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Severe Acute Respiratory Syndrome (SARS): inter-outbreak period

Queensland Health Guidelines for Public Health Units

Revision History

 Version  Date  Changes
 1.0 17 January 2011  Full revision of guideline. 

Introduction

SARS is notifiable to the World Health Organization (WHO) under the International Health Regulations (2005), Class 1.

These guidelines, based on WHO guidelines, are for use in the inter-outbreak period. The case definitions and interventions may be modified by WHO in the event of a re-emergence of SARS.

Infectious Agent

The agent is SARS coronavirus (SARS-CoV), which is similar to animal coronaviruses.

Notification Criteria

Clinical evidence

A person with:
documented fever equal or greater than 38oC
   AND
one or more symptoms of lower respiratory tract illness (cough, difficulty breathing, shortness of breath)
   AND
radiographic evidence of lung infiltrates consistent with pneumonia or Acute Respiratory Distress  Syndrome (ARDS) or autopsy findings consistent with the pathology of pneumonia or ARDS without an identifiable cause
   AND
no alternative diagnosis can fully explain the illness.

Laboratory definitive evidence

  1. Detection of SARS-CoV by nucleic acid testing using a validated method from:
    at least two different clinical specimens (eg. nasopharyngeal and stool)
    OR
    the same clinical specimen collected on two or more occasions during the course of the illness (eg. sequential nasopharyngeal aspirates)
    OR
    two different assays or repeat PCR using a new RNA extract from the original clinical sample on each occasion of testing.
  2. Seroconversion or significant increase in antibody level or fourfold or greater rise in titre to SARS-CoV tested in parallel by enzyme-linked immunosorbent assay or immunofluorescent assay.
  3. Isolation of SARS-CoV
    AND
    Detection of SARS-CoV by nucleic acid testing using a validated method.

Objectives of surveillance in the inter-epidemic period (the SARS alert)

Objectives of the SARS alert are to:

  • provide early warning of the potential recurrence of SARS in order to:
    • rapidly implement appropriate infection control measures in a health care setting
    • expedite diagnosis
    • activate the public health response
  • raise a global alert if indicated.

SARS alert: definition

An individual with clinical evidence of SARS
   AND
one or more of the following epidemiological risk factors for SARS-CoV infection in the 10 days before onset of symptoms:

  • employed in an occupation associated with an increased risk of SARS-CoV exposure (eg. laboratory work with SARS-CoV; exposure to wildlife reservoir)
  • close contact with a person under investigation for SARS
  • history of travel to or residence in an area experiencing an outbreak of SARS

   OR
two or more healthcare workers in the same healthcare unit with clinical evidence of SARS and with onset of illness in the same 10-day period
   OR
three or more persons epidemiologically linked to the same healthcare facility with clinical evidence of SARS with onset of illness in the same 10-day period.

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Notification Procedure

Pathology Laboratories
To notify (i) on receipt of a request for examination, and (ii) upon confirmation of diagnosis by telephone or facsimile.

Attending Medical Practitioner/Medical Superintendents (or Delegates)
To notify urgently on a provisional clinical diagnosis, by telephone or facsimile.

Lab Aspects

A single test result is insufficient for the definitive diagnosis of SARS-CoV infection because both false negative and false positive results are known to occur. 

Have sample(s) marked 'urgent' (if appropriate) and ‘to be forwarded to Virology at QHFSS’. Notify microbiologist on call at Royal Brisbane and Women’s Hospital (or private pathologist if specimen has been processed by private pathology provider) and Queensland Health Forensic and Scientific Services (QHFSS) of incoming sample and level of urgency.

Reporting to NOCS

Report only confirmed cases.

Confirmed case
A confirmed case requires laboratory definitive evidence AND clinical evidence.

Public Health Significance and Occurrence

A severe respiratory infection thought to have originated in the Guangdong Province of China with emergence into human populations in November 2002. The epidemic resulted in 8,098 SARS cases in 26 countries with 774 deaths (crude global case fatality rate 9.6%). The human chain of transmission was broken on 5 July 2003 through intense international effort.

Following the epidemic, three breaches in laboratory safety in late 2003 resulted in one or more further cases of SARS in Singapore, Tapiei and Beijing. A further community outbreak in Guangdong Province in April 2004 was rapidly contained.

The significant public health features of this disease as highlighted by the 2002-2004 epidemic are:

  • its emergence as a zoonotic disease and the role of live animal markets in China
  • capacity for 'superspreading events' in which a small proportion of cases are highly infectious to others
  • high case fatality rate
  • capacity for rapid international spread
  • high rates of transmission in the health care setting with spread to families and contacts of health care workers
  • its potential for major disruption of health care services
  • severe secondary economic and social disruption
  • traditional public health measures including active case finding, case isolation, strict adherence to infection control in health care settings, contact tracing and quarantine, fever monitoring and enhanced surveillance, were successful in controlling the spread of SARS
  • the global response facilitating exchange of information among scientists, clinicians and public health experts was effective in providing information and effective policies and strategies
  • the perception of risk of infection by the general population was far greater than the real risk of infection. Outbreak risk communication and community education were identified as integral to control of the 2002-04 epidemic.

