How Does One Get Infected with SARS

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How Does One Get Infected with SARS?

• Jaime C. Montoya, MD, MSc, FPCP, FPSMID
• May 8, 2003

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The terror of the unknown is seldom better
displayed than by the response of a population to
the appearance of an epidemic, particularly when
the epidemic strikes without apparent cause.
Edward Kass, 1977
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Etiology of SARS

• A new member of Corona virus isolated in 50 to
  60 of cases identified as the causative agent
• Duration of survival in environment unknown
  other Corona viruses known to survive for up to 4
  hours

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Characterization of the SARS Virus

• Based on studies done by WHO network of
  collaborating labs
• Stable in feces and urine at room temperature for
  at least 1-2 days
• More stable (up to 4 days) in stool from diarrhea
  patients (higher pH than normal stool)

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Characterization of the SARS Virus

• Based on studies done by WHO network of
  collaborating labs
• Virus loses infectivity after exposure to
  different commonly used disinfectants and
  fixatives (used in labs)

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Virus Survival in Cell Culture

• Only minimal reduction in virus concentration
  after 21 days at 4 C and -80 C
• Heat at 56 C kills the SARS virus for 15 mins
• Indicative that virus is more stable than the
  known human coronavirus under these conditions

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Characterization of the SARS Virus

• Dose of virus needed to cause infection remains
  unknown
• Further studies needed before firm conclusions
  about the role of fecal-oral transmission can be
  made
• Spread by infected droplets remain the most impt
  mode of transmission
• Shedding of virus in feces, respiratory
  secretions and urine is now well established

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Cluster Study of Mechanism of spread

• Cluster of gt320 simultaneous cases among
  residents of the Amoy gardens housing estate
• Contamination with sewage has a role
• 66 of cases presented with diarrhea as a symptom
  compared with 2-7 of cases in other outbreaks
• Cases were linked to visits to a high floor in
  the hotel

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SARS transmission

• SARS can be transmitted from person to person by
  droplet infection.
• SARS cases, when they cough, can spread droplets
  with the infective organism to a distance of
  approximately one meter or three feet.
• SARS can not be transmitted by mosquitoes or
  other insects and animals.

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SARS transmission

• Contaminated hands, clothes, equipment the
  environment may also be important

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Clinical picture in SARS patients
Recovery approx 90
Acute respiratory distress syndrome approx 10
Infectivity
None /very low
Low
Very high
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Prince of Wales Hospital, Hong Kong

• Clinical features of 138 secondary tertiary
  cases
• Fever 100 (high grade, persistent)
• Chills/rigor 73
• Myalgia 61
• Dry cough 57
• Headache 56
• Dizziness 43

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Laboratory findings
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Chest x-ray appearances

• Opacities are predominantly found in the lower
  lung zones
• Pleural effusions not seen
• Could be rapidly progressive and might need twice
  daily CXRs

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• Hospitals and major health facilities should
  prepare a strategy for the triage, isolation, and
  barrier nursing of a patient(s) with SARS

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Enhanced Surveillance for SARS

• Sensitive system in place for ID of SARS cases ?
  isolation/barrier nursing ? limit local spread
• Countries without previous SARS cases should use
  a more sensitive suspect case definition ? early
  implementation or control measures
• System for verifying or dispelling rumours
  anecdotal accounts of SARS cases
• Early notification of National/WHO authorities

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SARS Suspect Case Definition

• High fever (gt38OC)
• AND
• Cough, shortness of breath or difficulty of
  breathing
• AND
• 1. Close contact within 14 days of onset of
  symptoms, with a person diagnosed with SARS
• or
• 2. History of travel to SARS area within 14 days
  of onset of symptoms

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Probable SARS case

• Suspect case plus pneumonia or respiratory
  distress syndrome (RDS)
• OR
• Suspect case unexplained respiratory illness
  leading to death with autopsy finding of RDS
  without an identifiable cause.

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SARS case requiring public health action
enhanced sensitivity definition for previously
unaffected and low risk, high support countries

• A person presenting with a history of
• high fever (gt38oC)
• AND one or more of the following
• close contact within 14 days of onset of
  symptoms, with a person who has been diagnosed
  with SARS
• history of travel within 14 days of onset of
  symptoms, to an area in which there are reported
  foci of transmission of SARS

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Suggested algorithm for contacts/travellers
Does the patient have a recent history of travel
to an affected area or close contact with a SARS
patient
Has fever (gt38oC) developed within 14 days of
leaving affected area, or contact with known
SARS patient?
ISOLATE AND INVESTIGATE Treat as possible SARS
case isolate/barrier nursing implement
local SARS plan notify local health authorities
and WHO country representative about possible
SARS case
Yes
Yes
No
No
No
Is the patient still within known incubation
period for SARS (14 days) following
travel/contact with SARS case?
Yes
Give information about personal surveillance for
fever during incubation period treat nonSARS
medical illness
Provide information about SARS treat nonSARS
medical illness
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INFECTION CONTROL in SARS
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Overall Aim of Infection Control Measures in SARS

• Minimize probability of transmission to
  healthcare workers, family and the public

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At a glance Essential Principles of Infection
Control

• Isolation and avoidance of unnecessary contact
• Use of personal protective equipment (PPE) for
  all in close proximity
• Strict personal hygiene
• Masking of patient to reduce respiratory spread

