Use of simple laboratory features to distinguish the early stage of severe acute respiratory syndrome from dengue fever

BACKGROUND

The diagnosis of severe acute respiratory syndrome (SARS) is difficult early in the illness, because its presentation resembles that of other nonspecific viral fevers, such as dengue. Dengue fever is endemic in many of the countries in which the large SARS outbreaks occurred in early 2003. Misdiagnosis may have serious public health consequences. We aimed to determine simple laboratory features to differentiate SARS from dengue.

METHODS

We compared the laboratory features of 55 adult patients with SARS at presentation (who were all admitted before radiological changes had occurred) and 147 patients with dengue. Features independently predictive of dengue were modeled by multivariate logistic regression to create a diagnostic tool with 100% specificity for dengue.

RESULTS

Multivariate analysis identified 3 laboratory features that together are highly predictive of a diagnosis of dengue and able to rule out the possibility of SARS: platelet count of <140 x 10(9) platelets/L, white blood cell count of <5x10(9) cells/L, and aspartate aminotransferase level of >34 IU/L. A combination of these parameters has a sensitivity of 75% and a specificity of 100%.

CONCLUSIONS

Simple laboratory data may be helpful for the diagnosis of disease in adults admitted because of fever in areas in which dengue is endemic when the diagnosis of SARS needs to be excluded. Application of this information may help to optimize the use of isolation rooms for patients presenting with nonspecific fever.

[Preparation of monoclonal antibodies against SARS coronavirus and staining usage in lung autopsy specimens]

OBJECTIVE

To prepare monoclonal antibodies against SARS coronavirus (SARS-CoV) on the purpose to explore the diagnosis methods of SARS.

METHODS

Female BALB/C mice were immunized with disinfected SARS-CoV (PUMC01) and the spleen cells were fused with myeloma NS-1 cells. The hybridoma cell strains were screened by enzyme-linked immunosorbent assay (ELISA), indirect fluorescent-antibody assay (IFA) and Western blotting. Autopsy lung tissue sections from SARS patients were stained with ascites of monoclonal antibody (M2 strain) by immunohistochemical technique.

RESULTS

Six strains of hybridomas that produced the monoclonal antibodies against SARS-CoV were obtained. The hybridomas were tested to have specific reactions with SARS-CoV and no cross-reactivates with other common respiratory disease causing pathogens. Of the 6 strains, 1 was identified as the immunoglobulin G3 (IgG3) isotype, 5 were IgG1. Western blotting showed that one strain (M2) reacted with 68000- Dalton (68KD) protein and four strains with 27000-dalton (27KD) protein. Band of M4 stain was not got by western blotting. Brown particles were seen in macrophages and pneumocytes in autopsy lung tissues from SARS patients.

CONCLUSION

Monoclonal antibodies we made were specific to the SARS-CoV, and they had been used to detect SARS-CoV in autopsy lung tissues specimens with positive results.

Macaque model for severe acute respiratory syndrome

Rhesus and cynomolgus macaques were challenged with 10(7) PFU of a clinical isolate of the severe acute respiratory syndrome (SARS) coronavirus. Some of the animals developed a mild self-limited respiratory infection very different from that observed in humans with SARS. The macaque model as it currently exists will have limited utility in the study of SARS and the evaluation of therapies.

Resolution of primary severe acute respiratory syndrome-associated coronavirus infection requires Stat1

Intranasal inhalation of the severe acute respiratory syndrome coronavirus (SARS CoV) in the immunocompetent mouse strain 129SvEv resulted in infection of conducting airway epithelial cells followed by rapid clearance of virus from the lungs and the development of self-limited bronchiolitis. Animals resistant to the effects of interferons by virtue of a deficiency in Stat1 demonstrated a markedly different course following intranasal inhalation of SARS CoV, one characterized by replication of virus in lungs and progressively worsening pulmonary disease with inflammation of small airways and alveoli and systemic spread of the virus to livers and spleens.

