Question 13

College Answer

SARS refers to a respiratory syndrome now known to be due to an infection with a novel coronavirus (SARS virus). Both the WHO and the CDC have published criteria for defining cases of SARS. The simpler WHO definition of a suspected case is someone who has fever (>38C), with cough or difficulty breathing, and either close contact with a person diagnosed as SARS or travel/residence (within 10 days of symptoms) in an area with recent local transmission of SARS. The CDC case definition adds radiographic findings in patients with respiratory illness without known aetiology. Patients often have non-specific symptoms (eg. malaise, headache and myalgias) but not gastrointestinal or neurological findings or a rash. SARS is still predominantly a diagnosis of exclusion.
Management: Prevention of disease transmission is crucial. Patients should be isolated in negative pressure rooms, and health care workers should wear masks (eg. N-95 respirator) to prevent airborne and droplet infection, and gowns/gloves/protective eyewear to prevent contact transmission (www.cdc.gov/ncidod/sars/ic.htm). Health care workers should be excluded from work if they develop symptoms within 10 days of exposure to a patient with SARS. No specific antiviral agents have been shown to be beneficial, though a number of antiviral agents and interferon have been tried (usually in combination with corticosteroids). General supportive care is the mainstay of treatment. As this is a diagnosis of exclusion, standard care (including antibiotics) for a severe respiratory illness should be considered. Confirmation of the disease is via antibodies to SARS virus or SARS RNA assays facilitates.

Discussion

SARS is an artifact of the past. However, this question touches upon some important points. It also interrogates the contemporary candidate's familiarity with the SARS coronavirus. The importance of this question may be greater with reference to the emerging MERS-CoV pathogen. All these horrendous viral pneumonias are lumped together into revision chapter, because

• All are viruses without any specific treatment
• All cause severe ARDS
• All of these lifethreatening viral pneumonitis scenarios play out essentially the same.

Diagnostic criteria:

• history of fever
• at least one symptom of lower respiratory tract infection
• pneumonia or ARDS on CXR
• no alternative diagnosis

Supportive history

• recent travel to affected region
• contact with infected people
• pregnancy

Clinical features

• The incubation period lasted 2-10 days
• persistent high fever, chills and rigor
• malaise
• myalgia
• headache
• dry cough
• dyspnoea
• diarrhoea
• The patients did not report much sputum production, and were not complaining of sore throats or rhinorrhoea.

Investigations

• Deranged LFTs, mainly ALT
• Raised LDH
• Raised CK
• Lymphopenia
• Features of DIC

Management:

• Isolation facilities
• Strict droplet and contact precautions (hand hygiene, gown, gloves, N95 masks and eye protection) for healthcare workers
• Avoidance of nebulisers on general wards
• Contact tracing and quarantine isolation for close contact
• supportive ARDS management
• ECMO may be necessary

Centers for Disease Control and Prevention (CDC. "Outbreak of severe acute respiratory syndrome--worldwide, 2003." MMWR. Morbidity and mortality weekly report 52.11 (2003): 226.

Centers for Disease Control and Prevention (CDC. "Outbreak of severe acute respiratory syndrome--worldwide, 2003." MMWR. Morbidity and mortality weekly report 52.11 (2003): 226.

Li, Wendong, et al. "Bats are natural reservoirs of SARS-like coronaviruses." Science 310.5748 (2005): 676-679.

Chan, Paul, Julian Tang, and David Hui. "SARS: clinical presentation, transmission, pathogenesis and treatment options." Clinical Science 110 (2006): 193-204.

Sharif-Yakan, Ahmad, and Souha S. Kanj. "Emergence of MERS-CoV in the Middle East: origins, transmission, treatment, and perspectives." PLoS pathogens 10.12 (2014): e1004457.