West Nile virus epizootic in Germany, 2018

Area of Science:

• Veterinary Medicine
• Epidemiology
• Environmental Science

Background:

• The 2018 summer in Germany was exceptionally hot and dry, creating favorable conditions for disease vectors.
• Zoonotic diseases, particularly arthropod-borne viruses, can expand their range under specific climatic conditions.

Purpose of the Study:

• To investigate the impact of favorable climatic conditions on the spread and propagation of West Nile virus (WNV) in Germany.
• To identify the WNV strain and introduction dynamics in Germany.
• To assess the implications for public health, including transfusion services and clinicians.

Main Methods:

• Phylogeographic analysis was used to trace the introduction and spread of WNV.
• Analysis of WNV strains, including genetic sequencing of the NS3 gene.
• Correlation of climatic data (temperature, precipitation) with WNV activity.

Main Results:

• WNV infections were newly detected in wild and aviary birds in Eastern and Southeastern Germany.
• The identified WNV strain belonged to the central European subclade II, with a single introduction event likely from the Czech Republic around 2016.
• High 2018 temperatures likely reduced the extrinsic incubation period in mosquitoes, increasing WNV amplification and transmission risk.

Conclusions:

• The 2018 heatwave significantly contributed to WNV expansion in Germany.
• Public health awareness regarding WNV risks in humans, especially during late summer, is crucial for blood transfusion services and clinicians.