Impact of environmental factors on the distribution patterns of nephropathia epidemica cases in western Europe.

Abstract

BACKGROUND Environmental factors, such as fluctuations of climatic conditions and land cover, play a pivotal role in driving infectious disease epidemics, particularly those originating from wildlife reservoirs. Orthohantavirus puumalaense, hosted by bank voles in Europe, is the causative agent of a form of haemorrhagic fever and renal syndrome called nephropathia epidemica. Despite two decades of consistent presence in western Europe, nephropathia epidemica outbreaks still pose challenges due to localised periodic occurrences and a lack of understanding of its environmental drivers. OBJECTIVE Our study aims to bridge this gap by investigating the specific ecological and climatic factors influencing nephropathia epidemica outbreaks in western Europe. METHODS We compiled monthly, serologically confirmed nephropathia epidemica case data obtained from public health authorities in Belgium, France, Germany, and the Netherlands for the period 2004-2012. Cases were geo-referenced to the finest available administrative unit. We selected 28 covariates, including climatic variables, land cover, tree species distributions, and human population, and implemented a Bayesian spatio-temporal model using integrated nested Laplace approximation (INLA) with zero-inflated Poisson distribution, including fixed effects and spatial, temporal, and non-structured random effects. RESULTS We identified key triggers for nephropathia epidemica outbreaks, particularly climate-mediated changes in all seasons up to two years before, favouring tree mast impacting bank vole abundance. Our findings revealed that while land cover factors mostly determine hotspots locations, climatic fluctuation patterns rather tend to modulate outbreak intensity. DISCUSSION Crucially, our model allows for the generation of yearly maps showcasing nephropathia epidemica incidence and risk factors, aiding in public health preparedness against climate change-induced disease emergence. This work represents a significant step towards developing targeted forecasting tools for Orthohantavirus puumalaense outbreaks, offering valuable insights for epidemic control strategies. https://doi.org/10.1289/EHP15457.