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Infection Control Precautions

• Avoid crowded places and areas where ventilation
  is poor and air exchange is found to be
  inadequate
• Cover the nose and mouth whenever you sneeze or
  cough. After sneezing or coughing, always wash
  your hands with soap and water or alcohol-based
  sanitizers
• Avoid touching the face (esp the eyes, nose and
  mouth) after close contact with other people
• Do not share eating utensils

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Infection Control Precautions

• Always wash your hands with soap and water before
  and after meals and after contact with other
  people. Alcohol based hand sanitizers may be
  used for as long as visible soiling of hands is
  not present.
• You must wear a mask, preferably an N95, when
  visiting high risk areas (ER, ICU, respiratory
  units)
• Masks should be used properly to ensure its
  optimal performance as a form of protective
  equipment

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Infection Control Precautions

• Unsure that air-conditioners are cleaned and well
  maintained
• Always maintain a health lifestyle, which
  includes eating a balanced diet, enough rest and
  exercise and smoking and drinking in moderation.
• This will ensure the maintenance of an adequate
  and healthy immune system as a line of defense
  against infection.

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Public Awareness

• Information is your ally
• Stay informed and keep the public informed
• Check DOH and WHO websites every day

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Thank You Very Much!
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TRIAGE GUIDELINES
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Flow Chart for the Screening of SARS Suspect
Probable Cases
Travel history to identify SARS areas or close
contact w/ SARS suspect
(-) fever () respiratory symptoms
() fever () respiratory symptoms
(-) fever (-) respiratory symptoms
() fever (-) respiratory symptoms
SARS SUSPECT Admit to holding area
while awaiting transfer to a DOH- identified
hospital for SARS cases. (See Flowchart 1).
See Flowchart 4.
See Flowchart 2
See Flowchart 3.
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FLOWCHART 4 Screening of Patients with Travel
History / Contact within 14 days without Symptoms
seen at Ambulatory Care ER Settings
Patients with travel history/contact without
symptoms
Fill out contact form
Provide hotline numbers and advice regarding
personal surveillance which includes monitoring
for fever and respiratory symptoms.
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FLOWCHART 1 Screening of Patients with Travel
History / Contact within 14 days with Fever
Respiratory Symptoms seen at Ambulatory Care ER
Settings
Patients with fever and respiratory symptoms
SARS SUSPECT Admit to holding area
while awaiting transfer to a DOH identified
hospital for SARS cases. (See Flowchart 1).
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FLOWCHART 3 Screening of Patients with Travel
History / Contact within 14 days with Cough but
without Fever seen at Ambulatory Care ER
Settings
Patients with travel history/contact with cough
but without fever
Fill out contact form
Treat as non-SARS cases and manage accordingly.
Provide hotline numbers and advice regarding
personal surveillance which includes monitoring
for fever and worsening respiratory symptoms
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Flowchart 2 Screening of Patients with Travel
History/Contact within 14 days with fever but
without Cough seen at Ambulatory Care ER
Settings
Travel history to identify SARS areas or close
contact w/ SARS suspect
Fever gt7 days
Fever lt 7 days
Do chest x-ray
Admit to designated isolation area. Do Chest
x-ray.
POSSIBLE SARS Refer to DOH for further monitoring
of onset of respiratory symptoms and further
work-up
Treat as non-SARS case give advice.
Pneumonia infiltrates on chest x-ray?
Pneumonia infiltrates on chest x-ray?
NO
NO
YES
YES
PROBABLE SARS Refer to DOH identified facilities
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INITIAL DIAGNOSTIC EVALUATION

• CBC
• ALT, AST, CK, LDH
• Blood culture sensitivity
• Sputum GS, CS
• Chest x-ray
• Pulse oximetry
• Save specimens (serum, respiratory) for
  additional tests

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SARS LABORATORY TESTS

• Serology
• Enzyme immuno-assay
• Indirect fluorescent antibody assay
• RT-PCR in serum, stool, nasal secretions
• Electron microscopy
• Viral culture

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Treatment of SARS

• Efficacy of ribavirin and other antiviral agents
  against coronavirus is unknown
• In-vitro preliminary results indicate that
  ribavirin concentrations that inhibit
  ribavirin-sensitive viruses do not inhibit
  replication or cell-to-cell spread of the novel
  coronavirus (MMWR April 11, 2003)
• Ribavirin is a known teratogen, may cause severe
  hemolytic anemia
• More tests clinical information on outcome of
  patients treated with ribavirin is needed

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• Dose of ribavirin 400 mg IV q 8h for 14 days
• Steroids
• IV methylprednisolone is recommended
• 3 mg/kg/d for 5 days, then
• 2 mg/kg/d for 5 days, then
• 1 mg/kg/d for 5 days, then
• taper off with oral prednisolone

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The Global Challenge of SARS

• If we are extremely lucky, the epidemic will be
  curtailed, develop a seasonal pattern . . . . or
  evolve more slowly . . . If the virus moves
  faster than our scientific, communication
  control capacities we could be in for a long,
  difficult race. In either case, the race is on.
  The stakes are higher, and the outcome cannot be
  predicted.

J. Geberding, CDC 2003
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