How does arch form and interproximal contact size affect the 3D displacements and rotations of teeth: a finite element analysis

ABSTRACT Objective: The objective of this study was to determine how arch form and interproximal contact size displace mandibular teeth subjected to an anterior component of force (ACF). Methods: Nine finite element models (FEM) of the mandibular arch were developed using Ansys® v. 16.0 software. They were designed to evaluate the effects of three arch forms (triangular, oval, and square) and three contact sizes (point-to-point, 1 mm diameter, and 2 mm diameter). All nine models were subjected to an ACF of 53.8 N (5486 gm). Three-dimensional tooth rotations and displacements of the mandibular teeth were evaluated, from the right first molar to the left first molar. Results: Arch form had a greater effect on tooth movements than contact size. Triangular arches and point-to-point contacts produced the greatest displacements and rotations of teeth. Oval arches with 2 mm wide interproximal contact points showed the greatest stability. The right first premolar showed the greatest displacements in all of the models. Conclusions: Arch form and contact size affect interproximal tooth stability. Teeth are least stable in narrow arches with point-to-point interproximal contacts, and most stable in wider arches with larger contacts.

RESUMO Objetivo: O objetivo deste estudo foi determinar como o formato da arcada e o tamanho do contato interproximal deslocam os dentes inferiores submetidos a um componente anterior de força (CAF). Métodos: Nove modelos de elementos finitos (MEF) da arcada inferior foram desenvolvidos utilizando o software Ansys® v. 16.0. Eles foram projetados para avaliar os efeitos de três formatos de arcada (triangular, oval e quadrado) e três tamanhos de contato interproximal (ponto a ponto, 1 mm de diâmetro e 2 mm de diâmetro). Todos os nove modelos foram submetidos a um CAF de 53,8 N (5486 gm). Foram avaliados tridimensionalmente as rotações dentárias e os deslocamentos dos dentes inferiores, do primeiro molar direito ao primeiro molar esquerdo. Resultados: A forma da arcada teve um efeito maior no movimento dos dentes do que o tamanho do contato interproximal. Arcadas triangulares e contatos ponto a ponto produziram os maiores deslocamentos e rotações dos dentes. Arcadas ovais com pontos de contato interproximal de 2 mm de largura apresentaram maior estabilidade. O primeiro pré-molar direito apresentou os maiores deslocamentos em todos os modelos. Conclusões: O formato da arcada e o tamanho do contato interproximal afetam a estabilidade dos dentes. Os dentes foram menos estáveis nas arcadas estreitas com contatos interproximais ponto a ponto, e mais estáveis nas arcadas mais largas com contatos maiores.

Evaluation of screening methods for the students who had close contact with pulmonary tuberculosis patients in Shanghai / 上海预防医学

ObjectiveTo evaluate the current screening methods for the students who were in close contact with tuberculosis patients， that could accurately identify the preventive treatment subjects， and to improve the tuberculosis prevention and control in Shanghai schools. MethodsThe freshman/sophomore who were in close contact with active tuberculosis patients in the colleges in 2019 were recruited. All the subjects underwent both tuberculin skin test （TST） and QuantiFERON-TB gold in-tube （QFT） test at the enrollment. After signed the informed consent， all of the participants filled in a questionnaire and determined their baseline tuberculosis infection status. They were followed up for 2 years to monitor the conversion of infection status and the incidence of tuberculosis. ResultsFour of 9 （44.4%） positive participants had conversion to negative results， and 5 of 300 （1.7%） negative participants had conversion to positive during the 2-year follow-up， one of which was diagnosed with active tuberculosis. We assessed diagnostic agreement between QFT and TST at different cut-off values. The highest coincidence rate was 94.0% when choosing 15 mm as the cut-off value， with Kappa coefficient of 0.45 （95%CI： 0.32‒0.59）. ConclusionAlthough stricter than the national work requirements， the prevention and control of tuberculosis in Shanghai schools still need to be carried out meticulously. It's necessary to strengthen daily prevention and control measures， and improve the ability of management.

