The article presents data about the clinic, postmortem studies and specific diagnosis of the first registered in the Russian Federation fatal case of dengue fever that is associated with the first and only trip to Indonesia. The patient had hemorrhagic form of dengue fever with shock syndrome.

In the article there is presented the most complete to date information on the incidence of Crimean hemorrhagic fever (CHF) in endemic countries in Europe, Africa and Asia, with allowances made for the first publications in the 40-ies of XX century to 2012. According to available sources, the total number of cases of CHF in this period was 7924, out of which 2180 in the Russian Federation, 1820 in Turkey, 1554 in Bulgaria, 553 in Uzbekistan, 286 in China, 264 in Kosovo, 260 in Kazakhstan, 265 in Africa (including 180 in South Africa).

The tick-borne encephalitis virus (TBEV) is one of the most common members of the Orthoflavivirus genus, which comprises the causative agents of severe diseases in humans and animals. Due to the expanding areas of orthoflavivirus infection, its differential diagnosis is highly demanded. Commercial test kits based on inactivated TBEV may not provide reliable differentiation between flaviviruses because of serological crossover in this genus. Application of recombinant domains (sE and dIII) of the TBEV Sukhar-strain protein E as antigens in an ELISA test system allowed us to identify a wide range of antibodies specific to different TBEV strains. We tested 53 sera from human patients with confirmed TBE diagnosis (the efficacy of our test system based on sE protein was 98%) and 56 sera from patients with other orthoflavivirus infections in which no positive ones were detected using our ELISA test system, thus being indicative of its 100% specificity. We also tested mouse and rabbit sera containing antibodies specific to 17 TBEV strains belonging to different subtypes; this assay exhibited high efficacy and differentiation ability in detecting antibodies against TBEV from other orthoflaviviruses such as Omsk hemorrhagic fever, Powassan, yellow fever, dengue, West Nile, Zika, and Japanese encephalitis viruses.

A case of Tick-borne spotted fever in a child after a visit to an endemic region, the Republic of Crimea, is described. The disease caused difficulty in terms of clinical diagnosis, which led to the delayed prescription of specific therapy with doxycycline. The diagnosis of Тick-borne spotted fever was made on the basis of detectingR. conoriiDNA in a washout with primary affect. In the course of the disease, IgM class antibodies were detected during serological analysis of paired serum.

The family Phenuiviridae, part of the order Hareavirales, includes arboviruses and arthropod-associated viruses, with sandflies, mosquitoes, and ticks as primary vectors. Historically, only sandfly/mosquito-borne phenuiviruses were associated with human diseases, but the emergence of severe fever with thrombocytopenia syndrome (SFTS) has highlighted the potential of tick-borne phenuiviruses as human pathogens. Recent discoveries of new arthropod-associated viruses, some of which remain unclassified, underscore the need for sensitive detection and differentiation methods, particularly in regions where these viruses may co-circulate. This study aimed to develop real-time PCR test systems for identifying and differentiating unclassified viruses within the Phenuiviridae family. In this study, tick suspensions containing phenuiviruses, previously obtained during the screening of ticks from various regions of Russia using pan-phenuivirus primers, were used. Specific primers and probes were designed to differentiate five Phenuiviridae viruses of genera Uukuvirus, Ixovirus, Phlebovirus and one unclassified phenuivirus, and their analytical sensitivity and specificity were evaluated. These PCR-based tools provide a robust method for detecting and classifying uncharacterized phenuiviruses, contributing to improved surveillance and understanding their potential epidemiological and epizootological impacts.

Sera of inhabitants of the European part of Russia, collected in 2010-2013 were studied with the use of ELISA and neutralization test. Antibodies to West Nile virus were detected in 19.6% of cases in the Astrakhan region, 4.5% - in the Krasnodar region, 0.9% - in the Saratov region and 5.4% - in the Stavropol region. The coincidence of the results of the examination of sera in ELISA-IgG and neutralization test accounted of 80.7% in the Astrakhan region, 72.2% - in the Krasnodar region and 69.2% - in the Saratov region. The presented results correlate with the incidence and duration of known epidemiological activity of West Nile fever in the territories of these regions. Analysis of our data, as well as statistics of the morbidity rate of West Nile fever in the Volgograd and Rostov regions and Dagestan confirm endemic and expanding foci of this infection in the southern regions of Russia, currently including Astrakhan, Volgograd, Rostov, Saratov, Krasnodar and Stavropol regions and Dagestan. The most active and stable foci are located on the territory of Astrakhan, Volgograd and Rostov regions.