History and exam
Key diagnostic factors
Recent travel (within 10 days of the onset of symptoms) to a foreign or domestic location with documented or suspected recent transmission of SARS,[21]Centers for Disease Control and Prevention. Public health guidance for community-level preparedness and response to severe acute respiratory syndrome (SARS) version 2. Supplement B: SARS surveillance. Appendix B1: revised CSTE SARS surveillance case definition. May 2005 [internet publication].
http://www.cdc.gov/sars/guidance/B-surveillance/app1.html
close and prolonged contact with an infected individual,[22]Scales DC, Green K, Chan AK, et al. Illness in intensive care staff after brief exposure to severe acute respiratory syndrome. Emerg Infect Dis. 2003;9:1205-1210.
http://www.ncbi.nlm.nih.gov/pubmed/14609453?tool=bestpractice.com
or working in research laboratories on SARS coronavirus (CoV).[24]Lee N, Hui D, Wu A, et al. A major outbreak of severe acute respiratory syndrome in Hong Kong. N Engl J Med. 2003;348:1986-1994.
http://www.nejm.org/doi/full/10.1056/NEJMoa030685
http://www.ncbi.nlm.nih.gov/pubmed/12682352?tool=bestpractice.com
Rapid onset of a persistent temperature 38°C (100.4°F) or more is an early symptom and sign. Afebrile cases of SARS can occur in older adults.[4]Hui DS, Chan MC, Wu AK, et al. Severe acute respiratory syndrome (SARS): epidemiology and clinical features. Postgrad Med J. 2004 Jul;80(945):373-81.
http://pmj.bmj.com/content/80/945/373.long
http://www.ncbi.nlm.nih.gov/pubmed/15254300?tool=bestpractice.com
[36]Peiris JS, Yuen KY, Osterhaus AD, et al. The severe acute respiratory syndrome. N Engl J Med. 2003;349:2431-2441.
http://www.ncbi.nlm.nih.gov/pubmed/14681510?tool=bestpractice.com
Common in the early respiratory phase (2-7 days from the onset of symptoms) of the disease. Usually non-productive.
Prominent in the prodromal phase of the disease. The patient complains of muscle aches.
Prominent later in the course of the disease (8-12 days from the onset of symptoms). Ranges from mild to severe.
Other diagnostic factors
Usually associated with fever.
Present in the prodromal phase of the disease.
Usually present in the prodromal phase of the disease.
Occurs in 20% to 25% of the patients, usually late in the course of the disease (second week) and together with recurrence of fever. Usually watery without blood or mucus.[11]Peiris JS, Chu CM, Cheng VC, et al. Clinical progression and viral load in a community outbreak of coronavirus-associated SARS pneumonia: a prospective study. Lancet. 2003;361:1767-1772.
http://www.ncbi.nlm.nih.gov/pubmed/12781535?tool=bestpractice.com
A respiratory rate of >20 breaths per minute is present in patients with respiratory distress.
Usually present in patients with fever and/or respiratory distress.
A low oxygen saturation is present in patients with respiratory failure progressing to ARDS.
Non-specific symptom, present in many viral infections. Reported frequency up to 19.5%[1]Christian MD, Poutanen SM, Loutfy MR, et al. Severe acute respiratory syndrome. Clin Infect Dis. 2004;38:1420-1427.
http://cid.oxfordjournals.org/content/38/10/1420.long
http://www.ncbi.nlm.nih.gov/pubmed/15156481?tool=bestpractice.com
May be present early in the course of disease.
May be present, but cough is usually non-productive.
If present, appears late in the course of the disease.
If present, appears late in the course of the disease.
