Design characteristics of road embankments made of sandy soils

Sandy soils are widespread all over the world, including in Uzbekistan, and they are widely used in the construction of highways. Therefore, several regulatory documents have been developed that normalize their design characteristics. However, in the existing regulatory documents, the design characteristics of sandy soils of road embankments of highways used in the design of road coverings (modulus of elasticity E, angle of internal friction φ, specific adhesion C) are not normalized depending on the degree of compaction, calculated humidity and the content of dusty and clay particles in such soils. To solve these problems, special laboratory and field studies were conducted, the results of which are given in this article

The state of specific immunity of population of the Republic of Tajikistan to measles, rubella, poliomyelitis viruses

Relevance. To achieve the goals of measles and rubella elimination and poliomyelitis eradication programs, immunization coverage of at least 95% of the target population is required. Objective data on the state of specific herd immunity are provided only by the results of serosurveys. In the Republic of Tajikistan, such monitoring is not carried out regularly. Therefore, the purpose of the study was to assess the actual state of the specific herd immunity to measles, rubella, and poliomyelitis viruses. Materials and methods. The blood sera of 563 children and adults collected in 7 cities and 13 districts of Tajikistan in 2020 were investigated. The level of antibodies (ABs) to measles and rubella viruses was determined using enzyme immunoassay. Test systems VectoKor-IgG (VECTOR-BEST, Russia) and Ecolab, Russia were used to determine ABs to measles and rubella virus, respectively. Neutralizing antibodies (nABs) to the 3 types of poliovirus (PV) were determined in 359 sera using a neutralization reaction with Sabin strains of types 1, 2, 3. Results. The conducted serosurvey showed the level of the specific herd immunity to rubella to be 87.9% in total population, including 86.2% in children, 93.1% in adolescents, and 93.5% and adults, that is sufficient to prevent transmission of the rubella virus. The proportion of individuals seropositive to measles was 54.5%, which is not enough to prevent sustained secondary transmission of infection and the resumption of circulation of the endemic strain of measles virus. The children under 15 years of age should be considered a population at risk of the infection, since children accounted for 38% among seronegative individuals. In general, less than 95% of the examined patients had nABs to PV: 94.4% to PV1, 86.1% to PV2, 83.6% to PV3; 3.3% did not have antibodies to all three types of PV. The level of herd immunity varied in the examined groups depending on the vaccination schedule and the composition of the poliovirus vaccines used: nABs to PV2 had 59.6% of children born during the period when vaccines containing PV2 were not used, and 85.7% of children born after the introduction of trivalent IPV. Deficiency in immunity to PV2 was the cause of a polio outbreak in 2021 caused by circulating vaccine-derived PV type 2. Conclusion. A high level of humoral immunity to the rubella virus was determined. Shortcomings of routine immunization against measles and polio associated with insufficient coverage and lack of IPV have been identified. Conducting regular serological monitoring in the Republic of Tajikistan is advisable to obtain objective information about the level of herd immunity, identify vulnerable groups of the population, and plan additional immunization activities

Patterns in the development of collective immunity to SARS-CoV-2 during the COVID-19 pandemic

The ongoing coronavirus disease (COVID-19) pandemic over the past three years has caused close attention to the problem of herd immunity, which is understood as: "resistance to the spread of a contagious disease within a population or herd". Collective immunity is formed both as a result of infection (natural spread of the pathogen in a population of susceptible individuals) and as a result of the use of specific vaccines. During the COVID-19 pandemic, both mechanisms for the formation of collective immunity were realized. In the first wave, there was a natural formation of collective immunity to the virus following recoveries from COVID-19 caused by pandemic spread of SARS-CoV-2. Starting from December 2020, the widespread use of specific vaccines against SARS-CoV-2 began in the USA, Great Britain, China, Russia, and a number of other countries. This launched the process of post-vaccination collective immunity formation; its features have depended on the vaccine types implemented. Currently, in those countries where vaccination and revaccination of recovered patients is widely carried out, immunity is "hybrid" in nature. Several commonalities should be noted in the pandemic experience: a somewhat regular, periodic (wavelike) nature of the COVID-19 epidemic process; changes in pathogen genetics in variants in all countries; and expansive mass vaccination programs in many populations. From these, we can draw some conclusions about the general trend for all countries in the formation of collective immunity during the pandemic: At the beginning of the pandemic in 2020, overall population seroprevalence did not exceed 20%. Other findings were: the highest seroprevalence rates were noted in the children's age group; pronounced regional differences were revealed; and the highest indicators were noted among medical workers. Collective immunity developed as a result of infection or illness, and in the majority of seropositive volunteers, it was represented by antibodies to both antigens. At the height of the pandemic in the summer of 2021, population seroprevalence reached 50%. This was due to both a significant number of convalescents and the start of mass vaccination campaigns. In all countries, specific differences in seroprevalence (by age, region, profession) leveled out, leading to more uniformity. During this period, the formation of "hybrid" immunity is clearly prominent, and the proportion of individuals with antibodies to RBD alone increased (due to vaccination with vector vaccines).  Later, mass vaccination, as well as involvement of most of the population in the epidemic process due to the emergence of the highly contagious Omicron strain, raised the level of collective immunity to 80-90%. This led to a sharp decrease in COVID-19 incidence in the second half of 2022 in all countries participating in the study. In the later stages of the pandemic (2022-2023), almost 90% of seropositive volunteers had hybrid immunity, reflected as antibodies to both antigens (Nc, RBD)