Mechanisms of host defense following severe acute respiratory syndrome-coronavirus (SARS-CoV) pulmonary infection of mice

We describe a model of severe acute respiratory syndrome-coronavirus (SARS-CoV) infection in C57BL/6 mice. A clinical isolate of the virus introduced intranasally replicated transiently to high levels in the lungs of these mice, with a peak on day 3 and clearance by day 9 postinfection. Viral RNA localized to bronchial and bronchiolar epithelium. Expression of mRNA for angiotensin converting enzyme 2, the SARS-CoV receptor, was detected in the lung following infection. The virus induced production in the lung of the proinflammatory chemokines CCL2, CCL3, CCL5, CXCL9, and CXCL10 with differential kinetics. The receptors for these chemokines were also detected. Most impressively, mRNA for CXCR3, the receptor for CXCL9 and CXCL10, was massively up-regulated in the lungs of SARS-CoV-infected mice. Surprisingly Th1 (and Th2) cytokines were not detectable, and there was little local accumulation of leukocytes and no obvious clinical signs of pulmonary dysfunction. Moreover, beige, CD1-/-, and RAG1-/- mice cleared the virus normally. Infection spread to the brain as it was cleared from the lung, again without leukocyte accumulation. Infected mice had a relative failure to thrive, gaining weight significantly more slowly than uninfected mice. These data indicate that C57BL/6 mice support transient nonfatal systemic infection with SARS-CoV in the lung, which is able to disseminate to brain. In this species, proinflammatory chemokines may coordinate a rapid and highly effective innate antiviral response in the lung, but NK cells and adaptive cellular immunity are not required for viral clearance.

Clinicopathology of severe acute respiratory syndrome: an autopsy case report

In mid-April 2003, a major outbreak of severe acute respiratory syndrome (SARS) developed in Taiwan. During the outbreak, SARS-associated coronavirus (SARS-CoV) was documented in 346 patients and 73 of them died. Autopsy was performed in 9 of the suspected SARS patients who died during the outbreak, but SARS was the cause of death in only 1 of these patients. Here we report the histological features of this patient and their clinicopathological correlations. The patient, a 36-year-old Indonesian woman, was a caretaker working for a Taiwanese family. She stayed in Taipei Jen-Chi Hospital from April 10 to April 19 to take care of her elderly employer. She developed fever on April 21 and respiratory distress on April 25, and received ribavirin, intravenous immunoglobulin, and steroid. The respiratory distress persisted and worsened, and intubation was performed on April 27. The respiratory condition improved initially after mechanical ventilation, but subcutaneous emphysema and pneumomediastinum developed on May 1. Her condition deteriorated rapidly and she died on May 2, 11 days after the onset of fever. Autopsy was performed on the same day. Histologically, the lungs showed severe diffuse alveolar damage and bronchopneumonia, but no viral inclusion. The spleen and lymph nodes revealed lymphoid depletion and the liver showed microvesicular steatosis. No specific pathological change was seen in the gastrointestinal tract and kidneys. SARS-CoV genome was detected in the nasopharyngeal aspirate and the autopsy lung specimen.

Severe Acute Respiratory Syndrome (SARS) and the GDP. Part I : Epidemiology, virology, pathology and general health issues

SARS is a highly infectious and rapidly progressive form of atypical pneumonia caused by a newly identified strain of coronavirus (SARS-CoV).

Diagnosis is based on clinical findings, epidemiology and exclusion from other pneumonias and is confirmed by a positive seroconversion. There is as yet no definitive treatment protocol.

Symptoms may be similar to other less infective or morbid diseases and over one quarter of those affected have been unsuspecting healthcare workers.

HCW must be familiar with the clinical features and case definitions of SARS to assist in the screening of the disease and prevention of spread.

Surveillance for possible SARS is recommended and control of the epidemic depends on early identification and isolation of carriers and effective infection control and public health measures.

