Meteorological patterns and the evolution of West Nile virus in an environmentally stressed Mediterranean area

Abstract

The present work investigates the increase of confirmed cases of West Nile virus and the relationship between weather-related patterns and the geographical expansion of West Nile virus in Greece, with a special focus on West Attica, Central Greece, a semi-arid, ecologically fragile Mediterranean area. Using data from the European Environment Agency, European Drought Observatory of Joint Research Centre, the pairwise relationship between surface air temperature anomalies, precipitation anomalies, soil moisture index anomalies, and the fraction of absorbed photosynthetically active radiation anomalies (fAPAR) was evaluated during summer time of 2018, a particularly intense virus outbreak. The empirical results of this study indicate that total precipitation during 2018 was extremely high, nearly 500% above the average. These conditions contributed to the increase of soil moisture index anomaly and fAPAR, creating an ideal microenvironment (wet soils and green pastures) for mosquito breeding. This phenomenon was directly associated with a drastic outbreak of West Nile virus cases in the area, compared with earlier years. Our results indicate how unusually high values of summer precipitation may have contributed (both through direct and indirect ecological channels) to the rapid spread of the West Nile virus in West Attica, causing a significant number of confirmed cases and fatalities. Climate change may bring forth other issues aside from natural disasters, including—but not limited to—virus expansion.