Achievement of maximal SARS-CoV-2 collective immunity among the Tajik population by March 2022

Despite all efforts of the world community, the COVID-19 pandemic remains one of the main epidemiological challenges of our time. Even with its widespread distribution, the infection may have certain local features due to social, geographic, and climatic factors. Objective: to study collective immunity to SARS-CoV-2 in the population of the Republic of Tajikistan.A cross-sectional, randomized study of herd immunity was carried out according to a program developed by Rospotrebnadzor and the St. Petersburg Pasteur Institute, taking into account WHO recommendations. The ethics committees of the corresponding entities approved the study: Tajik Ministry of Health and Social Protection; and the St. Petersburg Pasteur Institute (Russia). Based on questionnaire results, 4,022 people were selected, representing 0.15% (95% CI: 0.14-0.15) of the total population randomized by age and region. In subsequent laboratory analysis, 3682 people took part. The distribution and quantitative content of antibodies (Abs) to viral nucleocapsid (N Ag) and receptor binding domain (RBD Ag) were determined by ELISA. When questioned, a history of SARS-CoV-2 vaccination was indicated by 69.7% (95% CI: 68.2-71.2) of the volunteer cohort. Vector vaccines were most frequently used (50.6%; 95% CI: 48.7-52.5), with whole-virion inactivated preparations in second place (23.0%: 95% CI: 21.4-26.6) and mRNA vaccines in third place (21.0%; 95% CI:19.4-22.6).The cohort (n = 3682) featured 27.5% men and 72.5% women. The overall seroprevalence was 98.5% (95% CI: 97.7-99.2) in men and 99.4% (95% CI: 99.0-99.6) in women (differences statistically insignificant). Overall seroprevalence in the cohort was 99.2% (95% CI: 98.8-99.4) and ranged from 97.2 to 100% in certain subgroups. Asymptomatic seropositivity in the whole cohort was 98.4% (95% CI: 97.6-99.1). As a result of a mandatory vaccination program introduced in Tajikistan under a COVID-19 Emergency Project, the level of herd immunity among vaccinated individuals reached 99.5% (95% CI: 99.1-99.7), which is similar to the level reached in the cohort as a whole.The epidemic situation that developed in Tajikistan by mid-March 2022 was characterized by an almost absolute level of herd immunity, as evidenced by an absence of detected overt COVID-19 cases since the end of February (2022)

Assessment of the results of water use and productivity in the pilot sites of the Water Productivity Improvement Project. In Russian

In Rakhimov, S.; Mamatov, S.; Begimov, I.; Shirokova, Y.; Glovatzkiy, O.; Ikramov, R.; Ismagilov, K.; Ikramova, M.; Abirov, A.; Taganova, G.; Ananeva, N. (Eds.). Collection of scientific chapters dedicated to the 85th anniversary of the SANIIRI Irrigation Research Institute (1925-2010): SANNIRI on its way to integrated water resources management. Tashkent, Uzbekistan: Scientific Information Center of Interstate Commission for Water Coordination (SANIIRI); Tashkent, Uzbekistan: Scientific Information Center of the Interstate Commission for Water Coordination in Central Asia (SIC-ICWC

