1. The sensitivity of the Guaiac test for occult blood in stool is lower than its specificity.2. Broad dispersion of the validity characteristics of the fecal occult blood tests was observed.3. The validity of tests for occult blood was higher when they were used for detection of colorectal cancer than of colon polyposis.4. The highest validity rate has been demonstrated for the immunochemical test when it was used for colon cancer screening.
Relevance. It is relevant to study the features of the formation and duration of the humoral immune response to a new coronavirus infection in a high-risk group of infection - among medical workers. Aims. To study the dynamics of the levels of specific antibodies (IgM and IgG) to SARS-CoV2 in unvaccinated MRs of the temporary infectious diseases hospital to assess the trends of the individual humoral immune response to a new coronavirus infection. Materials and methods. We monitored IgM and IgG to SARS-CoV-2 in 68 unvaccinated healthcare workers monthly from July 2020 to July 2021 by two-stage direct solid-phase ELISA using the test systems «SARS-CoV-2-IgG-ELISA-BEST» and «SARS-CoV-2-IgM-ELISA-BEST», Russia. Among them, there were 26.5% men and 73.5% women, the average age was 43.5 ± 1.51 years, doctors 52.9%, paramedical personnel 36.8% and junior staff 10.3%. 69.1% had a history of clinical manifestations of COVID19, among them 42.7% had a mild infection, 20.6% had a moderate infection, and 5.9% had a severe infection, 30.9% were asymptomatic. Statistical processing were carried out using the methods of variation statistics using the Excel statistical package and the WinPepi software product (version 11.65). Results. A decrease in the geometric mean value of IgM titers to SARS-CoV-2 (average monthly decrease of 6.40%) and an increase in the geometric mean value of IgG titers (average monthly increase of 4.26%). An individual assessment of the dynamics of antibodies from the day with the first positive result showed a decrease in the geometric mean values of antibody titers and IgM and IgG to SARS-CoV-2 (monthly average decrease of -23.56% and -1.18%, respectively). An individual assessment of the immune response made it possible to distinguish three groups according to the dynamics of IgM: M0 -IgM in the blood were absent (50 ± 5.7446%); M1 -IgM persisted for 1–2 months, followed by a rapid decrease in titer (16.176 ± 3.7943%); M2 – IgM remained in the blood for three or more months (33.824 ± 5.1033%). By the nature of the dynamics of IgG MR were divided into four troupes. With a downward trend in IgG titer: G0 – IgG does not exceed 95% of the upper confidence limit of the individual trend in any of the samples taken (19.118 ± 4.7686%), G1 – does not exceed 95% of the upper confidence limit of the individual trend starting from 3 months after the start observations (4.412 ± 2.4903%), G2 – there is an excess of 95% of the upper confidence limit of the individual trend starting from 3 months after the start of observation (69.118 ± 5.6027%); G3 – with a trend of increasing IgG titer (7.353 ± 3.1651%). Сonclusions. The results of serological monitoring as a whole indicate the formation of herd immunity in this cohort. Monitoring the intensity of the individual immune response to SARS-CoV-2 throughout the year reflects the natural course of the infectious process and is the basis for vaccination against COVID-19. The results of serological monitoring can be used to predict the epidemiological situation, plan specific and non-specific COVID-19, personalization of vaccination.
Background. The ongoing COVID-19 pandemic generates the urgent need of monitoring the herd immunity among healthcare workers as a high-risk group for infection. Aim. Determining the level and structure of population immunity to SARS-CoV-2 in the medical workers during the second peak of COVID-19 from August to November 2020. Material and methods. The study involved 15,158 medical workers from 91 medical organizations of the Republic of Tatarstan. The age of the examined stuff members varied from 18 to 74 years, the average age was 45.480.1016 years, most of them were women (13 627, 89.870.258%). Testing for the presence of total antibodies (immunoglobulin classes G, A and M) to SARS- CoV-2 was performed once by the enhanced chemiluminescence method. Statistical processing was carried out by methods of variation statistics and correlation analysis according to the Pearson method using MS Excel and WinPepi. Results. Seroprevalence to SARS-CoV-2 in medical workers was 35.230.388%. An increase in seropositive individuals level from 27.440.265% in August to 57.910.499% in November and an increase in the average geometric mean titer of total antibodies (immunoglobulin classes A, M, G) from 84.43 in August to 101.09 in November 2020 were detected. The level of individuals with antibodies increased with age from 18 to 59 years and decreased in group of 6070 years. The largest proportion of seropositive to SARS-CoV-2 individuals was found among junior (42.011.384%) and middle grade (37.50.527%) medical staff of hospitals for patients with COVID-19, ambulance and emergency stations. Among the seropositive to the SARS-CoV-2 workers the proportion of asymptomatic forms of infection was 84.970.498%. According to the level of seroprevalence, municipal districts of the Republic of Tatarstan were divided into three groups: moderate 8.939.0; average 42.949.6, high level 53.164.4. Сonclusion. An increase in seroprevalence to SARS-CoV-2 was revealed among medical workers of the Republic of Tatarstan from August to November 2020 during the second peak of COVID-19.
Prevention of diseases caused by Yersinia pseudotuberculosis and Yersinia enterocolitica is currently one of the urgent health problems in many countries of the world. Despite the efforts made to prevent the occurrence of these diseases, since the 60s of our century, the incidence of pseudotuberculosis and yersiniosis has been steadily increasing and ranges from 6 to 200 cases per 100 thousand population in different territories [2, 5, 7, 8].
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