Qualitative Study on Psychological Experience of Close Contacts with COVID-19 during the Centralized Isolation Medical Observation Period / 中国医学伦理学

To analyze the psychological experience of close contacts with COVID-19 during the centralized isolation medical observation (centralized isolation for short) period, 17 close contacts of COVID-19 who received medical isolation observation at designated locations in a city of China were selected by purposive sampling using qualitative study methods, and the interviewees were interviewed by full-coverage structured telephone. By analyzing the obtained data and summarizing the themes, it was found that the psychological status of the COVID-19 close contacts during the centralized isolation period could be classified into three themes: obvious negative emotions, somatization of psychological problems, and demand for social support. During the epidemic, when close contacts were quarantined as high-risk groups, they often had complex and difficult psychological experiences. Relevant departments should actively carry out online guidance channels and offline knowledge dissemination, actively conduct psychological interventions for close contacts, assist them to develop life plans to enrich the life of the centralized isolation period. At the same time, relevant departments should do a good job in logistics and life support services, create a comfortable isolated living environment, and effectively relieve the negative emotions of close contacts of COVID-19 during centralized isolation through a variety of positive and effective measures to ensure physical and mental health.

Tuberculosis preventive treatment in children and adolescents: an observational study of secondary data

Abstract Objective To analyze the effectiveness, safety, outcomes, and associated factors of tuberculosis preventive treatment (TPT) in children and adolescents in Paraná, southern Brazil. Method This was an observational cohort study with a retrospective collection of secondary data from the TPT information systems of the state of Paraná from 2009 to 2016, and tuberculosis in Brazil from 2009 to 2018. Results In total, 1,397 people were included. In 95.4% of the individuals, the indication for TPT was a history of patient-index contact with pulmonary tuberculosis. Isoniazid was used in 99.9% of the cases with TPT, and 87.7% completed the treatment. The TPT protection was 98.7%. Among the 18 people who had TB, 14 (77.8%) became ill after the second year of treatment, and four (22.2%) in the first two years (p < 0.001). Adverse events were reported in 3.3% of cases, most of them were gastrointestinal and medication was discontinued in only 2 (0.1%) patients. No risk factors associated with the illness were observed. Conclusions The authors observed a low rate of illness in pragmatics routine conditions in TPT for children and adolescents, especially within the first two years after the end of treatment, with good tolerability and a good percentage of adherence to the treatment. TPT should be encouraged to achieve the goals of the End TB Strategy of the World Health Organization as an essential strategy to reduce the incidence rate of the disease, but studies with new schemes must continue to be carried out in real-life scenarios.

Propuesta de modalidad de catastro de infección tuberculosa en contactos escolares de colegios secundarios / Modality proposal of tuberculosis infection screening in high school contacts

Resumen El catastro sistemático de contactos con el objetivo de identificar y tratar a aquellos con infección tuberculosa es uno de los pilares establecidos por la OMS en su Estrategia de Fin a la Tuberculosis. El riesgo de infección tuberculosa en contactos escolares, aunque menor que en los domiciliarios, es significativo. Sin embargo, es bajo el cumplimiento del tratamiento preventivo y varios puntos se prestan a discusión, como ser el corte de la prueba tuberculínica a utilizar, el beneficio de iniciar un tratamiento quimioprofiláctico en ausencia de infección demostrada o de realizar estudios en contactos de casos índice no bacilíferos. Este escrito aborda dichos temas y propone, con evidencia actualizada, una modalidad de estudio para contactos en instituciones de enseñanza secundaria. Dicho catastro propone identificar a los infectados utilizando el punto de corte de 5 mm en la prueba de tuberculina, ofreciendo tratamiento preventivo y seguimiento activo solamente a aquellos con una prueba positiva.

Abstract The systematic registry of contacts with the objective of identifying and treating those with tuberculosis infection is one of the pillars established by the WHO in the end Tuberculosis Strategy. The risk of tuberculosis infection in school contacts, although lower than in households, is significant. However, compliance with preventive treatment is low and several points are open to discussion, such as the cutoff of the tuberculin test to be used, the usefulness of starting a chemoprophylactic treatment in the absence of confirmed infection or carrying out studies in contacts of non-bacilliferous index cases. This paper ad dresses these issues and proposes, with updated evidence, a screening modality for contacts in higher education institutions. This screening proposes to identify those infected using the cut-off point of 5 mm in the tuberculin test, offering preventive treatment and active follow-up only to those with a positive test.

