EPIDEMIOLOGICAL ASPECTS OF ANTHROPOGENIC INFLUENCE TO LEPTOSPIROSIS EVOLUTION

Abstract. It has been shown that practical activity of people during the last several decades exerts significant influence not only for frequency of population’s contacts with leptospirosis foci, but also for changes of mammalian types which are reservoirs and sources of infection. The last ones in significant proportion determined etiological structure of human diseases, mechanisms of infection transmission, social and professional groups, who have highest risk to be infected, and also incidence rates and changes in clinical course of infection and its outcomes. The evolution of leptospirosis is characterized by cyclic changes of epidemiological and clinical indices

Long-term monitoring of tick-borne viral encephalitis and tick-borne borreliosis in the Komi Republic

Our study was aimed at analyzing data combining objective epidemiological, zoological and entomological research intended to determine the environmental and epidemiological patterns of tick-borne encephalitis (TBE) and Lyme borreliosis (LB) foci, as well as the role of anthropogenic factors in epidemic manifestations to improve anti-epidemic activities. Long-term data on the abundance of ticks flagged from vegetation in various districts of the Komi Republic (RK) have been analyzed. The prevalence of tick-borne encephalitis virus (TBEV) and Borrelia burgdorferi (agent of LB) in ticks picked from vegetation, humans and domestic animals in various districts of the RK was measured by using enzyme-linked immunosorbent assay and polymerase chain reaction (PCR-ELISA). In addition, the data on 1994–2017 tick-bite incidence in RK, 1970–2017 TBE incidence, and 1997–2017 LB incidence were also examined and correlated with the impact of forest transformation on the TBE incidence. The rise of tick population in the southern districts of RK and its northward expansion were noted. It is also shown that the RK territory, where tick bites are registered, expanded significantly. Mean annual tick-bite incidence rate in 2006–2017 vs. 1994–2005 timeframe was increased by 4-fold. RK regions where deforestation took place, the tick-bite incidence was increased, and the local TBE incidence elevated distinctly. In recent years, there was a rise in TBEV prevalence in ticks, collected either from vegetation or from humans and animals. In 2006–2017 and 1970–1981, mean annual TBE incidence rate increased by a 11- and 36-fold as compared to that one registered in 1982–1993. In recent years, the most severe focal TBE forms began to be recorded. In 1996–2017, the TBE mortality rate was 2.3%. The main features of LB epidemiology mimic those found in TBEV. In particular, the prevalence of Borrelia burgdorferi in ticks flagged from vegetation increased from 9.5% to 34.7% in 2010 vs. 2017, respectively. A sharp rise in LB incidence rate and profound northward shift for bacterial range, where this infection started to be registered only in recent years, were noted. Both TBE and LB demonstrated marked occupation-related pattern. The need in conducting task-oriented prophylaxis of tick-borne infections is necessitated by taking into account geographic specifics. The RK northern regions should be considered as potentially endemic, where tick bites in human population has recently begun to be reported

Abundance of <i>Ixodes persulcatus</i> ticks in Komi Republic as a function of an air temperature

The sharp rising incidence of tick-borne encephalitis (TBE) in Komi Republic at the North-east of European Russia was recorded last decades. Tick-bite incidence also was grown. Rapid rise of TBE incidence growth and Ixodidae ticks depends on a number of factors, and the impact of climate change being one of them. Ixodes persulcatus ticks is considered as a main vector of TBE in Komi. Our objective is to estimate the influence of air temperature change on the tickbite incidence and Ixodes persulcatus population in Komi. Komi Republic is located near the Polar circle where the northern frontier of Ixodes persulcatus ticks situated and we expected the growth of tick’s population. The number of Komi inhabitants seeking medical care after tick bites in 1992–2014 was considered. Gridded monthly air temperature data with grid size 0.5 degree were recalculated to temperature referred to Komi administrative units. The time series of annual number of tick victims from 1992 till 2014 and model air temperature from 1948 till 2016 for all Komi administrative units were compiled. We analyzed the data on tick-bite incidence in Komi administrative units in relation to changes in local annual average air temperature within the study area. The linear dependence of the tick-bite incidence on air temperature was established when of the tick-bite incidence is represented in logarithm form. The tick population depends not only on temperature but humidity, landcover and hosts. Described areas of Komi belong to humid climate, where precipitations exceed evaporation. Most of the Komi territory is covered by taiga with underwood, grass and bush. Hosts of the first and the major levels are represented by birds and rodents. The dependence of tick-bite incidence and temperature looks like “Malthus’s law”, but the development of population depends on temperature not on time. The exponential growth in the nearest future will ceased and the population will proceed to stable phase. Ticks population in Komi Republic is moving to the North and the air temperature determines the dynamics of population

