ABSTRACT
The coronavirus disease 2019 (COVID-19) pandemic has become a public-health crisis worldwide. Accurate identification of the virus that causes COVID-19, SARS-CoV-2, carriers of SARS-CoV-2, and infected people is crucial for the prevention and control of this pandemic. Detection of the nucleic acids (NAs) of SARS-CoV-2 is one of the main criteria for COVID-19 diagnosis. Pharyngeal swabs (PSs) and fecal specimens (FSs) tend to be positive for SARS-CoV-2. However, there have been no reports of differences in the detection results of SARS-CoV-2 NAs in PSs and FSs of COVID-19 patients and asymptomatic SARS-CoV-2 infected persons at different exposure times. Forty-six patients diagnosed with COVID 19 in Nanyang City, China, from 2 February to 17 February 2020 and 27 asymptomatic SARS-CoV-2 infected persons screened through epidemiologic history and PSs and FSs at different exposure times were evaluated through detection of SARS-CoV-2 NAs. COVID-19 patients and asymptomatic SARS-CoV-2 infected persons had the highest positive rate of NAs in PSs at week 2 and the highest positive rate for NAs in FSs at week 3. The positive rate of NAs in PSs was significantly higher than that of FSs (P < 0.05). The difference in the positive rate of NAs in PSs between the two groups at 1, 3, and 4 weeks was significant (P < 0.05). The difference in the positive rate of NM in FSs between the two groups at 1-4 weeks was not significant (P > 0.05). The time for SARS-CoV-2 NAs to test positive in FSs lagged behind that for SARS-CoV-2 NAs to test positive in PSs (P > 0.05). The time for SARS-CoV-2 NAs to test positive in the PSs and FSs of asymptomatic SARS-CoV-2 infected persons lagged behind that for COVID-19 patients (P > 0.05). There was no significant difference in the average cycle threshold (Ct) value of the ORFlab gene and N gene of PSs and FSs between COVID-19 patients and asymptomatic SARS-Cov-2 infected persons at each exposure time tested (P > 0.05). The more severe the COVID-19, the higher was the positive rate of SARS-CoV-2 NAs in PSs and FSs, and the shorter was the time taken for SARS-CoV-2 NAs to test positive (P < 0.05). The re-positive rate of asymptomatic SARS-CoV-2 infected persons was 14.81% (4/27), higher than that of COVID-19 patients (6.52%;3/46), and the difference was significant (X2=8.193, P=0.016). Our study suggests that SARS-CoV-2 has a fecal mouth transmission route. The time taken for SARS-CoV-2 NM from FSs to turn positive lags behind that for SARS-CoV-2 NAs in PSs to turn positive, and the positive rate is lower. Test specimens should be selected according to different exposure times. Attention should he paid to younger asymptomatic SARS-CoV-2 infected persons.
ABSTRACT
Pulmonary embolism (PE) is a potentially life-threatening condition that requires immediate medical intervention. Although PE was previously thought to occur infrequently in the pediatric population, recent studies have found a higher-than-expected prevalence of PE in the pediatric population of up to 15.5%. The imaging modality of choice for detecting PE in the pediatric population is multi-detector CT angiography, although MRI is assuming a growing and more important role as a potential alternative modality. Given the recent advances in both computed tomography pulmonary angiography (CTPA) and MRI techniques, a growing population of pediatric patients with complex comorbidities (such as children with a history of surgeries for congenital heart disease repair), and the recent waves of coronavirus disease 2019 (COVID-19) and multisystem inflammatory syndrome in children (MIS-C), which are associated with increased risk of PE, there is new and increased need for an up-to-date review of practical CT and MRI protocols for PE evaluation in children. This article provides guidance for up-to-date CT and MR imaging techniques, reviews key recent studies on the imaging of pediatric PE, and discusses relevant pediatric PE imaging pearls and pitfalls, in hopes of providing readers with up-to-date and accurate practice for imaging evaluation of PE in children.
ABSTRACT
The presence of SARS-CoV-2 mutants, including the emerging variant B.1.1.7, has raised great concerns in terms of pathogenesis, transmission, and immune escape. Characterizing SARS-CoV-2 mutations, evolution, and effects on infectivity and pathogenicity is crucial to the design of antibody therapies and surveillance strategies. Here, we analyzed 454,443 SARS-CoV-2 spike genes/proteins and 14,427 whole-genome sequences. We demonstrated that the early variant B.1.1.7 may not have evolved spontaneously in the United Kingdom or within human populations. Our extensive analyses suggested that Canidae, Mustelidae or Felidae, especially the Canidae family (for example, dog) could be a possible host of the direct progenitor of variant B.1.1.7. An alternative hypothesis is that the variant was simply yet to be sampled. Notably, the SARS-CoV-2 whole-genome represents a large number of potential co-mutations. In addition, we used an experimental SARS-CoV-2 reporter replicon system to introduce the dominant co-mutations NSP12_c14408t, 5'UTR_c241t, and NSP3_c3037t into the viral genome, and to monitor the effect of the mutations on viral replication. Our experimental results demonstrated that the co-mutations significantly attenuated the viral replication. The study provides valuable clues for discovering the transmission chains of variant B.1.1.7 and understanding the evolutionary process of SARS-CoV-2.