Evaluation of sacral neuromodulation system with new six-contact points electrode for the treatment of bladder dysfunction / 中华泌尿外科杂志

Objective:To investigate the effects of sacral neuromodulation (SNM)using the new six-contact electrode vs. the four-contact electrode in patients with refractory overactive bladder.Methods:The clinical data of 29 patients underwent SNM testing therapy from January 2018 to January 2020 in China Rehabilitation Research Center were reviewed. In six-contact points electrode group 16 patients accepted SNM with new six-contact points electrode, while 13 patients in four-contact points electrode group accepted SNM with four-contact points electrode. There were no significant differences between the two group in age [(51.63±4.67) vs. (51.85±7.18) years], gender (male/female, 4/12 and 5/8), urination frequency [(22.10±9.05) vs. (21.79±8.05) times/24h], mean voided volume [(135.68±56.98) vs. (131.00±53.05) ml], and urgency score [(2.78±0.97) vs. (3.02±0.91)] (all P>0.05). The number of sensitive contact points, the ratio of reaction contact points, operation time of stage I and the success rate of two groups were calculated. Results:The mean number of sensitive points of six-contact points electrode group (3.31± 0.95) was significantly higher than that of the four-contact points electrode group (1.85± 0.38), ( P<0.05). There was no significant difference in the ratio of reaction contact points [ (96.87±6.71)% vs. (96.15± 9.39)%] and operation time of stage I [(71.25± 18.21)min vs.(68.85± 10.83)min]between six-contact points electrode group and four-contact points electrode group ( P<0.05). The contact E4 and E5 of six-contact electrodes had similar reaction voltage ( P>0.05). The implant rate of six-contact points electrode group was (14/16, 87.5%), which was higher than that of four-contact points electrode group (10/13, 76.9%), but there was no statistical difference ( P>0.05). Conclusions:This study showed that six-contact electrodes has more sensitive points compared with four-contact electrodes. Application of six contact electrodes, patients might get a higher implant rate.

Meta-analysis of infection and disease among household contacts of patients with drug-resistant tuberculosis / 中国热带医学

@#Abstract: Objective　To analyze the association between drug resistance and the risk of latent tuberculosis infection and disease among household contacts of patients with pulmonary tuberculosis, and to explore whether the compensatory mutation of drug-resistant Mycobacterium tuberculosis will enhance its pathogenicity or transmission ability. Methods　The English and Chinese databases, including PubMed, web of science, EMBASE, Cochrane library database, CNKI and Wanfang database, were searched by computer from the time of establishment of the database to January 2022. Cohort studies on the risk of infection and disease among household contacts of patients with drug-resistant and sensitive pulmonary tuberculosis were searched and screened according to the inclusion and exclusion criteria. The data were extracted and evaluated by NOS scale, using stata16.0 software meta-analysis to calculate the combined effect of tuberculosis infection and disease risk of family contacts, and carry out heterogeneity test, subgroup analysis and sensitivity analysis. Results　A total of 7 cohort studies involving 9653 TB index cases and 29, 734 house contacts were included. The results of meta-analysis showed that compared with drug-sensitive pulmonary tuberculosis patients, the risk of tuberculosis infection in house contacts of drug-resistant pulmonary tuberculosis patients was increased (OR=1.56, 95%CI=1.25-1.96, P<0.001), but there was no difference in the risk of incidence (RR=1.06, 95%CI=0.80-1.41, P=0.67>0.05). Subgroup analysis showed that the risk of latent tuberculosis infection in house contacts was affected by the study area, and the size of family contacts had an impact on the risk of TB . Sensitivity analysis showed that the results of meta-analysis were robust. Conclusion　Compared with drug sensitive TB patients, household contacts with drug-resistant TB patients had a higher risk of tuberculosis, but there was no difference in the risk of TB among the two groups.

Detección de SARS-CoV-2 en contactos estrechos asintomáticos de casos confirmados por diagnóstico molecular, provincia de Buenos Aires, Argentina / Detection of SARS-CoV-2 in asymptomatic close contacts of cases confirmed by molecular diagnosis, Buenos Aires province, Argentina

Resumen La detección de SARS-CoV-2 y su implicancia en el diagnóstico de COVID-19 han sido muy debatidas en la pandemia. El objetivo de este estudio fue evaluar el costo/beneficio de la detección de SARS-CoV-2 en contactos estrechos asintomáticos (CE) mediante el uso de distintas pruebas de diagnóstico molecular. Se estudiaron 51 CE de personas con diagnóstico de SARS-CoV-2 confirmado por RTqPCR, clasificadas por el umbral de ciclos (Ct) (<20, entre 20 y 30 y >30) en hospitales públicos de la provincia de Buenos Aires. Del total de contactos estudiados el 15,7% resultó confirmado para SARS-CoV-2; no hubo contactos positivos de casos con Ct>30. La cantidad de contactos positivos de casos con Ct<20 fue significativamente mayor que la de casos con Ct>20. Las muestras con Ct<20 se asociaron a una carga viral estimada de entre uno a cuatro órdenes de magnitud de diferencia con los rangos de Ct>20. Un 13,7% de contactos positivos fueron casos con Ct<20. De las muestras positivas confirmadas por PCR, correspondientes a la semana epidemiológica 1 de 2021 (SE1), sólo un 19,35% correspondían a muestras con Ct<20 y un 50,7% con Ct entre 20 y 30. Estos datos muestran un incremento de sólo un 3,7% de casos detectados. El esfuerzo por parte del sistema de salud pública para esta estrategia, con bajo poder predictivo, puede tener un efecto negativo para el cumplimiento del aislamiento de los contactos y podría generar una demora en los resultados de los casos sospechosos, sin aportar significativamente en el control de la pandemia.