The health profession faces a new challenge with the emergence of a novel viral disease Severe Acute Respiratory Syndrome (SARS), a form of atypical pneumonia caused by a coronavirus termed SARS-CoV. This highly infectious disease has spread through 32 countries, infecting more than 8,400 patients with over 790 deaths in just over 6 months. Over one quarter of those infected were unsuspecting healthcare workers. The major transmission mode of SARS-coronavirus appears to be through droplet spread with other minor subsidiary modes of transmission such as close contact and fomites although air borne transmission has not been ruled out. There is as yet no definitive treatment protocol. Although the peak period of the outbreak is likely to have passed and the risk of SARS in the UK is therefore assessed to be low, the World Health Organisation has asked all countries to remain vigilant lest SARS re-emerges. Recent laboratory acquired cases of SARS reported from Taiwan and Beijing, China are a testimony to this risk. Until reliable diagnostic tests, vaccine and medications are available, control of SARS outbreaks depends on close surveillance, early identification of index cases, quick isolation of carriers and effective infection control and public health measures.

[Pathological changes of lungs in patients with severity acute respiratory syndrome]

OBJECTIVE

To evaluate the progression in morphologic changes of lungs in SARS patients.

METHODS

Four cases of SARS with lung tissue samples available (including one for ultrastructural examination) were enrolled into the study. Histochemical study for VG, Masson, reticulin, orcein, PAS, sirius red stains and immunohistochemical study for vimentin, desmin, smooth muscle actin, HHF-35, CD34, F8, collagen types I and III were also performed.

RESULTS

According to the morphologic changes, lung lesions in SARS were subcategorized into 3 phases: acute exudative inflammation, fibrous proliferation and the final fibrotic stage. Two cases belonged to the acute exudative phase, in which the course was less than 20 days. The principal lesions consisted of acute alveolar exudative inflammation, hyperplasia of alveolar epithelium, necrosis, alveolar hyaline membrane formation, alveolar desquamation and focal fibroplasia. The acute exudative protein was PAS-positive. There was an increase in reticulin fiber formation. The reactive fibroblasts were highlighted by desmin and vimentin. One case belonged to the fibroproliferative stage, in which the course was around 25 days. Major lesions included proliferative interstitial pneumonia with early pulmonary fibrosis. There was also evidence of organizing pneumonia, with an increase in reticulin fiber formation, which had a glomeruloid appearance on special stain. The mesenchymal cells showed either myofibroblastic (which expressed desmin, HHF-35, smooth muscle actin and vimentin) or fibroblastic (which expressed vimentin only) differentiation. Fibroelastosis and fibroplasia was also noted. The remaining case belonged to the fibrotic stage, in which the course was around 75 days. The main features included diffuse fibrosis and honeycomb change, which were highlighted by sirius red stain. Immunohistochemistry showed mainly types I and IV collagen fibers. In all lesions, there was also an increase of number of CD68-positive macrophages.

CONCLUSIONS

The morphologic progression in lungs of SARS patients is characterized by the development of increased fibrosis. The primitive mesenchymal cells, hyperplastic alveolar epithelial cells and macrophages play an important role in the pathogenesis.

Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis

Severe acute respiratory syndrome (SARS) is an acute infectious disease that spreads mainly via the respiratory route. A distinct coronavirus (SARS-CoV) has been identified as the aetiological agent of SARS. Recently, a metallopeptidase named angiotensin-converting enzyme 2 (ACE2) has been identified as the functional receptor for SARS-CoV. Although ACE2 mRNA is known to be present in virtually all organs, its protein expression is largely unknown. Since identifying the possible route of infection has major implications for understanding the pathogenesis and future treatment strategies for SARS, the present study investigated the localization of ACE2 protein in various human organs (oral and nasal mucosa, nasopharynx, lung, stomach, small intestine, colon, skin, lymph nodes, thymus, bone marrow, spleen, liver, kidney, and brain). The most remarkable finding was the surface expression of ACE2 protein on lung alveolar epithelial cells and enterocytes of the small intestine. Furthermore, ACE2 was present in arterial and venous endothelial cells and arterial smooth muscle cells in all organs studied. In conclusion, ACE2 is abundantly present in humans in the epithelia of the lung and small intestine, which might provide possible routes of entry for the SARS-CoV. This epithelial expression, together with the presence of ACE2 in vascular endothelium, also provides a first step in understanding the pathogenesis of the main SARS disease manifestations.

