A prediction rule for clinical diagnosis of severe acute respiratory syndrome

Imaging of COVID-19

The novel coronavirus disease 2019 (COVID-19) emerged as the source of a global pandemic in late 2019 and early 2020 and quickly spread throughout the world becoming one of the worst pandemics in recent history. This chapter reviews the most up to date radiological literature and outlines the utility of thoracic imaging in COVID-19, defining both the common and the less typical imaging appearances during the acute and subacute phases of COVID-19. The short term complications and the long term sequela will also be discussed in the context of radiology, including pulmonary emboli, acute respiratory distress syndrome, superimposed infections, barotrauma, cardiac manifestations, pulmonary parenchymal scarring and fibrosis.

Entropy-driven amplification strategy-assisted lateral flow assay biosensor for ultrasensitive and convenient detection of nucleic acids

Accurate, sensitive and rapid nucleic acid tests are important to implement timely treatment measures and control the spread of disease. Herein, we developed a novel portable platform for highly sensitive and specific detection of nucleic acids by integrating an entropy-driven amplification strategy into lateral flow assay (LFA) biosensor. We find that introducing an entropy-driven amplification strategy yields bright intensities on the test line of LFA stirp, which results in improved sensitivity for targeted nucleic acid detection. The developed LFA biosensor showed good reproducibility, specificity and sensitivity for target DNA and H1N1-RNA detection with a low detection limit of 1.43 pM and 2.02 pM, respectively. Its practical potential was also verified by detecting the target nucleic acid in human serum. More importantly, the design of an entropy-driven amplification strategy in this portable platform retained the convenient, rapid and low-cost characterizations of LFA biosensor due to the compact amplification principle and the elimination of enzyme use. Thus, we believe that this assay biosensor will certainly report its own position in the timely detection of nucleic acid, especially when the medical environment and resources are fewer.

Comparison of confirmed COVID-19 with SARS and MERS cases - Clinical characteristics, laboratory findings, radiographic signs and outcomes: A systematic review and meta-analysis

Introduction

Within this large‐scale study, we compared clinical symptoms, laboratory findings, radiographic signs, and outcomes of COVID‐19, SARS, and MERS to find unique features.

Method

We searched all relevant literature published up to February 28, 2020. Depending on the heterogeneity test, we used either random or fixed‐effect models to analyze the appropriateness of the pooled results. Study has been registered in the PROSPERO database (ID 176106).

Result

Overall 114 articles included in this study; 52 251 COVID‐19 confirmed patients (20 studies), 10 037 SARS (51 studies), and 8139 MERS patients (43 studies) were included. The most common symptom was fever; COVID‐19 (85.6%, P < .001), SARS (96%, P < .001), and MERS (74%, P < .001), respectively. Analysis showed that 84% of Covid‐19 patients, 86% of SARS patients, and 74.7% of MERS patients had an abnormal chest X‐ray. The mortality rate in COVID‐19 (5.6%, P < .001) was lower than SARS (13%, P < .001) and MERS (35%, P < .001) between all confirmed patients.

Conclusions

At the time of submission, the mortality rate in COVID‐19 confirmed cases is lower than in SARS‐ and MERS‐infected patients. Clinical outcomes and findings would be biased by reporting only confirmed cases, and this should be considered when interpreting the data.

Severe Acute Respiratory Syndrome (SARS)

Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus (SARS-CoV), spread largely via droplets. Patients present with rapidly progressive pneumonia and respiratory failure. Diagnosis requires the demonstration of epidemiological linkage, clinical profiles, and virological evidence of SARS-CoV infection. Treatment of SARS is largely anecdotal. High-dose corticosteroid therapy might be useful for critically ill patients, but previous use of ribavirin (a broad-spectrum antiviral agent) was probably not efficacious. Some survivors of SARS suffer from avascular necrosis of hip and knee joints. Poor prognostic factors include advanced age, comorbidities, and high serum lactate dehydrogenase and neutrophil levels.