Abstract The detection of SARS-CoV-2 and its implication in the diagnosis of COVID-19 have been highly debated in the pandemic. The objective of this study was to evaluate the cost/benefit of detecting SARS-CoV-2 in asymptomatic close contacts (CC) using different molecular diagnostic tests. A total of 51 CC of people with a diagnosis of SARS-CoV-2 confirmed by RTqPCR, classified by the cycle threshold (Ct) (<20, between 20 and 30 and >30), were studied in public hospitals in the Province of Buenos Aires. Of the total contacts studied, 15.7% were confirmed for SARS-CoV-2; there were no positive contacts of cases with Ct>30 positive. The number of positive contacts of cases with Ct<20 was significantly higher than that of cases with Ct>20. Samples with Ct<20 were associated with an estimated viral load of one to four orders of magnitude difference with Ct ranges >20. A total of 13.7% of positive close contacts were from cases with Ct<20. When studying positive samples with confirmed diagnosis by PCR, corresponding to 1 epidemiological week of 2021 (EW1), only 19.35% corresponded to samples with Ct<20 and 50.7% with Ct between 20 and 30. From these data it is shown that with the CC test only 3.7% of the cases were detected. The effort by the public health system for this strategy, with low predictive power, may have a negative effect on the fulfillment of the isolation of contacts and could generate a delay in the results of suspected cases, without contributing significantly to controlling the pandemic.

Resumo A detecção do SARS-CoV-2 e seu envolvimento no diagnóstico da COVID-19 têm sido muito discutidos durante a pandemia. O objetivo desse estudo foi avaliar a relação custo/benefício na detecção de SARSCoV- 2 em casos de contatos próximos assintomático (CP), por meio do uso de diferentes testes de diagnóstico molecular. Foram estudados 51 casos de CP de pessoas com diagnóstico de SARS-CoV-2 confirmado pelo RTqPCR, sendo classificados pelo limiar de ciclos (Ct) (<20, entre 20 e 30 e >30), em hospitais públicos da província de Buenos Aires. Do total de contatos estudados, 15,7% foram confirmados para SARS-CoV-2, não houve contatos positivos de casos com Ct>30. O número de contatos positivos de casos com Ct<20, foi significativamente maior que os casos com Ct>20. As amostras com Ct<20 foram associadas a uma carga viral estimada de uma a quatro ordens de magnitude de diferença com os intervalos de Ct>20. Dos casos positivos, 13,7% foram com Ct<20. Das amostras positivas confirmadas por PCR, correspondentes à semana epidemiológica 1 de 2021 (SE1), apenas 19,35% correspondiam a amostras com Ct>20 e 50,7% com Ct entre 20 e 30. Esses dados mostram incremento de apenas 3,7% de casos detectados. O esforço por parte do sistema de saúde pública para essa estratégia, com baixo poder preditivo, pode ter um efeito negativo no cumprimento do isolamento dos contatos e poderia gerar uma demora nos resultados dos casos suspeitos, sem contribuir significativamente para o controle da pandemia.

Relationship between presence of abfractions and premature contacts

ABSTRACT: Abfractions (AFs) are non-carious cervical lesions considered of multifactorial etiology by several authors. Objective: Relate the presence of premature contacts and AFs. Materials & Methods: The original number of students to be analyzed were 117, 36 of whom (equal amount of women and men) were finally chosen for presenting premature contacts. 19 of them presented abfractions. A survey was conducted with questions on issues like toothbrushing habits, diet and some gastric disorders; besides the participants had to take the Hamilton Anxiety Rating Scale. Then, stone models were obtained and mounted for further occlusal analysis with WCM ® semi-adjustable articulator searching the abfractions and their coincidence with premature contacts. Fisher's exact test (p<0,05) was used to associate AF with toothbrushing habits, diet, burning symptoms and gastroesophageal reflux. Chi-square test (p<0,05) was used to associate AFs and premature contacts. Student's t-distribution was used to associate AFs with anxiety. Results: There was a significant relationship between AFs presence and premature contacts (p=0,00). There was not a significant relationship between presence of AFs and toothbrushing habits and diet. There was not a significant relationship between presence of AFs and anxiety. Conclusions: AF presence do associate with premature contacts in the same affected tooth.