Molecular and genetic characterization of LEPTOSPIRA spp. collection strains from the St. Petersburg Pasteur institute based on 16S rRNA gene sequencing data

Leptospirosis is a zoonotic disease found virtually worldwide. Microscopic Agglutination Test with live leptospira (MAT) is the reference method for the serological diagnosis of leptospirosis. MAT is based on assessing serum potential to agglutinate live reference serovar Leptospira maintained at a reference laboratory. At some laboratories having own collections of isolated and reference Leptospira strains applicable for serological diagnosis, those microorganisms are maintained for many years by repeated subculturing, that increases markedly a chance of strain cross-contamination. The lack of adequate quality control for reference strains may affect data of epidemiological studies. Control of Leptospira spp. reference strains purity and stability of their antigenic composition is very important for diagnosis of leptospirosis. The study objective was to compare the 16S rRNA gene nucleotide sequences of some Leptospira strains from the collection of the St. Petersburg Pasteur Institute to with relevant sequences uploaded to GenBank. In this study, 38 Leptospira strains were investigated. Nucleotide sequences of 36 strains were deposited in the international GenBank database, inconsistencies were revealed in two strains. The study found that the control Leptospira strains from the collection of the St. Petersburg Pasteur Institute had minimal dissimilarities from international control strains. The analysis of the resultant 16S rRNA sequences has shown the presence of point mutations, transitions, deletions and insertions, regardless of the strain species. The open leptospira pan-genome demonstrates high genomic variability in species due to the capability of leptospira for lateral gene transfer in order to adapt to changing environmental conditions. The massive acquisition and loss of genes give rise to an increased species diversity. The 16S rRNA gene is suitable for screening diagnostics; however, high level of the fragment similarity and close phylogenetic relationship between different species put bounds to its use in genotyping. The presence of point nucleotide mutations is most likely associated with the evolutionary mechanisms of leptospira, their ability to horizontal gene transfer and crossing-over, including ribosomal genes, but this assumption necessitates additional research. For specimen genotyping it is necessary to select alternative genes with high specificity and sufficient level of nucleotide divergence. The study shows a need for genetic analysis of collection strains in order to control the purity of cultures

Associating land cover changes with patterns of incidences of climate-sensitive infections: an example on tick-borne diseases in the Nordic area

Some of the climate-sensitive infections (CSIs) affecting humans are zoonotic vector-borne diseases, such as Lyme borreliosis (BOR) and tick-borne encephalitis (TBE), mostly linked to various species of ticks as vectors. Due to climate change, the geographical distribution of tick species, their hosts, and the prevalence of pathogens are likely to change. A recent increase in human incidences of these CSIs in the Nordic regions might indicate an expansion of the range of ticks and hosts, with vegetation changes acting as potential predictors linked to habitat suitability. In this paper, we study districts in Fennoscandia and Russia where incidences of BOR and TBE have steadily increased over the 1995–2015 period (defined as ’Well Increasing districts’). This selection is taken as a proxy for increasing the prevalence of tick-borne pathogens due to increased habitat suitability for ticks and hosts, thus simplifying the multiple factors that explain incidence variations. This approach allows vegetation types and strengths of correlation specific to the WI districts to be differentiated and compared with associations found over all districts. Land cover types and their changes found to be associated with increasing human disease incidence are described, indicating zones with potential future higher risk of these diseases. Combining vegetation cover and climate variables in regression models shows the interplay of biotic and abiotic factors linked to CSI incidences and identifies some differences between BOR and TBE. Regression model projections up until 2070 under different climate scenarios depict possible CSI progressions within the studied area and are consistent with the observed changes over the past 20 years