Appears mainly in children and infants, who present with a milder course of the disease with associated rhinorrhoea in 50% of cases.[37]Hon KL, Leung CW, Cheng WT, et al. Clinical presentations and outcome of severe acute respiratory syndrome in children. Lancet. 2003;361:1701-1703.
http://www.ncbi.nlm.nih.gov/pubmed/12767737?tool=bestpractice.com
Non-specific symptom, present in many viral infections. Reported frequency varies from 4.2% to 43%.[1]Christian MD, Poutanen SM, Loutfy MR, et al. Severe acute respiratory syndrome. Clin Infect Dis. 2004;38:1420-1427.
http://cid.oxfordjournals.org/content/38/10/1420.long
http://www.ncbi.nlm.nih.gov/pubmed/15156481?tool=bestpractice.com
Common symptom of many viral infections. Reported frequency up to 10.4%.[1]Christian MD, Poutanen SM, Loutfy MR, et al. Severe acute respiratory syndrome. Clin Infect Dis. 2004;38:1420-1427.
http://cid.oxfordjournals.org/content/38/10/1420.long
http://www.ncbi.nlm.nih.gov/pubmed/15156481?tool=bestpractice.com
Reported frequency 3.5%.[1]Christian MD, Poutanen SM, Loutfy MR, et al. Severe acute respiratory syndrome. Clin Infect Dis. 2004;38:1420-1427.
http://cid.oxfordjournals.org/content/38/10/1420.long
http://www.ncbi.nlm.nih.gov/pubmed/15156481?tool=bestpractice.com
A severe acute neurological syndrome has been reported in patients who developed status epilepticus. SARS coronavirus (CoV) RNA has been detected in cerebrospinal fluid.[38]Lau KK, Yu WC, Chu CM, et al. Possible central nervous system infection by SARS coronavirus. Emerg Infect Dis. 2004;10:342-344.
http://www.ncbi.nlm.nih.gov/pubmed/15030709?tool=bestpractice.com
May be present in older adult patients, who often have an atypical presentation of symptoms.[39]Fisher DA, Lim TK, Lim YT, et al. Atypical presentations of SARS. Lancet. 2003;361:1740.
http://www.ncbi.nlm.nih.gov/pubmed/12767755?tool=bestpractice.com
Present in less than one third of cases. Clinically less severe than would be expected from the radiological findings.[3]Peiris JS, Lai ST, Poon LL, et al. Coronavirus as a possible cause of severe acute respiratory syndrome. Lancet. 2003;361:1319-1325.
http://www.ncbi.nlm.nih.gov/pubmed/12711465?tool=bestpractice.com
Auscultation of the chest may reveal inspiratory crackles.
Auscultation of the chest may reveal bronchial breathing.
Risk factors
History of recent travel, within 10 days of the onset of symptoms, to a foreign or domestic location with documented or suspected recent transmission of SARS raises suspicion of the infection.[21]Centers for Disease Control and Prevention. Public health guidance for community-level preparedness and response to severe acute respiratory syndrome (SARS) version 2. Supplement B: SARS surveillance. Appendix B1: revised CSTE SARS surveillance case definition. May 2005 [internet publication].
http://www.cdc.gov/sars/guidance/B-surveillance/app1.html
Risk of transmission is enhanced by close, prolonged contact with an infected individual.[22]Scales DC, Green K, Chan AK, et al. Illness in intensive care staff after brief exposure to severe acute respiratory syndrome. Emerg Infect Dis. 2003;9:1205-1210.
http://www.ncbi.nlm.nih.gov/pubmed/14609453?tool=bestpractice.com
Transmission in hospitals was a major factor in the amplification of outbreaks, and a significant proportion of those affected were healthcare workers. Healthcare workers, especially those who are exposed to respiratory secretions of a SARS patient (for example, when intubating, suctioning, manipulating oxygen masks, or applying non-invasive ventilation), are at increased risk of infection. In addition, household members in close proximity to a SARS patient, such as those involved in direct patient care, have a higher risk of acquiring SARS.[23]Lau JT, Lau M, Kim JH, et al. Probable secondary infections in households of SARS patients in Hong Kong. Emerg Infect Dis. 2004;10:235-243.
http://www.ncbi.nlm.nih.gov/pubmed/15030689?tool=bestpractice.com
Cases of SARS infection have been reported in research laboratories working on SARS-CoV.[24]Lee N, Hui D, Wu A, et al. A major outbreak of severe acute respiratory syndrome in Hong Kong. N Engl J Med. 2003;348:1986-1994.
http://www.nejm.org/doi/full/10.1056/NEJMoa030685
http://www.ncbi.nlm.nih.gov/pubmed/12682352?tool=bestpractice.com
Providing guidelines for biosafety standards and maintaining continuous vigilance can minimise the risk of such transmission.