Peculiarities of Epidemiological Situation on the West Nile Fever in the Russian Federation in 2020 and Forecast for Its Development in 2021

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.

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

Shartova

Mironova

Zelikhina

et al. 2022

PLoS Negl Trop Dis

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West Nile Fever: Results of Monitoring over the Causative Agent in the Russian Federation in 2021, the Incidence Forecast for 2022

Putintseva¹,

Удовиченко²,

Никитин³

et al. 2022

Problemy Osobo Opasnykh Infektsii

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The epidemiological situation on West Nile fever (WNF) in Russia in 2021 was characterized by an increase in the incidence relative to 2020 (more than 6-fold increase). The peculiarities of the WNF epidemic process have been determined: the territorial distribution of cases (75 % – in the constituent entities of the Central Federal District), the expansion of the causative agent’s areal with the involvement of new territories (official registration of cases in Moscow and the Tula Region for the first time ever), the early end of the epidemic season. An increase in the proportion of neuroinvasive forms, an increase in the share of male patients and the age group of 30–39 years, a decrease in the proportion of the population in contact with the pathogen in natural places of mass recreation were observed in the incidence structure. According to the results of the monitoring studies carried out by the Reference Center, intensive circulation of the pathogen was established on the territory of the Central Federal District, Southern Federal District, and the North Caucasian Federal District. The low reported incidence was due to insufficient detection of WNF patients. The results of moleculargenetic study showed that in the European part of Russia, WNV lineage 2 circulated in both epizootic and epidemic cycles, lineage 2 in the south of Western Siberia (Omsk Region) and lineage 4 in the Volgograd Region – in the epizootic cycle only. Phylogenetic analysis revealed that strains isolated from the Astrakhan, Volgograd, Rostov, Voronezh Regions and the Republic of Dagestan in 2021 belong to the genovariant of WNV lineage 2 not registered in Russia previously. The topology of the phylogenetic tree indicates the possible African origin of the isolates, probably imported into Russia by migratory birds across the coast of the Caspian Sea. In the Volgograd Region, WNV of both the entrenched clade of lineage 2 (since 2007) and new genovariant circulated. The specialists of the Reference Center developed a forecast of WNF epidemiological situation development in the Volgograd Region in 2022 on the basis of the neural network modeling technique, according to which an increase in the incidence is expected, comparable to that in 2010 and 2012. Based on the climate projections, an increase in the incidence is possible in all Federal Districts of the European part of Russia, the southern territories of the Urals, Western Siberia, and the Far East.

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Evaluation of the diagnostic efficacy of a reagent kit for <i>in vitro</i> diagnosis of West Nile fever using reverse transcription polymerase chain reaction with fluorescent probe-based detection

Prokhvatilova

Ткаченко

Baturin

et al. 2023

Biological Products. Prevention, Diagnosis, Treatment

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West Nile fever is a vector-borne zoonotic arbovirus infection with natural foci. Its clinical course is similar to that of acute febrile syndrome, and severe cases may result in neuroinvasive disease. Several genetic lineages (1, 2, and 4) of the West Nile virus (WNV) with different pathogenicity for humans are circulating in the Russian Federation. Therefore, it is an urgent task to develop a diagnostic reagent kit for differentiating between WNV genetic lineages and to implement the kit in clinical laboratory practice.The aim of the study was to conduct technical and clinical tests and evaluate the quality, efficacy, and safety of the Ampligen-WNV-genotype-1/2/4 diagnostic reagent kit for detecting WNV RNA and differentiating between WNV genetic lineages 1, 2, and 4 by reverse transcription polymerase chain reaction (RT-PCR) with fluorescent probe-based detection.Materials and methods. The authors determined the diagnostic sensitivity and specificity of the Ampligen-WNV-genotype-1/2/4 reagent kit (Volgograd Research Institute for Plague Control, Russia) by real-time RT-PCR with 216 clinical samples and 204 biological samples. Sanger sequencing was used as a reference method. Statistical analysis of clinical test results was carried out in accordance with the Russian national standard for clinical laboratory tests (GOST R 53022.3-2008).Results. When tested with the Ampligen-WNV-genotype-1/2/4 reagent kit, real-time RT-PCR demonstrated the analytical sensitivity of 1×104 GEq/mL for the detection of WNV cDNA of genetic lineages 1, 2, and 4. The assessment of its analytical specificity showed no positive results for cDNA samples of heterologous viruses at a concentration of 1×106 GEq/mL. The diagnostic sensitivity with the reagent kit was at least 98.5%, and the diagnostic specificity was at least 99%, with 90% confidence levels for both parameters.Conclusions. The Ampligen-WNV-genotype-1/2/4 reagent kit can be recommended for use in clinical laboratory diagnostics to detect WNV RNA and differentiate between WNV genetic lineages 1, 2, and 4.

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Peculiarities of Epidemiological Situation on the West Nile Fever in the Russian Federation in 2020 and Forecast for Its Development in 2021

Cited by 6 publications

References 6 publications

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

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

West Nile Fever: Results of Monitoring over the Causative Agent in the Russian Federation in 2021, the Incidence Forecast for 2022

Evaluation of the diagnostic efficacy of a reagent kit for <i>in vitro</i> diagnosis of West Nile fever using reverse transcription polymerase chain reaction with fluorescent probe-based detection

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