West Nile Virus disease ecology in Berlin
West Nile virus (WNV) is a flavivirus that circulates between birds and mosquitoes and can also infect humans. WNV is increasingly emerging in Europe and is endemic in Berlin. WNV infection rates in mosquitoes are influenced by urban land coverage and the bird community composition. To get a better understanding of local viral amplification and geographic spread, mosquitoes will be systematically collected across the Berlin metropolitan area and drivers for virus amplification as well as areas with a higher human infection risk will be identified. The geographic spread of WNV across the greater Berlin area and areas with higher rates of viral detections will be mapped. These studies will help to localize high risk areas early and strengthen public health preparedness. The project is headed by Prof. Sandra Junglen at Charité – Universitätsmedizin Berlin as part of the DZIF research area “Emerging Infections.” Prof. Junglen is an associated partner of the DZIF.
The West Nile virus (WNV) circulates among birds and mosquitoes. Humans can also become infected through the bite of afflicted mosquitoes. Local environmental conditions can shape the extent of WNV spread within urban environments.
The project investigates WNV distribution and transmission dynamics throughout the city of Berlin. During the WNV transmission season, mosquitoes are collected in all of Berlin’s districts using a grid-based sampling system. This allows researchers to determine how frequently WNV is present in mosquitoes at different locations and to identify areas with an increased risk of infection.
During the transmission season, mosquitoes are collected at a minimum of three locations per district using traps. At each sampling site, temperature and humidity are recorded.
The species composition of the mosquitoes and the density of primary mosquito vectors are determined for each site. The collected mosquitoes are tested for WNV infection using quantitative PCR. Complete viral genomes are sequenced to investigate whether the detected WNV strains represent new introductions into Berlin or originate from ongoing local virus circulation. In addition, genetic changes in the viral genomes are mapped, and their distribution and phenotypic characteristics are investigated.
Growth analyses of different WNV variants are performed using cell lines derived from mosquitoes, birds, and humans, as well as different types of neuronal cells.
In collaboration with the DZIF Woking Group “Mosquitoes and mosquito-associated viral infections in Germany” at the Bernhard Nocht Institute for Tropical Medicine, the researchers investigate vector competence—that is, the ability of certain mosquito species to acquire a WNV variant, support its replication, and subsequently transmit it. The project data are complemented by findings from WNV surveillance in birds conducted by the Friedrich-Loeffler-Institut (FLI) and by WNV modeling studies at Heidelberg University.
Together, these data provide a solid scientific basis for understanding WNV spread in urban environments, its transmission dynamics, and the factors influencing the risk of human infection.
