Vol 29, No 5 (2024)

Background: West Nile fever (WNF) is an emerging infectious disease in the Krasnodar region with understudied clinical and epidemiological manifestations. The role of the urban environment in the formation of new endemic foci remains an open question.

Aim: To characterize the main clinical and epidemiological manifestations of WNF and identify potential foci locations within the city of Krasnodar, using the 2019 outbreak as an example.

Materials and methods: A retrospective analysis was conducted on 78 inpatient medical records of patients diagnosed with WNF in 2019, confirmed via enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR). Inclusion criteria required patients to have resided within Krasnodar or its suburbs for at least one month prior to symptom onset. Using the online resource Yandex.Maps, we recorded the actual residential addresses of the cases and created a map to identify potential epidemic foci within Krasnodar and adjacent areas.

Results: The 2019 WNF outbreak in Krasnodar region registered between July and September, peaking in August. The mapping of cases in Krasnodar revealed an association with urban water bodies, both natural (lakes, ponds) and artificial (reservoirs, abandoned water bodies), with a lesser degree of association with the Kuban river. In the structure of clinical forms of WNF, the meningeal and meningoencephalitic forms predominated (77.4%, Group 1), while the influenza-like form was observed in 25.6% (Group 2). There were no gender differences between the groups; the mean age was 44.7±0.51 years, with 65% being unemployed or retired. Comorbid conditions were present in 84.5% of Group 1 patients and 35.0% of Group 2 patients, with cardiovascular diseases being the most common (46.1%). Group 1 was characterized by an acute onset with febrile fever, general cerebral and meningeal symptoms, ataxia, and meningitis with moderate lymphocytic pleocytosis. In Group 2, 50% of cases began with low-grade fever, with rash (65%), lymphadenopathy (40%), hyperemia and granular pharyngeal mucosa (75%–50%), and cough (30%) being more frequently observed.

Conclusions: Mapping of potential infection sites confirmed the importance of urban water bodies and helped identify areas at risk of WNF transmission. Effective WNF prevention in urban environments requires comprehensive surveillance of water bodies, mosquito control, and monitoring of migratory birds. For timely diagnosis, PCR and ELISA testing for West Nile fever markers should be included in the comprehensive diagnostic evaluation of patients presenting with symptoms of meningitis, meningoencephalitis, or fever of unknown origin with catarrhal symptoms, rash, and lymphadenopathy during the summer-autumn period in the southern regions of Russia.

Background: Measles is a highly contagious, anthroponotic viral disease. In Russia, measles outbreaks were recorded in 2003, 2014, and 2019, with a rise in incidence noted since 2022. Catch-up vaccination of at-risk groups and revaccination of individuals previously vaccinated with a single dose continue. Determining antibody levels in the serum of vaccinated individuals and those with unknown vaccination and post-infection history remains relevant.

Aim: To present the results of a study on humoral immunity to the measles virus among healthcare workers, including those vaccinated against measles and individuals with unknown vaccination and post-infection history.

Materials and methods: An observational, single-center, cross-sectional, uncontrolled study was conducted. Inclusion criteria: employment in a healthcare organization; age over 18 years; documented history of vaccination and revaccination with a live measles vaccine completed at least three weeks before blood sampling, or unknown vaccination and post-infection status; absence of infectious disease symptoms at the time of blood sampling. The study was conducted over one month in 2024. Venous blood samples were collected, and measles virus-specific IgG antibodies (IU/ml) were determined in the serum using an enzyme-linked immunosorbent assay kit Vector-Best (Novosibirsk, Russia). The quantitative level of class G (IgG) antibodies to the measles virus was assessed. Statistical analysis was performed using StatTech v.4.1.9 software (developed by Stattech LLC, Russia).

Results: The median age of vaccinated participants (n=133) was 48 years (Q1–Q3: 41–54, max 76). In 66% of cases (88/133), antibody titers were at a protective level, with a mean antibody titer of 0.62 IU/ml (Q1–Q3: 0.07–2.52, max 5.0 IU/ml). During the evaluation of the relationship between antibody titers and the time since revaccination at the time of titer measurement, an inverse, weak correlation was observed. The mean age of individuals with unknown vaccination and post-infection history (n=40) was 63.3±6.25 years (95% CI: 61.3–65.3), with a mean antibody level of 2.17 IU/ml (95% CI: 1.47–2.81).