Seguimiento de los contactos de casos de tuberculosis / Follow-up of Contacts of Tuberculosis Cases

Introducción: La tuberculosis constituye la principal causa de muerte en el mundo por enfermedad infecciosa. Objetivo: Verificar el cumplimiento de las acciones de control de foco de los contactos de casos de tuberculosis. Métodos: Estudio descriptivo, transversal. Universo constituido por los 338 contactos identificados de 10 casos de tuberculosis. Los datos procedieron de encuestas epidemiológicas, base de datos de morbilidad y tarjetas de notificación de la unidad municipal de higiene y epidemiologia del municipio Boyeros. Se utilizaron las variables: edad, sexo, nivel educacional y ocupación. Se identificaron los factores de vulnerabilidad en los contactos y se verificó cumplimiento del examen médico, los complementarios, realización y resultado de prueba de tuberculina, quimioprofilaxis y seguimiento. Resultados: Prevaleció el sexo masculino (64,2 por ciento) y los mayores de 65 años (46,7 por ciento). Los grupos vulnerables más frecuentes fueron los contactos en unidades de salud con internamiento prolongado y más de 60 años (87,2 por ciento y 62,1 por ciento, respectivamente). No se detectó el número real de contactos y convivientes ni fue investigado el 100 por ciento. Las pruebas de tuberculina realizadas arrojaron el mayor porciento de no reactores, el 90 por ciento de los contactos recibieron quimiprofilaxis y su seguimiento fue deficiente. Conclusiones: La no detección oportuna de los contactos y convivientes de casos de tuberculosis y los incumplimientos de su estudio constituyeron las principales deficiencias de los controles de foco realizados. El seguimiento de los contactos fue inadecuado, lo que pudiera propiciar la aparición de nuevos casos de tuberculosis en el municipio(AU)

Introduction: Tuberculosis is worldwide the main cause of death due to infectious disease. Objective: To verify compliance with outbreak control actions associated with contacts of tuberculosis cases. Methods: Descriptive and cross-sectional study. The universe was made up of the 338 contacts identified from ten cases of tuberculosis. The data came from epidemiological surveys, morbidity database and notification cards of the municipal hygiene and epidemiology unit of Boyeros Municipality. The following variables were used: age, sex, educational level and occupation. The vulnerability factors in the contacts were identified, as well as compliance with medical examination, complementary tests, performance and result of tuberculin test, chemoprophylaxis and follow-up. Results: The male sex (64.2 percent) and people over 65 years of age (46.7 percent) prevailed. The most frequent vulnerable groups were contacts in health units with prolonged hospitalization and aged over 60 years (87.2 percent and 62.1 percent, respectively). The actual number of contacts and partners was not detected, nor 100 percent of them were investigated. The tuberculin tests carried out showed the highest percentage of non-reactors. 90 percent of the contacts received chemoprophylaxis and their follow-up was poor. Conclusions: There was no timely detection of the contacts and cohabitants of tuberculosis cases and no compliance with their study, which constituted the main deficiencies of the outbreak controls carried out. The follow-up of the contacts was inadequate, which could lead to the appearance of new cases of tuberculosis in the municipality(AU)

Hanseniasis in the municipality of Western Amazon (Acre, Brazil): are we far from the goal of the World Health Organization?