Elevated plasma surfactant protein D (SP-D) levels and a direct correlation with anti-severe acute respiratory syndrome coronavirus-specific IgG antibody in SARS patients

Pulmonary SP‐D is a defence lectin promoting clearance of viral infections. SP‐D is recognized to bind the S protein of SARS‐CoV and enhance phagocytosis. Moreover, systemic SP‐D is widely used as a biomarker of alveolar integrity. We investigated the relation between plasma SP‐D, SARS‐type pneumonia and the SARS‐specific IgG response. Sixteen patients with SARS, 19 patients with community‐acquired pneumonia (CAP) (Streptococcus pneumonia) and 16 healthy control subjects were enrolled in the study. Plasma SP‐D and anti‐SARS‐CoV N protein IgG were measured using ELISA. SP‐D was significantly elevated in SARS‐type pneumonia [median (95% CI), 453 (379–963) ng/ml versus controls 218 (160–362) ng/ml, P < 0.05] like in patients with CAP. SP‐D significantly correlated with anti‐SARS‐CoV N protein IgG (r² = 0.5995, P = 0.02). The possible re‐emergence of SARS or SARS‐like infections suggests a need for minimal traumatic techniques for following the alveolar compartment, e.g. during testing of antivirals. We suggest that monitoring systemic SP‐D may be useful in monitoring the alveolar integrity in SARS‐type pneumonia. The significant correlation between plasma SP‐D and anti‐SARS‐CoV‐specific antibodies support the role for SP‐D in interlinking innate and adaptive immune pathways.

Improvements in PM10 exposure and reduced rates of respiratory symptoms in a cohort of Swiss adults (SAPALDIA)

RATIONALE

Reductions in mortality following improvements in air quality were documented by several studies, and our group found, in an earlier analysis, that decreasing particulate levels attenuate lung function decline in adults.

OBJECTIVES

We investigated whether decreases in particulates with an aerodynamic diameter of less than 10 microm (PM10) were associated with lower rates of reporting respiratory symptoms (i.e., decreased morbidity) on follow-up.

METHODS

The present analysis includes 7,019 subjects who underwent detailed baseline examinations in 1991 and a follow-up interview in 2002. Each subject was assigned model-based estimates of average PM10 during the 12 months preceding each health assessment and the difference was used as the exposure variable of interest (DeltaPM10). Analyses were stratified by symptom status at baseline and associations between DeltaPM10 and change in symptom status during follow-up were adjusted for important baseline characteristics, smoking status at follow-up, and season. We then estimated adjusted odds ratios for symptoms at follow-up and numbers of symptomatic cases prevented due to the observed reductions in PM10.

MEASUREMENTS AND MAIN RESULTS

Residential exposure to PM10 was lower in 2002 than in 1991 (mean decline 6.2 microg/m3; SD = 3.9 microg/m3). Estimated benefits (per 10,000 persons) attributable to the observed changes in PM10-levels were: 259 (95% confidence interval [CI]: 102-416) fewer subjects with regular cough, 179 (95% CI, 30-328) fewer subjects with chronic cough or phlegm and 137 (95% CI, 9-266) fewer subjects with wheezing and breathlessness.

CONCLUSIONS

Reductions in particle levels in Switzerland over the 11-year follow-up period had a beneficial effect on respiratory symptoms among adults.

Emerging pathogens: challenges and successes of molecular diagnostics

More than 50 emerging and reemerging pathogens have been identified during the last 40 years. Until 1992 when the Institute of Medicine issued a report that defined emerging infectious diseases, medicine had been complacent about such infectious diseases despite the alarm bells of infections with human immunodeficiency virus. Molecular tools have proven useful in discovering and characterizing emerging viruses and bacteria such as Sin Nombre virus (hantaviral pulmonary syndrome), hepatitis C virus, Bartonella henselae (cat scratch disease, bacillary angiomatosis), and Anaplasma phagocytophilum (human granulocytotropic anaplasmosis). The feasibility of applying molecular diagnostics to dangerous, fastidious, and uncultivated agents for which conventional tests do not yield timely diagnoses has achieved proof of concept for many agents, but widespread use of cost-effective, validated commercial assays has yet to occur. This review presents representative emerging viral respiratory infections, hemorrhagic fevers, and hepatitides, as well as bacterial and parasitic zoonotic, gastrointestinal, and pulmonary infections. Agent characteristics, epidemiology, clinical manifestations, and diagnostic methods are tabulated for another 22 emerging viruses and five emerging bacteria. The ongoing challenge to the field of molecular diagnostics is to apply contemporary knowledge to facilitate agent diagnosis as well as to further discoveries of novel pathogens.