Typing of Uncultured Isolates of <i>Coxiella burnetii</i> and <i>Coxiella</i>-Like Microorganisms Associated with Ticks Using <i>16S</i> rRNA Gene Nucleotide Sequence Analysis

The causative agent of Q fever, the intracellular pathogen Coxiella burnetii, is found almost worldwide; many types of blood-sucking ticks that are dangerous to animals and humans are involved in the circulation of the pathogen. Using molecular-genetic methods, closely related species of microorganisms of the genus Coxiella sp. have been discovered, some of which are endo-symbionts of ticks, and some can survive in the human body, causing an infectious process. The existence of species whose genes are similar in nucleotide sequence to those of C. burnetii makes it difficult to diagnose the pathogen in arthropod vectors. The aim of this work was to consider the use of PCR and sequencing of an extended 16S rRNA gene fragment for molecular diagnostics and differentiation of C. burnetii from Coxiella-like microorganisms. Materials and methods. Individual samples of blood-sucking ticks were examined to detect bacteria of the genus Coxiella sp. applying standard PCR. For positive samples, an extended fragment of the 16S rRNA gene was obtained and examined by sequencing and multiple alignment with homologous sequences. Results and discussion. Of the 96 examined ticks collected in the Ulyanovsk Region, one was positive for the presence of C. burnetii DNA and one – for the presence of Coxiella sp. The greatest similarity for the C. burnetii isolate was noted in comparison with Western European strains, for the Coxiella-like microorganism - with closely related bacteria from ticks of the same species. Unique polymorphisms for the detected microorganisms were identified. It has been established that genus-specific primers to the 16S rRNA gene fragment are able to amplify not only bacteria of the genus Coxiella sp., but also genetically distant species. Analysis of the sequence of the extended 16S rRNA gene fragment makes it possible to differentiate C. burnetii from Coxiella-like microorganisms; some gene polymorphisms appear to have arisen through microevolution in different geographic regions. In the European part of the Russian Federation, Coxiella-like bacteria have been uncovered for the first time

Analysis of the Dynamics of Tick-Borne Encephalitis Incidence and the Number of People who Appealed to Medical Organizations about Tick Bites in the European North of Russia

In recent decades, a significant increase in the incidence of tick-borne viral encephalitis (TBVE) and the number of people attacked by ticks has been recorded in the European North of Russia.The aim of the study was to analyze the dynamics of the TBVE incidence and the number of people who appealed to medical organizations regarding tick bites in the European North of Russia.Materials and methods. We used the Form No. 2 “Information on infectious and parasitic diseases”, the results of operational seasonal monitoring of TBVE, presented by the Rospotrebnadzor Administrations of the respective territories for our study. Statistical data processing was performed using the Microsoft Excel program. Display of the results on the map was carried out in the geographic information system ESRI ArcMap.Results and discussion. Combined analysis of the data on the number of cases and TBVE incidence, the number of people who appealed to medical organizations about tick bites and the number of people seeking advice about tick bites per 100 thousand population for the Arkhangelsk Region, the Republics of Karelia and Komi and their municipal districts has been performed. The mean values and gradients of the number of cases, incidence (2010–2020), the number of people who appealed to medical organizations regarding tick bites, and the number of people seeking treatment for tick bites per 100 000 population (2002–2020) have been calculated; maps of average values and gradients constructed. The incidence and the number of cases remain at the high level, exceeding the national average, but have been declining in the last decade. The number of people who appealed to medical organizations and the appealability of the population about tick bites per 100 000 of the population remain at a consistently high level and show no downward trend. The incidence and appealability of the population due to tick bites per 100 thousand of the population is spreading in a northerly direction, covering new territories in the Arctic zone. The main driving force behind the observed epidemic situation in the European North of Russia is the natural processes of climate change