MORPHOLOGICAL AND MOLECULAR IDENTIFICATION OF SOME SPECIES OF NEMATODE OF THE FAMILY PROTOSTRONGYLIDAE LEIPER, 1926

Objective of research. The purpose of this research is to carry out morphological and molecular genetic identification and to determine phylogenetic relationship among Protostrongylidae species.Materials and methods. Helminthological material was collected from domestic hollowhorned ruminants and land mollusks in different areas of Uzbekistan. The morphology of protostrongylids was studied using the methods of Boev (1975) and Anderson (1978). The firststage larvae were investigated by examination of fecal samples from animals taking into account remarkable morphological features of larvae without dorsal cuticular thorn at the tail point (for Protostrongylinae) and with thorn (for Muelleriinae, Varestrongylinae et al.] as well as length, tail form and body size of larvae. To study the morphology of the third-stage protostrongylid larvae, the feet of infected mollusks X. candaсharica were separated and placed into the artificial gastric juice. Nucleotide sequences ITS-2 regions of species Protostrongylus rufescens, P. shiozawai, Ortostrongylus macrotis, Cystocaulus ocreatus and Umingmakstrongylus pallikuukensis were used to study phylogenetic relations between protostrongylids. The phylogenetic analysis was conducted using the software Clustal X 2.0.Results and discussion. Based on morphological and molecular examinations, five species of protostrongylid nematodes: Protostrongylus rufescens, P. hobmaieri, Protostrongylus sp., Spiculocaulus leuckarti and Cystocaulus ocreatus were found in hollow-horned ruminants. The morphological and molecular-genetic analysis of detected nematodes enables precise identification of species and spatial distribution of endemic protostrongylids

MORPHOLOGICAL AND MOLECULAR CHARACTERISTICS OF SOME NEMATODE SPECIES OF THE FAMILY PROTOSTRONGYLIDAE LEIPER, 1926

Objective of research: conducting morphological and molecular-genetic identification and studying phylogenetic relations between protostrongylids. Materials and methods:  helminthological material was  collected from  wild  (Capra sibirica, C. falconeri, Ovis vignei and O. ammon) and domestic hollow horned  ruminants (C. hircus and O. aries), and land mollusks of the family Xeropicta in the piedmont and mountain area of Uzbekisan. The morphology of protostrongylids was studied using the  methods of Boev (1975) and Anderson (1978). To identify the nematode type we used temporary preparations treated with glycerol. The first-stage larvae were investigated by examination of fecal samples from animals taking  into account the length, tail form and body size. To study the morphology of  the third-stage protostrongylid larvae  the feet of infected  mollusks  Xeropicta candaсharica were separated and placed into the artificial gastric juice where the cap was destroyed and the infected larvae were eliminated. After determination of species belonging of mature and larval nematodes the material was stored in separate test-tubes with distilled water under the low temperature (- 20 ºС) or in 70 % Ethanol for the molecular analysis. We used microscopes ML 2000 with a digital camera and Olympus CX3. DNA extraction, amplification and sequencing were performed with an automated sequencer. Phylogenetic analysis was conducted using the software Clustal X 2.0. Phylogenetic trees were created by the Neighbor–Joining method. Nucleotide sequences ITS-2 regions of species Protostrongylus rufescens  (EU018485), P. shiozawai  (AB478249),  Ortostrongylus macrotis  (EU018483),  Cystocaulus ocreatus  (EU018481) and Umingmakstrongylus pallikuukensis  (AY648409) received from the NCBI GenBank  were used in phylogenetic analysis.  Results and discussion:  Four species of adult protostrongylid nematodes: Protostrongylus rufescens, P. hobmaieri, Spiculocaulus leuckarti and Cystocaulus ocreatus were determined. DNA from four species of mature protostrongylids and larvae was amplified  by using  ITS-2 regions. Amplificate dimension of nematodes P. rufescens and P. hobmaieri was 380 base pairs (b.p.), S. leuckarti   – 388, C. ocreatus – 399 b.p. According to the  results of phylogenetic analysis and comparison of nucleotide sequences, five protostrongylid  species were found  in animals of the Caprinae subfamily:  P.  rufescens, P.  hobmaieri, Protostrongylus sp., S.  leuckarti  and  C.  ocreatus.  The morphological and molecular-genetic analysis  of detected nematodes enables the precise identification