A mouse-adapted SARS-coronavirus causes disease and mortality in BALB/c mice

No single animal model for severe acute respiratory syndrome (SARS) reproduces all aspects of the human disease. Young inbred mice support SARS-coronavirus (SARS-CoV) replication in the respiratory tract and are available in sufficient numbers for statistical evaluation. They are relatively inexpensive and easily accessible, but their use in SARS research is limited because they do not develop illness following infection. Older (12- to 14-mo-old) BALB/c mice develop clinical illness and pneumonitis, but they can be hard to procure, and immune senescence complicates pathogenesis studies. We adapted the SARS-CoV (Urbani strain) by serial passage in the respiratory tract of young BALB/c mice. Fifteen passages resulted in a virus (MA15) that is lethal for mice following intranasal inoculation. Lethality is preceded by rapid and high titer viral replication in lungs, viremia, and dissemination of virus to extrapulmonary sites accompanied by lymphopenia, neutrophilia, and pathological changes in the lungs. Abundant viral antigen is extensively distributed in bronchial epithelial cells and alveolar pneumocytes, and necrotic cellular debris is present in airways and alveoli, with only mild and focal pneumonitis. These observations suggest that mice infected with MA15 die from an overwhelming viral infection with extensive, virally mediated destruction of pneumocytes and ciliated epithelial cells. The MA15 virus has six coding mutations associated with adaptation and increased virulence; when introduced into a recombinant SARS-CoV, these mutations result in a highly virulent and lethal virus (rMA15), duplicating the phenotype of the biologically derived MA15 virus. Intranasal inoculation with MA15 reproduces many aspects of disease seen in severe human cases of SARS. The availability of the MA15 virus will enhance the use of the mouse model for SARS because infection with MA15 causes morbidity, mortality, and pulmonary pathology. This virus will be of value as a stringent challenge in evaluation of the efficacy of vaccines and antivirals.

Assessment of intervention measures for the 2003 SARS epidemic in Taiwan by use of a back-projection method

OBJECTIVES

To reconstruct the infection curve for the 2003 severe acute respiratory syndrome (SARS) epidemic in Taiwan and to ascertain the temporal changes in the daily number of infections that occurred during the course of the outbreak.

METHOD

Back-projection method.

RESULTS

The peaks of the epidemic correspond well with the occurrence of major infection clusters in the hospitals. The overall downward trend of the infection curve after early May corresponds well to the date (May 10) when changes in the review and classification procedure were implemented by the SARS Prevention and Extrication Committee.

CONCLUSION

The major infection control measures taken by the Taiwanese government over the course of the SARS epidemic, particularly those regarding infection control in hospitals, played a crucial role in containing the outbreak.

Role of laboratory variables in differentiating SARS-coronavirus from other causes of community-acquired pneumonia within the first 72 h of hospitalization

The Centers for Disease Control and Prevention (CDC) recommend that SARS-coronavirus (SARS-CoV) testing be considered in epidemiologically high-risk patients hospitalized with community-acquired pneumonia (CAP) if no alternative diagnosis is identified after 72 h. The aim of this study was to identify routine laboratory variables that might indicate the need for SARS-CoV testing. Routine hematological/biochemical variables in patients with laboratory-confirmed SARS (2003) were compared with those in consecutive patients hospitalized June–December 2004 with radiologically confirmed CAP. Stepwise logistic regression analyses were performed to identify discriminating variables at baseline and by day 3 of hospitalization. Nasopharyngeal aspiration and antigen detection for influenza virus and respiratory syncytial virus using an immunofluorescence assay (IFA) were routinely performed in patients with CAP. Altogether, 181 patients with CAP (who remained undiagnosed by IFA) and 303 patients with SARS were studied. The mean intervals from symptom onset to admission were 3.1 and 2.8 days, respectively (p > 0.05). The etiological agent of CAP was identified retrospectively in only 39% of cases, the majority being bacterial pathogens. At baseline, age and absolute neutrophil count (ANC) were the only independent discriminating variables (p < 0.0001). Using a value of <4.4 × 10⁹/l as the cutoff for ANC, the sensitivity and specificity of ANC for discriminating SARS were 64 and 95%, respectively (AUC 0.90). By day 3 of hospitalization, age (p < 0.0001), change in ANC (p = 0.0003), and change in bilirubin (p = 0.0065) were discriminating variables. A model combining age <65 years, a change in ANC of >−3 × 10⁹/l, and a change in bilirubin of ≥0 mmol/l had a sensitivity of 43% and a specificity of 95% for SARS (AUC 0.90). There are only a few laboratory features (including lymphopenia) that clearly discriminate SARS from other causes of CAP. Nevertheless, when evaluating epidemiologically high-risk patients with CAP and no immediate alternative diagnosis, a low ANC on presentation along with poor clinical and laboratory responses after 72 h of antibiotic treatment may raise the index of suspicion for SARS and indicate a need to perform SARS-CoV testing.