ДИАГНОСТИКА БЕССИМПТОМНОЙ ИШЕМИЧЕСКОЙ БОЛЕЗНИ СЕРДЦА У БОЛЬНЫХ, КОТОРЫМ ПРЕДСТОЯТ РЕКОНСТРУКТИВНЫЕ ОПЕРАЦИИ НА АОРТЕ И МАГИСТРАЛЬНЫХ АРТЕРИЯХ НИЖНИХ КОНЕЧНОСТЕЙ

Goal of the study: working out procedure aimed at the diagnostics of painless myocardial ischemia in the patients expecting surgery on aorta and main arteries of lower limbs. Materials and methods. 72 patients with disorders of aorta and main arteries of lower limbs were enrolled into the study. Depending on factors of risk to develop cardiac vascular disorders as per Lee score they were divided into two groups. Group 1 (n = 38) included patients who had 2 and more risk factors in the pre-operative period, Group 2 included patients (n = 34) who had less than 2 risk factors. All of the patients had holter monitoring, stress echocardiography and coronary arteriography during pre-operative period. Results. The study showed the high efficiency of Lee score of cardiac-vascular complication risks. The patients who had 2 risk factors and more had hemodynamically significant lesions of coronary bed in 97.4% which was detected by coronary arteriography. In Group 2 painless myocardial ischemia was detected almost in 1/3 of patients, which later provided certain impact in the choice of surgical treatment strategy. Conclusions. The results proved low efficiency of holter monitoring in the patients suffering from multi-focal atherosclerosis and high efficiency of stress echocardiography. The latter should be mandatory included into the examination procedure of such patients regardless of the results of Lee score; and coronary arteriography is to be performed in case of 2 risk scores and more. Detection of painless myocardial ischemia can change the plan of surgical treatment and requires amending anesthesia tactics. Цель исследования: отработка алгоритма действий, направленного на диагностику бессимптомной ишемической болезни сердца (ИБС) у больных, готовящихся к оперативному вмешательству на аорте и магистральных артериях нижних конечностей. Материалы и методы. В исследование включено 72 пациента с патологией аорты и магистральных артерий нижних конечностей. В зависимости от наличия факторов риска развития сердечно-сосудистых осложнений по Lee они были разделены на две группы. В 1-ю группу (n = 38) вошли пациенты, у которых в предоперационном периоде было определено 2 фактора риска и более, 2-ю группу составили пациенты (n = 34), у которых было менее 2 факторов риска. В предоперационном периоде всем им выполняли холтеровское мониторирование, стресс-эхокардиографию, коронарографию. Результаты. Исследование показало высокую эффективность применения шкалы риска сердечно-сосудистых осложнений по Lee. У пациентов, имевших 2 фактора риска и более, в 97,4% случаев при коронарографии были верифицированы гемодинамически значимые поражения венечного русла. Во 2-й группе атипичную ИБС удалось выявить почти у 1 /3 пациентов, что в дальнейшем также повлияло на выбор стратегии хирургического лечения. Выводы. Результаты показали низкую значимость методики холтеровского мониторирования у пациентов с мультифокальным атеросклерозом и высокую значимость стресс-эхокардиографии. Последнюю следует обязательно включать в алгоритм обследования таких больных независимо от результатов оценки риска осложнений по Lee, а коронарографию – при риске в 2 балла и более. Выявление бессимптомной формы ИБС может изменить план хирургического лечения и диктует внесение корректировок в тактику анестезии.

ACTIVITY OF THE PARASITIC INFECTIONS DEPARTMENT DURING THE GREAT PATRIOTIC WAR

ACTIVITY OF THE PARASITIC INFECTIONS DEPARTMENT DURING THE GREAT PATRIOTIC WA