Conclusions: The ongoing occurrence of measles outbreaks, the presence of individuals with unknown vaccination and post-infection history, the low levels of protective post-vaccination antibodies among healthcare workers (34%; 45/133 in this study), along with the detection of protective antibody levels in all tested individuals with unknown history (100%; 40 participants), underscore the need for continued epidemiological monitoring. Timely vaccination and/or revaccination strategies are essential for maintaining population immunity.

Background: Integrative conjugative elements (ICEs) play a significant role in the dissemination of antibiotic resistance genes among Vibrio cholerae strains. However, there are currently no standardized methods for ICE typing that allow for the analysis of large genomic datasets.

Aim: To conduct a comparative analysis of ICE sequences in Vibrio cholerae strains of various origins and to develop an algorithm for their typing.

Materials and methods: The study utilized whole-genome sequencing data from 120 toxigenic (ctxAB+tcpA+) V. cholerae O1 El Tor strains obtained using the MiSeq platform (Illumina, USA) and MinION platform (Oxford Nanopore, UK), as well as data from NCBI databases (1,886 genomes) and the European Nucleotide Archive (441 strains). The software for ICE detection and typing was developed in Java (version 11.0.13) and is available at: http://antiplague.ru/ice-genotyper/.

Results: A comparative analysis of ICE elements in toxigenic V. cholerae strains was performed. An ICE typing algorithm based on gene composition was proposed. Analysis of the V. cholerae genome collection revealed three previously undescribed ICE elements, designated ICEVchRus1, ICEVchHai3, and ICEVchLaos.

Conclusions: The study identified three previously undescribed ICE elements and mapped their distribution across Russia and other regions of the world. It was established that during the cholera outbreak in Dagestan in 1994, strains containing ICEVchBan11 and ICEVchBan9 were circulating simultaneously.

Botulism is not a commonly encountered infectious disease; however, its severity, the potential use of botulinum toxin as a biological weapon, and the lack of truly effective methods and approaches for treating patients with this pathology prevent it from being regarded as a secondary concern.

Therapeutic measures for botulism, both currently applied in clinical practice and those under development, can be divided into three complementary but unequal groups in terms of volume, complexity of implementation, and effectiveness. The first group of measures aims to neutralize free botulinum neurotoxin in the patient’s body — whether in the blood, stomach, or intestines — by any available means. The objective is to prevent further toxin entry into nerve cells and, consequently, the progression of clinical signs of specific intoxication. This objective is primarily achieved through the intravenous (for rapid effect) administration of specific antitoxins — in Russia, this role is assigned to botulinum antitoxin serum. The use of immunoglobulins remains limited, and monoclonal antibodies are still under investigation.

The second group of measures, predominantly in the development phase with varying degrees of maturity, can be characterized as attempts to create drugs for intraneuronal (antidote) therapy aimed at disrupting the sequential intracellular actions of botulinum neurotoxin — from its internalization into the axonal cytoplasm via the endosomal pathway to the damage of the SNARE protein complex. These include guanidine hydrochloride, 4-aminopyridine (4-AP), 3,4-diaminopyridine (3,4-DAP), tousendanin, and other substances. However, these drugs have not progressed beyond laboratory research and isolated clinical cases with inconclusive results. The third group of therapeutic measures focuses on addressing pathological processes and effects already induced by botulinum neurotoxin at the systemic level. Without underestimating the importance of the continually evolving technology of intravenous infusion therapy for various intoxications, it should be noted that these methods primarily address the consequences rather than the cause. In this regard, some authors consider the possibility of intensive correction of homeostatic disorders through the administration of specialized fluids into the gastrointestinal tract as an addition to or alternative for standard therapy — enteral correction.

The use of enteral correction not only detoxifies the gastrointestinal tract but also restores water-electrolyte balance, acid-base homeostasis, hemorheology, microcirculation, pro- and antioxidant balance, intestinal microbiota, and gastrointestinal motility. The elimination of both the intoxication itself and, more importantly, its underlying cause, promotes the activation of reparative processes, including the restoration of neuromuscular transmission through the synthesis of new SNARE proteins.