SEVERE ACUTE RESPIRATORY SYNDROME (SARS)

Introduction

Characteristics

Transmission

Methods for Monitoring in the Environment

Methods for Measuring Human Exposure

Strategies for Preventing or Controlling Exposure


Harmful Effects

Absorption, Distribution and Metabolism

Sites of Toxicity

Biomarkers of Disease

Molecular Mechanisms of Action

Risk Assessment/Management

5103 Home

CHARACTERISITICS OF SARS

Characteristics of SARS-Associated Coronovirus (SARS-CoV)

The SARS-associated coronavirus is physically a typical coronavirus. Their shape – A core of genetic material surrounded by a spherical protein shell, characterizes Coronaviruses. The protein shell is covered with extruding surface proteins that create a halo, or corona, when viewed with electron micrography.







Escors D, Camafeita E, Ortego J, Laude H, Enjuanes L, Organisation of Two Transmissible Gastroenteritis Coronavirus Membrane Protein Topologies within the Virion and Core. Journal of Virology Dec 2001: 12228 – 12240

Stability and Resistance of the SARS-Associated Coronavirus

Virus survival in stool and urine:

  • Virus is stable in feces (and urine) at room temperature for at least 1-2 days.
  • Virus is more stable (up to 4 days) in stool from diarrhea patients (which has higher pH than normal stool).

Disinfectants:

  • Virus loses infectivity after exposure to different commonly used disinfectants and fixatives.

Virus survival in cell-culture supernatant:\

  • Only minimal reduction in virus concentration after 21 days at 4°C and -80°C.
  • Reduction in virus concentration by one log only at stable room temperature for 2 days. This would indicate that the virus is more stable than the known human coronaviruses under these conditions.
  • Heat at 56°C kills the SARS coronavirus at around 10000 units per 15 min (quick reduction).

Fixatives (for use in laboratories only):

  • SARS virus fixation (killing) on glass slides for immunofluorescence assays in room temperature does not kill virus efficiently unless the acetone is cooled down to -20oC.

Characteristics of the Disease

Incubation period:

  • Generally 2-7 days, can be up to 10 days

SARS Symptoms:

  • Begins with a high fever (>100.4ºF, >38.0ºC)
  • Fever can be accompanied by chills, rigors, headache, malaise, and myalgia
  • Mild respiratory symptoms may be present at onset of illness
  • After 3-7 days, onset of lower respiratory symptoms occurs including a dry, nonproductive cough or dyspnea which may be accompanied by or progress to hypoxemia
  • Most patients develop pneumonia
  • Diarrhea is typically absent but may occur in some cases
  • Severity of illness is highly variable ranging from mild illness to death

In many patients the respiratory phase is characterized by early focal interstitial infiltrates progressing to more generalized, patchy, interstitial infiltrates.

Figure 1. Chest radiographs of index patient with severe acute respiratory syndrome (SARS). a, day 5 of symptoms; b, day 10; c, day 13; d, day 15.