Radiologic pattern of disease in patients with severe acute respiratory syndrome: the Toronto experience

Severe acute respiratory syndrome (SARS) is a transmissible febrile respiratory illness caused by a recently discovered coronavirus. Various patterns of disease progression may be observed that have different implications for the prognosis in those affected by SARS. The appearance of the lungs on chest radiographs of patients with this condition may be normal or may include focal airspace opacity or multifocal or diffuse opacities. Thoracic computed tomography (CT) is more sensitive in depicting SARS than is conventional chest radiography, and CT images obtained in patients with normal chest radiographs may show extensive disease and airspace consolidation. However, because the radiologic appearance of SARS is not distinct from that of other diseases that cause lower respiratory tract infection, early identification of SARS will depend in part on the prompt recognition of clusters of cases of febrile respiratory tract illness. To aid in the differential diagnosis and management of SARS, radiologists must be familiar with the typical clinical and histopathologic findings, as well as the radiologic features of the disease.

Human monoclonal antibody as prophylaxis for SARS coronavirus infection in ferrets

SARS coronavirus continues to cause sporadic cases of severe acute respiratory syndrome (SARS) in China. No active or passive immunoprophylaxis for disease induced by SARS coronavirus is available. We investigated prophylaxis of SARS coronavirus infection with a neutralising human monoclonal antibody in ferrets, which can be readily infected with the virus. Prophylactic administration of the monoclonal antibody at 10 mg/kg reduced replication of SARS coronavirus in the lungs of infected ferrets by 3.3 logs (95% CI 2.6-4.0 logs; p<0.001), completely prevented the development of SARS coronavirus-induced macroscopic lung pathology (p=0.013), and abolished shedding of virus in pharyngeal secretions. The data generated in this animal model show that administration of a human monoclonal antibody might offer a feasible and effective prophylaxis for the control of human SARS coronavirus infection.

Severe acute respiratory syndrome: clinical features, diagnosis, and management

PURPOSE OF REVIEW

In November 2003, a new, life-threatening, respiratory illness named severe acute respiratory syndrome (SARS) arose from Guangdong Province in China. The illness spread across the globe, caused many major outbreaks, and had an overall mortality rate of 11%. The purpose of this review is primarily to review the clinical features, diagnosis, and management of SARS, but also to comment briefly on the epidemiology and pathogen.

RECENT FINDINGS

SARS is caused by a novel coronavirus that primarily affects the lower respiratory tract. It starts with an influenza-like illness characterized by nonspecific, systemic symptoms. This is followed by the rapid development of a non-specific bronchopneumonia associated with lower tract respiratory symptoms, or gastrointestinal symptoms. Most patients recover after a week or 2, but some go on to develop acute respiratory distress syndrome. There is no proven treatment, although cocktails of broad-spectrum antibiotics, antiviral, and immunomodulatory therapy have been tried. Secondary spread can be prevented and outbreaks brought under control provided that staff wear personal protective equipment and pay close attention to good personal hygiene, and patients are isolated. The most urgent needs at present are to develop a vaccine, to develop rapid, inexpensive, accurate diagnostic tests that can give results early in the illness and within a few hours of sampling. Other needs are to investigate which therapies have the lowest adverse event/efficacy ratios.

SUMMARY

Up-to-date knowledge of SARS should help in early detection, isolation of high-risk patients, to reduce mortality and morbidity, and to prevent a new global epidemic arising.

