The consistent clinical progression, shifting radiological infiltrates, and an inverted V viral-load profile suggest that worsening in week 2 is unrelated to uncontrolled viral replication but may be related to immunopathological damage.

Spontaneous pneumomediastinum (SP) unrelated to assisted ventilation is a newly recognised complication of severe acute respiratory syndrome (SARS). The objective of the present study was to examine the incidence, risk factors and the outcomes of SP in a cohort of SARS victims from a community outbreak.Data were retrieved from a prospectively collected database of virologically confirmed SARS patients. One hundred and twelve cases were analysable, with 13 patients developing SP (11.6%) at a mean ¡ SD of 19.6 ¡ 4.6 days from symptom onset.Peak lactate dehydrogenase level was associated with the development of SP. SP was associated with increased intubation and a trend towards death. Drainage was required in five cases. For patients who survived, the SP and/or the associated pneumothoraces took a median of 28 days (interquartile range: 15-45 days) to resolve completely.In conclusion, spontaneous pneumomediastinum appeared to be a frequent complication of severe acute respiratory syndrome. Further research is needed to investigate its pathogenesis. Severe acute respiratory syndrome (SARS) has been documented to be caused by a novel coronavirus (SARS-CoV) [1][2][3], which satisfied the Koch's postulations for causation [4,5]. At the time of writing, the numbers of probable SARS cases has reached 8,422 globally [6]. Two previous studies have noted the occurrence of spontaneous pneumomediastinum (SP) occasionally in patients with SARS, unrelated to assisted ventilation [7,8]. However, SP in SARS has not been systematically studied. In the present study the incidence, risk factors and the implications of the development of SP in SARS sufferers were examined. MethodsThe present study examined SP in SARS patients by retrospective analysis of a prospectively collected SARS database. Patients included in the study were consecutive SARS patients admitted to the United Christian Hospital (Hong Kong, SAR, China) during a community outbreak from March 24 to April 28, 2003. Patients met a modified WHO definition of SARS, which included fever (o38uC), cough or shortness of breath, new pulmonary infiltrates on radiological examination, in the absence of an alternative diagnosis, together with virological documentation of SARS-CoV infection (paired serology and/or positive RT-PCR for SARS-CoV from clinical specimens). All patients were treated with a standard protocol of broad spectrum antibiotics, ribavirin and a tailing regimen of corticosteroids [9]. The clinical, haematological, biochemical, radiological and virological findings were prospectively entered into a preset database, according to previous publications [1,7].Chest radiographs were taken at intervals of 1 to 3 days, depending on clinical need. SP was defined as the presence of gas in the mediastinum, occurring before assisted ventilation. For equivocal cases, high resolution computed tomography (HRCT) of the thorax would be utilised to detect this complication. All chest radiographs and HRCT were interpreted by thoracic radiologists. Results were expressed ...

The molecular epidemiological evidence suggests that most SARS-CoV from the outbreak in Hong Kong, as well as the viruses from Canada, Vietnam, and Singapore, are genetically closely linked. Three viruses found in Hong Kong in February were phylogenetically distinct from the major cluster, which suggests that several introductions of the virus had occurred, but that only one was associated with the subsequent outbreak in Hong Kong, which in turn spread globally.

The complete genomic nucleotide sequence (29.7kb) of a Hong Kong severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) strain HK-39 is determined. Phylogenetic analysis of the genomic sequence reveals it to be a distinct member of the Coronaviridae family. 5' RACE assay confirms the presence of at least six subgenomic transcripts all containing the predicted intergenic sequences. Five open reading frames (ORFs), namely ORF1a, 1b, S, M, and N, are found to be homologues to other CoV members, and three more unknown ORFs (X1, X2, and X3) are unparalleled in all other known CoV species. Optimal alignment and computer analysis of the homologous ORFs has predicted the characteristic structural and functional domains on the putative genes. The overall nucleotides conservation of the homologous ORFs is low (<5%) compared with other known CoVs, implying that HK-39 is a newly emergent SARS-CoV phylogenetically distant from other known members. SimPlot analysis supports this finding, and also suggests that this novel virus is not a product of a recent recombinant from any of the known characterized CoVs. Together, these results confirm that HK-39 is a novel and distinct member of the Coronaviridae family, with unknown origin. The completion of the genomic sequence of the virus will assist in tracing its origin.

A potent virucidal mixture containing amyl metacresol and dichlorobenzyl alcohol at low pH inactivated enveloped respiratory viruses influenza A, respiratory synctial virus (RSV) and severe acute respiratory syndrome coronavirus (SARS-CoV) but not viruses with icosahedral symmetry, such as adenoviruses or rhinoviruses. A titre of approximately 3.5 log10 TCID50 was reduced to below the level of detection within two minutes. Electron microscopy of purified influenza A virus showed extensive clumping and morphological changes in spike configuration after contact with the virucidal mixture, but no overt destruction of the viral membrane. We conclude that, formulated as a lozenge, the mixture could have significant effects in reducing the infectivity of certain infectious viruses in the throat and presumably in cough droplets, thus reducing, theoretically, opportunities for person-to-person transmission.