SARS, MERS and the Coronaviruses

Reviewed and revised 15th August 2013

OVERVIEW

  • There are at least 6 coronaviruses that cause infections in humans: alpha coronaviruses 229E and NL63 and beta coronaviruses OC43, HKU1, and SARS-CoV; and the new MERS-CoV
  • Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) are novel coronaviruses that cause severe viral pneumonia in humans
  • Most coronavirus infections are mild respiratory tract infections

SARS

  • caused by a coronavirus called SARS-CoV
  • originated in Asia in 2003 and led to a global epidemic, with cases reported from 29 countries
  • 11% fatality rate
  • no cases since 2003
  • originated in the horseshoe bat, with the civet cat an intermediate host

WHO Case Definition:

  • fever (>38 C)
  • cough or SOB
  • contact history or travel/residence in last 10 days from an area with recent local transmission of SARS

CDC Case Definition:

  • adds radiological findings in patients with respiratory illness without aetiology

MERS

  • first reported in Saudi Arabia in 2012
  • caused by a coronavirus called MERS-CoV
  • most confirmed cases develop severe acute respiratory illness (fever, cough, and shortness of breath)
  • about 50% mortality
  • so far all the cases linked to countries in or near the Arabian Peninsula
  • spread through close contact and has not (yet) been found to spread in a sustained way in communities
  • The situation is still evolving!

TRANSMISSION

  • droplet transmission to upper respiratory tract; SARS may have also had airbourne spread
  • SARS-CoV binds to CD209L (L-SIGN) and ACE-2, two functional receptors on the respiratory tract epithelium
  • viral replication and invasion in epithelial cells

CLINICAL MANIFESTATIONS

SARS

  • 7 day incubation period
  • initial prodrome, characterized by fever with or without rigors, malaise, headache, and myalgia
  • Some also have mild respiratory symptoms or nausea and diarrhea
  • respiratory phase occurs 8 days after onset of fever; 45% hypoxemia, 20% ARDS and requiring mechanical ventilation
  • no rash
  • diagnosis of exclusion

INVESTIGATIONS

SARS

  • absolute lymphopenia
  • RT-PCR from nasopharyngeal specimens
  • antibodies to SARS virus
  • SARS RNA assays (can be detected in stools from week 2 on)
  • CXR: ground-glass opacifications, unilateral and bilateral infiltrates, pneumomediastinum without preceding intubation of positive pressure = characteristic sign

MANAGEMENT

Goals

  1. prevention of transmission
  2. supportive care
  3. may need activation of disaster plan to control outbreak

Infection control

  • isolation
  • negative pressure room
  • PPE: N-95 masks, gowns, gloves, eye wear
  • health care workers should be excluded from work if they develop symptoms within 10 days of exposure to a patient with SARS
  • activate disaster plan if indicated

Specific therapy

  • no specific antiviral agents have been shown to be beneficial
  • consider antibiotics if uncertain diagnosis or suspected super-infection
  • corticosteroids, immunoglobulin and interferon were ineffective for SARS

Supportive care and monitoring

  • protective lung ventilation with low tidal volumes

Seek and treat complications


References and Links

Journal articles

  • Booth CM, Stewart TE. Severe acute respiratory syndrome and critical care medicine: the Toronto experience. Crit Care Med. 2005 Jan;33(1 Suppl):S53-60. PMID: 15640680.
  • Centers for Disease Control and Prevention (CDC). Update: Recommendations for Middle East Respiratory Syndrome Coronavirus (MERS-CoV). MMWR Morb Mortal Wkly Rep. 2013 Jul 12;62(27):557. PMC4604945
  • Hawryluck L, Lapinsky SE, Stewart TE. Clinical review: SARS – lessons in disaster management. Crit Care. 2005 Aug;9(4):384-9. PMC1269424.
  • Memish ZA, Zumla AI, Assiri A. Middle East Respiratory Syndrome Coronavirus Infections in Health Care Workers. N Engl J Med. 2013 Aug 7. PMID: 23923992.
  • Poulakou G, Pérez M, Rello J. Severe acute respiratory infections in the postpandemic era of H1N1. Curr Opin Crit Care. 2012 Oct;18(5):441-50. PMID: 22820154.

FOAM and web resources


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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