Coronavirus 3CLpro proteinase cleavage sites: possible relevance to SARS virus pathology

Background

Despite the passing of more than a year since the first outbreak of Severe Acute Respiratory Syndrome (SARS), efficient counter-measures are still few and many believe that reappearance of SARS, or a similar disease caused by a coronavirus, is not unlikely. For other virus families like the picornaviruses it is known that pathology is related to proteolytic cleavage of host proteins by viral proteinases. Furthermore, several studies indicate that virus proliferation can be arrested using specific proteinase inhibitors supporting the belief that proteinases are indeed important during infection. Prompted by this, we set out to analyse and predict cleavage by the coronavirus main proteinase using computational methods.

Results

We retrieved sequence data on seven fully sequenced coronaviruses and identified the main 3CL proteinase cleavage sites in polyproteins using alignments. A neural network was trained to recognise the cleavage sites in the genomes obtaining a sensitivity of 87.0% and a specificity of 99.0%. Several proteins known to be cleaved by other viruses were submitted to prediction as well as proteins suspected relevant in coronavirus pathology. Cleavage sites were predicted in proteins such as the cystic fibrosis transmembrane conductance regulator (CFTR), transcription factors CREB-RP and OCT-1, and components of the ubiquitin pathway.

Conclusions

Our prediction method NetCorona predicts coronavirus cleavage sites with high specificity and several potential cleavage candidates were identified which might be important to elucidate coronavirus pathology. Furthermore, the method might assist in design of proteinase inhibitors for treatment of SARS and possible future diseases caused by coronaviruses. It is made available for public use at our website: .

Detection of severe acute respiratory syndrome-associated coronavirus in pneumocytes of the lung

Previous reports have indicated that patients with severe acute respiratory syndrome (SARS)-associated coronavirus infection could develop atypical pneumonia with fulminant pulmonary edema. However, the target cells of SARS viral infection have not been characterized in detail. We report the pathologic findings of the lung in 3 cases of SARS. Chest radiographs at 2 to 3 weeks of infection revealed an atypical pneumonia with pulmonary consolidation, a clinical characteristic of SARS infection. The presence of the SARS virus was determined by nested reverse transcription-polymerase chain reaction (RT-PCR), and the infected cells were identified by in situ hybridization in open-lung biopsy and postmortem necropsy specimens. Expression of SARS virus-encoded RNA was detected in all 3 cases by RT-PCR, and the SARS viral signal was localized in pneumocytes by using in situ hybridization.

The involvement of natural killer cells in the pathogenesis of severe acute respiratory syndrome

By using peripheral blood samples from 221 cases of severe acute respiratory syndrome (SARS), 34 of Mycoplasma pneumoniae infection, and 44 healthy adults, we measured the total number of natural killer (NK) and CD158b+ NK cells (CD158b+ NK) using flow cytometric analysis and calculated the percentage of CD158b+ NK cells. The total number of NK and CD158b+ NK cells and the percentage of CD158b+ NK cells were significantly lower in patients with SARS than in those with M. pneumoniae infection (P < .05 for all) and healthy subjects (P < .01, P < .01, P < .05, respectively); in 72 patients with severe SARS than in 149 with mild SARS (P < .05 for all); and in 174 cases of SARS with anti-SARS coronavirus-specific IgG and/or IgM antibodies than in 47 without antibodies (P < .05, P < .01, P < .01, respectively). There were no significant differences for the 3 values among patients with SARS without anti-SARS coronavirus antibody, patients with M. pneumoniae infection, and healthy subjects. The number of NK cells and the expression of CD158b on the surface of NK cells changed in patients with SARS and correlated with disease severity and the presence of anti-SARS coronavirus-specific antibodies; SARS differed from M. pneumoniae infection in pathogenesis involving NK cells. Monitoring the total number of NK and CD158b+ NK cells and the percentage of CDD158b+ NK cells might aid in differentiating SARS from M. pneumoniae infection.

