West Nile Virus occurrence and ecological niche modeling in wild bird species and mosquito vectors; an active surveillance program in the Peloponnese Region of Greece

Authors: SOFIA, MARINA - University Of Thessaly; GIANNAKOPOULOS, ALEXIOS - University Of Thessaly; GIANTSIS, IOANNIS - European Biological Control Laboratory (EBCL); TOULOUDI, ANTONIA - University Of Thessaly; BIRTSAS, PERIKLIS - University Of Thessaly; PAPAGEORGIOU, KONSTANTINOS - University Of Thessaly; ATHANASAKOPOULOU, ZOI - University Of Thessaly; CHATZOPOULOS, DIMITRIS - University Of Thessaly; VRIONI, GEORGIA - University Of Athens; GALAMATIS, DIMITRIOS - Hellenic Agricultural Organization – Demeter; DIAMANTOPOULOS, VASSILIS - Directorate Of Public Health; MPELLOU, SPYRIDOULA - Bioefarmoges Eleftheriou & Co Lp; PETRIDOU, EVANTHIA - Aristotle University Of Thessaloniki; KRITAS, SPYRIDON - Aristotle University Of Thessaloniki; PALLI, MATINA - Wildlife Protection & Rehabilitation Center; GEORGAKOPOULOS, GIORGOS - Wildlife Protection & Rehabilitation Center; VASSILIKI, SPYROU - University Of Thessaly; ATHANASSIOS, TSAKRIS - University Of Athens; CHASKOPOULOU, ALEXANDRA - European Biological Control Laboratory (EBCL); CHARALAMBOS, BILLINIS - University Of Thessaly

Submitted to: Microorganisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2022
Publication Date: 6/30/2022
Citation: Sofia, M., Giannakopoulos, A., Giantsis, I., Touloudi, A., Birtsas, P., Papageorgiou, K., Athanasakopoulou, Z., Chatzopoulos, D., Vrioni, G., Galamatis, D., Diamantopoulos, V., Mpellou, S., Petridou, E., Kritas, S., Palli, M., Georgakopoulos, G., Vassiliki, S., Athanassios, T., Chaskopoulou, A., Charalambos, B. 2022. West Nile Virus occurrence and ecological niche modeling in wild bird species and mosquito vectors; an active surveillance program in the Peloponnese Region of Greece. Microorganisms. 10(7),1328. https://doi.org/10.3390/microorganisms10071328.
DOI: https://doi.org/10.3390/microorganisms10071328

Interpretive Summary: West Nile virus (WNV) represents a serious burden to human and animal health because of its capacity to cause unforeseen and large epidemics. In nature the virus circulates in a sylvatic/rural cycle, between birds and ornithophilic mosquitoes particularly members of the genus Culex, and under certain environmental conditions it spills over to human settlements where it infects humans and equines causing large epidemics. Environmental parameters influence the life-cycles of the mosquito, the virus, the birds and the interactions between them. In this study we used that data from a two-year long integrated bird-mosquito surveillance network and Ecological Niche Modeling (ENM) to better understand the associations between environmental factors and WNV occurrence in wild birds and mosquito vectors. New information was produced on the role of resident and migratory bird species in WNV circulation, and a WNV habitat suitability map was created, that can be a useful tool for future surveillance programs. Through systematic surveillance and long-term studies, such as this one, we can gradually build on our understanding on the ecology of WNV which is very focal in nature; without this long-term investment it will be difficult, if not impossible, to predict and mitigate the risk of disease transmission.

Technical Abstract: West Nile Virus (WNV) is maintained in nature in a bird-mosquito cycle and human infections follow a seasonal pattern, favored by climatic conditions. Peloponnese Region, located in South-ern Greece, initiated an active WNV surveillance program for the protection of public health during 2019-2020. The project included the monitoring of avian hosts and mosquito vectors, while sampling locations were prioritized after consideration of WNV circulation in birds, mosquitos and hu-mans during previous seasons. Biological materials were collected from 493 wild birds of 25 species and 678 mosquito pools, which were molecularly screened for WNV presence. Fourteen environmental variables were associated with WNV detection in wild birds and mosquitos by using two separate MaxEnt models. Viral RNA was not detected in the target species during 2019, although in 2020, it was reported in 46 wild birds of ten species and 22 mosquito pools (Cu-lex pipiens and Aedes albopictus). Altitude and land uses were significant predictors for both models and in fact, suitable conditions for virus occurrence were identified in low altitude zones. Bird- and mosquito-based surveillance systems yielded similar results and targeted vector con-trol operations were applied in cases of increased virus activity. Human cases were not reported in Peloponnese in 2020.