On the Results of Serological Evaluation and a Necessity of Surveillance over West Nile Virus among Population in the Khabarovsk Territory

The aim of the study was to evaluate intensity of contacts of the Khabarovsk Territory population with West Nile virus (WNV) based on the results of serological screening during 2022–2023. Materials and methods . Clinical material (blood sera) of 233 residents of the Khabarovsk Territory was tested for the presence of specific antibodies to WNV. Information on retrospective manifestation of West Nile fever (WNF) between 2010 and 2023 was obtained from scientific literature and reports presented to the Rospotrebnadzor Administration in the Khabarovsk Territory by Reference Center for Monitoring the WNF Pathogen at the premises of the Volgograd Research Anti-Plague Institute of the Rospotrebnadzor. Results and discussion . Specific IgM to WNV were detected in 15 out of 233 surveyed people. Among them, 11 individuals were hospitalized in medical organizations of the Khabarovsk Territory with the diagnosis of “tick-borne rickettsiosis”, “Ixodidae tick-borne borreliosis”. Positive results for IgG antibodies were revealed in 38.2 % of the samples. With the exclusion of antigenic cross-reactions to the tick-borne encephalitis virus, the level of the immunity to the West Nile virus was 9.0 %. The results of antibody avidity index showed that 90.1 % of positive samples had IgG of low avidity (IA<50 %). The results of the research allow for assuming the presence of West Nile fever cases among the Khabarovsk Territory population. High frequency of detection of IgM (8.5 %) among patients of infectious hospitals may indicate active epidemic process. Identification of 90.1 % of low avidity IgG in samples that were positive for IgG-WNV also confirms recent contact (less than 3 months) with the agent of WNF.