ABSTRACT Background: Hanseniasis is a public health concern in developing countries. Although a decrease in the number of new cases in Brazil has been reported, there is a prevalence above that recommended in some regions. Aims: Considering the goal of the World Health Organization (WHO) to accelerate towards a leprosy-free world from 2020, the aim of this study was to analyze the epidemiological profile and leprosy trends in the city of Cruzeiro do Sul, Acre, Brazil. Methods: This retrospective cohort study analyzed the epidemiology and trends of hanseniasis between 2005 and 2018, monitoring socioeconomic and clinical epidemiological variables obtained from the Information System of Notifiable Diseases of Hanseniasis (SINAN) database. Results: A total of 422 cases of hanseniasis (284 male, 138 female) were included. The questionnaire of six patients was incomplete. The highest number of cases (89) was recorded in 2006 (11.7/10,000 inhabitants). The borderline clinical form was most common, with 45.4% of cases. Throughout the historical series, the rate of annual percentage change in the detection of new cases and cases with grade 2 disability showed a decreasing profile, at −13.9 [95% CI: −19.1, −8.2] and −13.1 [95% CI: −21.8, −5.5], respectively. The same rates were observed in patients below 15 years of age. Limitations: This study reflects the scenario in one reference center and data were obtained retrospectively. Conclusions: The incidence of hanseniasis in this reference center is declining gradually; however, the indicators show active disease transmission and late diagnosis.

Epidemic Characteristics of the Novel Coronavirus Delta Variant in Guangzhou and Grid Crowd Management Based on Public Security Forensic Perspective / 法医学杂志

Abstract： Objective To analyze the first epidemic spread of the novel coronavirus Delta variant in China based on public security forensic perspective, investigate its transmission characteristics, contributing factors, and epidemiologic research experience, and provide a reference for the prevention and control of the epidemic caused by the novel coronavirus variant. Methods Based on the information that public security forensic experts obtained from front-line epidemiologic research, the gender, age, place of residence, transmission route and infectivity of the coronavirus disease 2019 （COVID-19） confirmed cases, asymptomatic infected persons and their close contacts in Guangzhou caused by the novel coronavirus Delta variant were analyzed. The basic reproduction number （R0） during this epidemic in Guangzhou was calculated. Results Among the 153 cases infected with novel coronavirus Delta variant in the epidemic, 63 cases were male and 90 cases were female, their age ranging from 1 to 92 years, with a median age of 49 years. The main route of transmission was close contact, including dining together, co-living, and close contact in the same residential building. There were 31 cases of family clusters, 25 of which were in Liwan District. The epidemic lasted from May 26 to May 29, and the R0 remained above 4.0. After May 30, R0 began to decline and remained below 1.0 from June 7. Conclusion The novel coronavirus Delta variant is highly infectious, the crowd is generally susceptible to infection and family cluster cases are easy to occur. So, it is necessary to precisely prevent and control this strain. Public security forensic experts have both medical literacy and criminal investigation capabilities, they can play a more professional role in epidemic prevention and control.

Moxibustion on mental disorder in close contacts of coronavirus disease 2019: a randomized controlled trial / 中国针灸

OBJECTIVE@#To observe the effect of moxibustion combined with @*METHODS@#A total of 240 close contacts of COVID-19 were randomized into an observation group (120 cases, 18 cases dropped off) and a control group (120 cases, 58 cases dropped off). Conventional observation was adopted in the control group. Moxibustion combined with Daiwenjiu plaster was given in the observation group, moxibustion was applied at Zusanli (ST 36), Hegu (LI 4) and Shenque (CV 8), 10 min each acupoint, once a day; @*RESULTS@#In the follow-up, SRQ-20 score was decreased compared before treatment (@*CONCLUSION@#Moxibustion combined with

Incidence of Latent Tuberculosis Infection in a Study of School Contacts Comparing Two Cut-off Points of the Tuberculin Test / Incidencia de infección tuberculosa latente en un estudio de contactos escolares comparando dos puntos de corte de la prueba de tuberculina

