetongue epidemiological studies and decision-making about control and eradication measures.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bluetongue / epidemiology
  • Bluetongue / prevention & control*
  • Bluetongue / transmission
  • Bluetongue / virology
  • Bluetongue virus / pathogenicity*
  • Ceratopogonidae / virology*
  • Decision Support Techniques*
  • Endemic Diseases / prevention & control*
  • Endemic Diseases / veterinary
  • Epidemiological Monitoring / veterinary
  • Geography
  • Insect Vectors / virology*
  • Insecticides
  • Models, Statistical
  • Probability
  • Serogroup
  • Sheep
  • Spain / epidemiology
  • Spatial Analysis

Substances

  • Insecticides

Grants and funding

This study was funded by the H2020 EU project ‘Understanding pathogen, livestock, environment interactions involving bluetongue’ (project No: 727393-2). CA-V is the recipient of a Spanish Government-funded PhD fellowship for the Training of Future Scholars (FPU) given by the Spanish Ministry of Science, Innovation and Universities.