Distribution of the West Nile Virus vector, Culex pipiens, in mainland Portugal: A geospatial modelling study

Martinho, Júlia; Costa Osório, Hugo; Amaro, Fátima; Silva, Manuel; Marques Zé-Zé, Líbia Maria; Pereira Figueira Alves, Maria João; Nunes, Baltazar; Soares, Patricia

http://hdl.handle.net/10400.18/10623

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Authors

Marques Zé-Zé, Líbia Maria

Pereira Figueira Alves, Maria João

Nunes, Baltazar

Soares, Patricia

Abstract(s)

Background: Culex pipiens, Portugal’s most abundant mosquito, is a vector for several pathogens including the West Nile virus. Understanding its spatial distribution can contribute to vector-borne diseases control and public health planning, given Portugal’s favourable climate. National-level data on its spatial distribution, especially in relation to climatic variables is limited. We aimed to predict the suitability of Culex pipiens distribution in mainland Portugal, considering climatic factors. Methods: A maximum entropy (Maxent) model was applied, using presence records for adult and larvae of Culex pipiens mosquitoes sampled across mainland Portugal between January 2017 and October 2023, as part of the REVIVE – Vector Surveillance Network program. Adults were sampled using CDC light traps and BG-Sentinel traps between May and October at random sites and year-round at point-of-entry sites. Larvae were sampled using dippers at breeding sites. Sampling bias was corrected by filtering presence records to one per 1 km2 cell grid. Climatic data, including temperature, precipitation and elevation, were used as predictors. Results: Out of 6,859 records, 354 unique sites were obtained after filtering and cell-duplicate removal. Suitable habitats seem to be primarily in the northern and central coastal regions. Temperature was the most important predictor. Convenience sampling bias may be present. Conclusions: Most West Nile virus case reports have come from southern Portugal, but Culex pipiens’s potential distribution covers the entire mainland territory, with seemingly higher distribution in the north. West Nile vector surveillance should be a priority in all regions to accurately assess transmission risk and implement effective control measures.

Highlights: - Maxent was used to model suitable habitats for Culex pipiens in Portugal. - Culex pipiens’s suitability distribution covers the entire mainland territory. - Culex pipiens’s potential distribution is higher in the northern coast. - Region-specific strategies for WNV prevention and control are needed.

Keywords

Climate Culex Pipiens Geospatial Modelling Mosquito-Borne Diseases Surveillance West Nile Virus Mosquito Vectors Epidemiology Spatial Analysis Infecções Sistémicas e Zoonoses Portugal