Introduction: The risk of tuberculosis infection is associated with close and prolonged contact. Daily contact, poorly ventilated classrooms or delay in diagnosing the index case in a school setting could contribute to contagion. Objective: To know the incidence of latent tuberculosis infection (LTBI) in school contacts comparing two cut-off points of the tuberculin test (PPD, Purified Protein Derivative): ≥ 10mm and ≥ 5mm. To determine the degree of compliance with the performance of control and chemoprophylaxis (ChP) studies. Materials and Methods: We carried out a retrospective analysis of bacillary TB school contacts in teenagers between 12 and 19 years old of the Programmatic Area of the Hospital Parmenio Piñero between February 2016 and December 2017. The evaluation included chest x-ray, lab tests and PPD. We analyzed 2 cut-off points of the PPD: ≥ 10mm and ≥ 5mm, and repeated the test after 3 months in cases with negative results. Primary ChP with isoniazid was indicated for all the contacts, and secondary ChP for those with basal PPD+ or conversion at the third month. We considered ChP compliance in cases where patients followed > 80% of the indicated regime. Results: 331 (89%) of 373 students to be evaluated participated in the study. TB was diagnosed in 4 students (1.2%) through chest x-ray, and they were excluded. Within the remaining 327, the mean age was 15 ± 1.6 years, and 132 (40%) were male. The basal PPD was ≥ 10mm in 20 cases (6.1%), being more frequent in the group of 16-19 years versus the 12-15 years: 10.7% vs. 3.1%; p = 0.004. There wasn't any significant difference regarding sex. 135 contacts (45%) did the second PPD, and 3 conversions were found (2.2%). Primary ChP was indicated for everyone, and secondary ChP for 23 contacts, with 75% and 26% compliance respectively, and without any significant association with age or sex. 4 adverse events were reported (1.2%): polineuritis (n=2), skin allergy and food intolerance. 63 contacts (19.3%) were positive PPD, with PPD ≥ 5mm, being more frequent in males: 26.5% vs. 14.4%, p = 0.006; and in 16-19 vs. 12-15 years: 28.2% vs. 13.2%; p < 0.001. With the second PPD we observed 3 conversions (2.2%). Conclusion: We found 6.1% of LTBI considering a PPD+ ≥ 10mm and 19.3% with PPD ≥ 5mm. Compliance with the second PPD and the secondary ChP scheme was low.

An investigation of a family COVID-19 cluster / 上海预防医学

Objective To investigate epidemic characteristics of a family cluster of COVID-19, and to provide reference in improving the criteria for exclusion diagnosis and medical observation of close contacts. Methods Field epidemiological method was used to investigate the cases and close contacts of a family cluster of COVID-19 in Pudong New Area.Descriptive analysis was conducted on epidemiological data.Real-time fluorescence quantitative RT-PCR was used to detect 2019-nCoV nucleic acid in the respiratory tract specimens. Results There were two confirmed cases and one suspected case in the family cluster.The source of infection was Case 1 with a living history in Wuhan, Hubei Province.Case 2 and Case 3, as close contacts, received 14-day medical observation in a centralized isolation site.Case 2 showed symptoms 4 days after the onset of Case 1, and the diagnosis of COVID-19 was excluded after two negative nucleic acid tests during the isolation period.However, after the expiration of isolation, Case 2 was diagnosed positively for COVID-19 and Case 3 was suspected first and then excluded. Conclusion Daily close contact is critical for COVID-19 transmission and is the major cause of family clustering.Once the close contacts show symptoms, diagnosis should be made by combining the results of nucleic acid test, chest CT test, serological test, etc.We suggest to grade the risk of infection for close contacts, and to strengthen the standard of medical observation for close contacts with high risk of infection.

Characteristics of COVID-19 clusters in Lishui / 预防医学

Objective@#To analyze the epidemiological characteristics of coronavirus disease 2019 ( COVID-19 ) clusters in Lishui, so as to provide basis for the prevention and control of COVID-19 clusters.@*Methods@#The data of COVID-19 clusters in Lishui from January 23 to March 29, 2020 were collected through China Disease Control and Prevention Information System-Public Health Emergency Information System, and analyzed time, space, scale, source of infection, exposure and transmission route by descriptive epidemiological method. @*Results@#There were 31 cases in 8 clusters ( about 4 cases per cluster ), with no death. The report time was bimodal, peaked first from January 20 to February 10 with 4 clusters imported from domestic and peaked second from March 1 to 29 with 4 clusters imported from overseas. Qingtian County reported 4 clusters, Liandu District, Yunhe County, Qingyuan County and Jingning County each reported 1 cluster. Thirteen cases were restaurant employees, accounting for 41.94%. The cases were mainly occurred in the condition that exposed in the same family ( 6 clusters ), in the same dinner and car ( 1 clusters ), and in the same party ( 1 clusters ). The exposure modes that caused more cases infected were through the same family (9 cases) and through the same dinner and car ( 6 cases ). There were 3 clusters with first-generation cases, 3 clusters with second-generation cases and 2 clusters with third-generation cases. The recurrence rate of the 8 clusters ranged from 1.49% to 7.69%, with a median of 3.47%. @*Conclusions@#The COVID-19 clusters in Lishui imported from domestic in the early stage and later from overseas. Most cases were reported from Qingtian County, were engaged in catering business, and exposed by living with families.