SARS: clinical virology and pathogenesis

Severe acute respiratory syndrome (SARS) is caused by a novel coronavirus, called the SARS coronavirus (SARS‐CoV). Over 95% of well characterized cohorts of SARS have evidence of recent SARS‐CoV infection. The genome of SARS‐CoV has been sequenced and it is not related to any of the previously known human or animal coronaviruses. It is probable that SARS‐CoV was an animal virus that adapted to human‐human transmission in the recent past. The virus can be found in nasopharyngeal aspirate, urine and stools of SARS patients. Second generation reverse transcriptase polymerase chain reaction assays are able to detect SARS‐CoV in nasopharyngeal aspirates of approximately 80% of patients with SARS within the first 3 days of illness. Seroconversion for SARS‐CoV using immunofluorescence on infected cells is an excellent method of confirming the diagnosis, but antibody responses only appear around day 10 of the illness. Within the first 10 days the histological picture is that of acute phase diffuse alveolar damage (DAD) with a mixture of inflammatory infiltrate, oedema and hyaline membrane formation. Desquamation of pneumocytes is prominent and consistent. After 10 days of illness the picture changes to one of organizing DAD with increased fibrosis, squamous metaplasia and multinucleated giant cells. The role of cytokines in the pathogenesis of SARS is still unclear.

A clinicopathological study of three cases of severe acute respiratory syndrome (SARS)

Aims

The severe acute respiratory syndrome (SARS) caused a large outbreak of atypical pneumonia in Beijing, China from early March 2003. We report the pathological features from three patients who died of SARS.

Methods

Autopsies were performed on three patients who died 9–15 days after the onset of the illness, and the clinical and laboratory features reviewed. Tissue sections were stained with haematoxylin and eosin (H&E), and in situ reverse transcriptase polymerase chain reaction (RT–PCR) on lung sections was performed using SARS coronavirus-specific primers.

Results

The typical gross pathological change in the lungs was diffuse haemorrhage on the lung surface. Histopathological examination revealed serous, fibrinous and haemorrhagic inflammation in most pulmonary alveoli, with capillary engorgement and some capillary microthrombosis. The pulmonary alveoli were thickened with interstitial mononuclear inflammatory infiltrates, diffuse alveolar damage, desquamation of pneumocytes and hyaline-membrane formation; fibrinoid material and erythrocytes were present in alveolar spaces. There were thromboemboli in some bronchial arterioles. Haemorrhagic necrosis and reduced numbers of lymphocytes were observed in lymph nodes and spleen. In situ RT–PCR detected SARS coronavirus RNA in type II alveolar cells, interstitial cells and bronchiolar epithelial cells from all three patients

Conclusions

Severe immunological damage in lung tissue is responsible for the clinical features of SARS.

[Relationship between the severity, course, fatality of severe acute respiratory syndrome patients and the timing of hospitalization]

OBJECTIVE

To study the relationship of timing of hospitalization and the severity, course, fatality of severe acute respiratory syndrome (SARS) patients.

METHOD

1291 hospital records of clinically diagnosed SARS patients with complete data gathered from "2003 Beijing SARS Clinical Database" were analyzed.

