Spatial patterns of West Nile virus distribution in the Volgograd region of Russia, a territory with long-existing foci

Abstract

Southern Russia remains affected by West Nile virus (WNV). In the current study, we identified the spatial determinants of WNV distribution in an area with endemic virus transmission, with special reference to the urban settings, by mapping probable points of human infection acquisition and points of virus detection in mosquitoes, ticks, birds, and mammals during 1999–2016. The suitability of thermal conditions for extrinsic virus replication was assessed based on the approach of degree-day summation and their changes were estimated by linear trend analysis. A generalized linear model was used to analyze the year-to-year variation of human cases versus thermal conditions. Environmental suitability was determined by ecological niche modelling using MaxEnt software. Human population density was used as an offset to correct for possible bias. Spatial analysis of virus detection in the environment showed significant contributions from surface temperature, altitude, and distance from water bodies. When indicators of location and mobility of the human population were included, the relative impact of factors changed, with roads becoming most important. When the points of probable human case infection were added, the percentage of leading factors changed only slightly. The urban environment significantly increased the epidemic potential of the territory and created quite favorable conditions for virus circulation. The private building sector with low-storey houses and garden plots located in the suburbs provided a connection between urban and rural transmission cycles.

Predicting Plasmodium knowlesi transmission risk across Peninsular Malaysia using machine learning-based ecological niche modeling approaches

“…Besides, decision-tree-based models such as random forest and gradient-boosted tree are popularly used in ecological niche modeling. These models have been widely applied to estimate the potential risk areas of diseases such as malaria ( Bhatt et al, 2017 ), dengue ( Liu et al, 2016 ), West Nile virus ( Shartova et al, 2022 ), scrub typhus ( Acharya et al, 2019 ), brucellosis ( Jia and Joyner, 2015 ), and Chagas disease ( Mischler et al, 2012 ) as well as to estimate the spatial distribution of the vectors of Lyme disease ( Burrows et al, 2022 ), chikungunya ( Richman et al, 2018 ), leishmaniasis ( Cunze et al, 2019 ), and malaria ( Akpan et al, 2018 ). Previous studies have demonstrated the use of boosted regression tree (BRT) to map the geographical distribution of natural reservoirs and vectors of P. knowlesi and estimated the risk of P. knowlesi infection throughout Southeast Asia ( Moyes et al, 2016 ; Shearer et al, 2016 ).…”

Indication of West Nile Virus (WNV) Lineage 2 Overwintering among Wild Birds in the Regions of Peloponnese and Western Greece

“…Wetlands are the most important ecosystems for enzootic transmission of the virus due to the presence of both resident and migratory bird as well as of competent mosquito vectors, particularly Cx. pipiens [60]. Overall, water bodies are considered to favor the activity of mosquitoes and their capacity to complete different life cycle stages [61].…”

West Nile Virus diffusion in temperate regions and climate change. A systematic review

“…WNV is primarily transmitted by mosquitoes usually of the Culex spp. Although WNV has also been recovered from ticks in Russia, ticks have an unclear role in maintaining or disseminating the virus and their role may be relevant in preserving the virus during the winter [4]. Birds (in particular, Ardeid birds such as herons and egrets) are the primary hosts, and the virus is maintained in a bird-mosquito-bird cycle.…”