Linking a compartment model for West Nile virus with a flight simulator for vector mosquitoes

Antje Kerkow,Ralf Wieland,Jörn M Gethmann,Franz Hölker,Hartmut H.K Lentz

doi:10.1016/j.ecolmodel.2021.109840

Abstract

Compartmental SIR and SEIR models have become the state of the art tools to study infection cycles of arthropod-borne viruses such as West Nile virus in specific areas. In 2018, the virus was detected for the first time in Germany, and incidents have been reported in humans, birds, and horses.The aim of the work presented here was to provide a tool for estimating West Nile virus infection scenarios, local hotspots and dispersal routes following its introduction into new locations through the movements of mosquitoes. For this purpose, we adapted a SEIR model for West Nile virus to the conditions in Germany (temperatures, geographical latitude, bird and mosquito species densities) and the characteristic transmission and life trait parameter of a possible host bird and vector mosquito species. We further extended it by a spatial component: an agent-based flight simulator for vector mosquitoes. It demonstrates how the female mosquitoes move within the landscape due to habitat structures and wind conditions and about how many of them leave the region in the different cardinal directions.We applied the space–time coupled model with a daily temporal and spatial resolution of 100m × 100m to the Eurasian magpie (Pica pica) and the Asian bush mosquito (Aedes japonicus japonicus). Both species are widely distributed in Germany and discussed as important hosts and vectors, respectively. We also applied the model to three study regions in Germany, each representing slightly different climatic conditions and containing significantly different pattern of suitable habitats for the mosquito species.

Highlights

As it is known that Ae. j. japonicus spreads passively to a large extent, especially along roads (Egizi et al, 2016), we suggest that the exceptional dispersal rates exceeding 2 km/year are due to this cause
We introduce the first compartment model for West Nile virus, which simulates the abundance and movements of a vector mosquito species in a spatial extension and helps to estimate where virus hotspots could be located and towards which direction the virus is likely to be carried from a region by active flights of the mosquitoes
The flight simulator is an agent-based model built on a habitat map for the mosquito species being invasive in Germany, data on local temperature and wind conditions, and studies on the flight behaviour of this and other mosquito species

Summary

Introduction

West Nile virus (WNV) is an arthropod borne pathogen maintained in enzootic transmission cycles between birds (amplifying hosts) and ornithophilic mosquitoes (vectors) (Chancey et al, 2015; Marini et al, 2018). Horses and other mammals may be dead-end hosts. Germany was affected for the first time with 12 confirmed infections in birds and 2 in horses (Ziegler et al, 2019; Kampen et al, 2020; Ziegler et al, 2020). In the following years, repeated cases occurred in the affected regions in Germany and beyond, indicating that the virus hibernates in local mosquito populations (Kampen et al, 2020; Ziegler et al, 2020; Neupert, 2020; Pietsch et al, 2020)

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