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ObjectiveTo characterize a cluster epidemic of coronavirus disease 2019 （COVID-19）on campus in Baotou city and provide evidence for the prevention and control of COVID-19 in universities. MethodsField epidemiological investigation was conducted to determine the confirmed cases and close contacts in the cluster epidemic of COVID-19 in a university of western China in 2022. Descriptive analysis was utilized to illustrate the epidemic timeline and schematic diagram. Real-time quantitative fluorescent PCR（RT-PCR） was used to detect the nucleic acid of SARS-CoV-2 in the collected samples. ResultsA total of eight students were infected in the cluster epidemic on campus， including 2 confirmed cases and 6 asymptomatic cases. Case A1 infected other 7 students in the same dormitory or on the same floor by close contact. After a 10-day quarantine and medical observation， no further case was reported. The overall incidence rate was 1.22% and the incidence rate among close contacts was 2.24%. ConclusionThis cluster epidemic of COVID-19 is characterized by strong and fast transmission. Repeated contact with no personal protection in confined space is highly vulnerable to cluster epidemic. Prevention of cluster epidemics on campus remains crucial to contain the epidemic. Therefore， it is necessary to strengthen the management of campus containment， interrupt the transmission route， identify close contacts and implement quarantine management as early as possible to avoid the cluster epidemics on campus.
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Objective:To investigate the in vitro viability of rabies virus in tissues and body fluid samples. Methods:The viability of rabies virus in tissues and suspensions was analyzed by virus titer determination method, direct immunofluorescence, RT-PCR and laboratory techniques for virus isolation.Results:With the increase of temperature, the viability of rabies virus in brain tissues and suspensions decreased gradually. Rabies virus lost infectivity after 30 min at 56℃, but remained viable in tissues for 7 d at 37℃. The virus showed no viability after 1 h at pH9.6. The rabies virus in suspensions could be completely inactivated after the stimulation with ethanol at a final concentration above 30%, sodium hypochlorite above 500 mg/L or benzalkonium bromide above 100 mg/L for 3 min. It was found that 80% acetone had the strongest inactivation effect on rabies virus in tissues, and no virus could be isolated after soaking for 4 h.Conclusions:Rabies virus was not tolerant to high temperature and relatively stable in the environment with pH6.8-7.4. Common disinfectants could kill the virus. This study provided detailed data about the viability of rabies virus in vitro, which would be conducive to the prevention and control of rabies.
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<p><b>OBJECTIVE</b>To observe the effect of Congrong powder preparation on erythrocyte parameter and the index of blood rheology in healthy rats.</p><p><b>METHOD</b>The 50 rats were randomly divided into 5 groups ( physiological saline group, testosterone propionate group, large-dose administered group, moderate-dose administered group, small-dose administered group). Blood were taken to determine erythrocyte parameter and the index of blood rheology.</p><p><b>RESULT</b>Congrong powder preparation had no effect on erythrocyte parameter. There was an increase in whole blood viscosity, whole blood reduction viscosity, and in the erythrocyte rigidity index in the large-dose administered group.</p><p><b>CONCLUSION</b>Congrong powder can influence deformability and some related characters of erythrocytes.</p>