RESULTS

SARS cases were categorized into four groups, according to the time of hospitalization after onset of the disease: within 3 days, during day 4 to day 7, during day 8 to day 14 and after day 14. The numbers of cases for each group were 568, 496, 177 and 50 respectively. Data showed that from group 1 to 4, the prevalence rates of major symptoms on the first day of hospitalization were: (1) 9.7%, 16.5%, 23.1% and 24.0% for "feeling chest pain" (P < 0.001), (2) 7.4%, 13.7%, 19.2% and 22.0% for "suffering from breathing obstruction" (P < 0.001), (3) 32.8%, 44.8%, 59.9% and 48.0%, for "coughing" (P < 0.001) and (4) 14.1%, 22.4%, 27.1% and 18.0% for "coughing up phlegm" (P = 0.0002), respectively. The rates of high respiratory frequency (>or= 24 bits/min.) were 11.1%, 15.5%, 22.8% and 25.5% (P < 0.001). The rates of abnormal chest X-ray were 80.3%, 89.0%, 92.3% and 88.9%, respectively (P = 0.002). The average numbers of abnormal lung field (the lung were divided into 6 fields) were 1.7, 1.9, 2.5 and 2.6 (P < 0.001); The numbers of cases receiving continuous oxygen supply treatment were 33.6%, 50.0%, 53.7% and 74.0% (P < 0.001), and the numbers of cases receiving glucocorticosteroids treatment were 28.2%, 35.9%, 53.7% and 62.0% (P < 0.001), respectively. With cases having had chronic baseline diseases prior to SARS infection, the age-standardized fatality rates were 14.9%, 11.7%, 50.0% and 33.9% (P < 0.001), and the average courses of the disease were 30.3, 34.2, 42.9 and 47.5 days (P < 0.001), respectively. In cases without chronic baseline diseases, the age-standardized fatality rates were 5.3%, 9.8%, 9.2% and 8.3% (P = 0.101), and the average courses for each group were 32.4, 35.3, 40.9 and 47.6 days (P < 0.001), respectively.

CONCLUSION

Delayed hospitalization would cause the situation of SARS patient to deteriorate, losing the best chance for treatment and increase case fatality. In terms of control program on SARS, emphasize should be paid on decreasing the panic of patients to the disease so as to get early hospitalization.

Pulmonary pathological features in coronavirus associated severe acute respiratory syndrome (SARS)

BACKGROUND

Severe acute respiratory syndrome (SARS) became a worldwide outbreak with a mortality of 9.2%. This new human emergent infectious disease is dominated by severe lower respiratory illness and is aetiologically linked to a new coronavirus (SARS-CoV).

METHODS

Pulmonary pathology and clinical correlates were investigated in seven patients who died of SARS in whom there was a strong epidemiological link. Investigations include a review of clinical features, morphological assessment, histochemical and immunohistochemical stainings, ultrastructural study, and virological investigations in postmortem tissue.

RESULTS

Positive viral culture for coronavirus was detected in most premortem nasopharyngeal aspirate specimens (five of six) and postmortem lung tissues (two of seven). Viral particles, consistent with coronavirus, could be detected in lung pneumocytes in most of the patients. These features suggested that pneumocytes are probably the primary target of infection. The pathological features were dominated by diffuse alveolar damage, with the presence of multinucleated pneumocytes. Fibrogranulation tissue proliferation in small airways and airspaces (bronchiolitis obliterans organising pneumonia-like lesions) in subpleural locations was also seen in some patients.

CONCLUSIONS

Viable SARS-CoV could be isolated from postmortem tissues. Postmortem examination allows tissue to be sampled for virological investigations and ultrastructural examination, and when coupled with the appropriate lung morphological changes, is valuable to confirm the diagnosis of SARS-CoV, particularly in clinically unapparent or suspicious but unconfirmed cases.

Sputum cytology of patients with severe acute respiratory syndrome (SARS)

BACKGROUND

Severe acute respiratory syndrome (SARS) is a newly described form of atypical pneumonia linked to a novel coronavirus.

AIMS

To review the sputum cytology of 15 patients who fulfilled the World Health Organisation clinical criteria for SARS in an attempt to evaluate whether early diagnosis is feasible with routine sputum examination.

METHODS

All sputum samples from patients with SARS from the four major hospitals in Hong Kong were reviewed; abnormalities were sought in the cellular component, including abnormal numbers and morphology of the component cells compared with those from age matched controls taken over the same period one year ago.

RESULTS

Fifteen sputum samples from patients were compared with 25 control samples. In the patients with SARS, loose aggregates of macrophages were seen more frequently in the sputum. These macrophages frequently showed morphological changes, such as cytoplasmic foaminess, vacuole formation, and nuclear changes (including multinucleation and a ground glass appearance) when compared with the control samples.

CONCLUSIONS

The cytological features of SARS are non-specific, but the observation of any of the described features should prompt further investigations, especially in patients with suspicious clinical features.