Features of close contacts of COVID-19 cases in Jiulongpo District / 预防医学

Objective@#To explore the features of close contacts of coronavirus disease 2019 ( COVID-19 ) cases in Jiulongpo District, Chongqing, so as to provide evidence for the management of close contacts and the control of the epidemic.@*Methods@#Demographic characteristics, contact history and medical records of close contacts of COVID-19 cases in Jiulongpo District from January 22 to April 10, 2020 was collected according to the COVID-19 Prevention and Control Program ( sixth version ) . Descriptive statistical analysis was performed.@*Results@#Totally 602 close contacts were found, and 30 of them were infected, with an attack rate of 4.98%. Twenty-seven cases were diagnosed before February 10. The close contacts mainly aged from 20 to 59 years ( 457, 75.91% ) ; most were relatives of COVID-19 cases ( 219, 36.38% ) , and 64 (10.63%) were medical staff. Most contacted occasionally ( 338, 56.15% ), at home ( 190, 31.56% ) , and through the same meal ( 181, 30.07% ) . The attack rate of close contacts aged 40 years and over was 7.49%, which was higher than 2.37% of those aged under 40 years ( P<0.05 ). The attack rate of close contacts increased with contact frequency ( P<0.05 ) . The attack rates of close contacts were significantly different in different relations with cases, contact places and contact modes ( P<0.05 ); the attack rates of colleagues and relatives were 20.41% and 8.68%; the attack rates of close contacts in the workplace settings and family were 17.54% and 10.00%; the attack rates of sharing the same bed, living in the same room and working in the same room were 44.44%, 18.60% and 17.24%.@*Conclusions @#The close contacts of COVID-19 cases in Jiulongpo District, Chongqing who aged 40 years or above, exposed in family settings and in the workplace were associated with higher risk of infection.

Implementation of centralized quarantine for close contacts in a community of Shanghai during COVID-19 epidemic / 中华全科医师杂志

Since the key point of prevention and control of new coronavirus infection (COVID-19) in the community is to block the spread, the centralized quarantine for close contacts with confirmed or suspected cases is the most effective way in breaking the chain of transmission. A community centralized quarantine site was set up by Fenglin Community Health Service Center for medical observation of close contacts. The detailed plan and management of the centralized quarantine site, and the implementation experiences are introduced in this article to provide reference for medical institutions involved in the prevention and control of COVID-19 epidemic.

Potential false-positive rate among the 'asymptomatic infected individuals’ in close contacts of COVID-19 patients / 中华流行病学杂志

Objective@#As the prevention and control of COVID-19continues to advance, the active nucleic acid test screening in the close contacts of the patients has been carrying out in many parts of China. However, the false-positive rate of positive results in the screening has not been reported up to now. But to clearify the false-positive rate during screening is important in COVID-19 control and prevention.@*Methods@#Point values and reasonable ranges of the indicators which impact the false-positive rate of positive results were estimated based on the information available to us at present. The false-positive rate of positive results in the active screening was deduced, and univariate and multivariate-probabilistic sensitivity analyses were performed to understand the robustness of the findings.@*Results@#When the infection rate of the close contacts and the sensitivity and specificity of reported results were taken as the point estimates, the positive predictive value of the active screening was only 19.67%, in contrast, the false-positive rate of positive results was 80.33%. The multivariate-probabilistic sensitivity analysis results supported the base-case findings, with a 75% probability for the false-positive rate of positive results over 47%.@*Conclusions@#In the close contacts of COVID-19 patients, nearly half or even more of the 'asymptomatic infected individuals’ reported in the active nucleic acid test screening might be false positives.

Analysis of family cluster infection with Novel Coronavirus Pneumonia / 中华急诊医学杂志

Objective@#To explore the regularity and characteristics of the transmission of Novel Coronavirus Pneumonia(NCP) in crowd, for provide a reference for pre-hospital first aid to identify and screen NCP and close contact, at the same time to improve protection awareness and reduce infection rates.@*Method@#Retrospective analysis about the cases of familial aggregation transferred by Beijing Emergency Medical Center between January 20 and February 10, 2020,collect relevant information,including basic information,contact history,symptoms and signs, clinical outcome, etc.@*Results@#The mean incubation period of familial cluster cases was 5.6d,mean time from onset of symptoms to first visit was 1.8d;Among the 5 family cluster cases, 4 had fever,mean body temperature 38ºC, the Sp02 averaged 96%; Among the 5 family cluster cases, 4 had cough, 2 had fatigue, and 1 had dyspnea.@*Conclusion@#People are susceptible to infection to NCP,it spreads easily between close contacts, effective isolation is the focus of prevention and control among family members, it is also one of the difficulties of prevention and control.