In the inter-epidemic period, the risks for the re-emergence of SARS are:

  • re-emergence from wildlife or other animal reservoirs
  • emergence or introduction from laboratories or via international travel.

While it is very difficult to predict when or whether SARS will re-emerge in epidemic form, WHO requests all countries remain vigilant for the recurrence of SARS and maintain a capacity to detect and respond, should it occur.

Clinical Features

Clinical spectrum and course of SARS is variable, with non-specific symptoms ranging from severe respiratory illness to milder or atypical presentations. Typically, influenza-like illness at onset, with fever, malaise, myalgia, headache, rigors; with or without dry cough and dyspnoea. No specific symptom cluster; fever may be absent. In second week, about 70% develop large volume watery diarrhoea without blood or mucus. Severe cases develop rapidly progressing respiratory distress with about 20% requiring intensive care.  Chest X-ray changes may occur as early as on the 3rd or 4th day of illness, even in the absence of respiratory signs. There are no specific haematological or biochemical findings.

Atypical presentations such as afebrile illness and concurrent sepsis/pneumonia are a particular diagnostic challenge in the elderly. SARS in pregnancy may be associated with increased risk of fetal loss (early pregnancy) and maternal mortality (late pregnancy).

Reservoir

The Himalayan masked palm civet is considered the main source of animal-to-human transmission. Bats may be involved in the chain of transmission amongst animals.

Laboratory sources are a potential reservoir. Laboratory-associated outbreaks of SARS underscore the importance of strict adherence to biosafety procedures and practices for laboratory work with SARS-CoV.

Mode of Transmission

Transmission from wildlife hosts to humans is incompletely understood. 

Person-to-person transmission mostly occurs in the second week of illness and is by respiratory droplets, direct contact with any body fluids (especially respiratory secretions) and fomites. Aerosol-generating procedures pose high risk in the absence of appropriate infection control precautions. Aerosolised or mechanically disseminated sewage is thought responsible for one cluster of the 2003 epidemic.

SARS-CoV is stable in faeces and urine at room temperature for at least 1 to 2 days and up to 4 days in diarrhoeal stools.

Incubation Period

Range 2 to 10 days (average 5 days), rarely longer.

Period of Communicability

Incompletely understood. No evidence for transmission prior to onset of symptoms. Maximum duration of communicability 21 days.

Susceptibility and Resistance

Susceptibility universal. However, children usually have a milder illness.

Management of a SARS Alert

  • A case under investigation will be reclassified as a confirmed case under the circumstances described under Notification Criteria.
  • No case should be downgraded or discarded on the basis of a single negative result whilst awaiting the second result, if clinical and/or epidemiological evidence supports the investigation.
  • A person should be discarded as a case under investigation if an alternative diagnosis can fully explain the illness.

Cases

Investigation
Expedite the diagnosis. Ascertain recent travel, accommodation, school, institution and work history. Identify whether there have been any contacts showing similar symptoms.  Commence contact tracing.   
 
Restriction
Immediately isolate patients under investigation and institute transmission-based precautions (see below).

Counselling
Provide verbal and print information on the clinical picture, transmission and other features associated with SARS, as well as written information on respiratory hygiene and contact precautions.   
 
Reclassification of SARS cases and exclusion criteria

  • A case under investigation will be reclassified as a confirmed case under the circumstances described under Notification Criteria.
  • No case should be downgraded or discarded on the basis of a single negative result whilst awaiting the second result, if clinical and/or epidemiological evidence supports the investigation.
  • A person should be discarded as a case under investigation if an alternative diagnosis can fully explain the illness.

Contacts

Contact Tracing
Yes

Definition
A contact is a person who may be at greater risk of developing SARS because of exposure to a person under investigation for SARS.

Contacts include:

  • household type contacts
  • patients/persons who have shared a room with, or people who have provided care for the person under investigation without appropriate infection control
  • or people who have had direct contact with the body fluids (including respiratory secretions and faeces) of the person under investigation.

Restriction
Inpatient contacts should be isolated or cohorted away from unexposed patients. Place on active fever surveillance.

Exposed health care staff should be placed on active fever surveillance and either cohorted to care for exposed patients or redeployed to non-clinical duties.

Community contacts should be instructed on how to self-monitor for fever (twice daily for ten days from last contact with person under investigation for SARS) and place themselves in isolation pending medical care at onset of fever or other symptom/s.

As there is no evidence for transmission prior to onset of symptoms, quarantine is not warranted.

Investigation
Any contact who develops symptoms should be investigated promptly at an appropriate health-care facility. Inform the facility prior to presentation to minimise the risk of nosocomial transmission.


Prophylaxis
Nil.   

Counselling
Provide verbal and print information on the clinical picture, transmission and other features associated with SARS, as well as written information on respiratory hygiene and contact precautions.
 
Other control measures

SARS Co-V is susceptible to commonly used disinfectants and is destroyed by heating (greater than 55oC.

Summary infection control guidelines for health care facilities

  1. Infection control measures for staff caring for cases under investigation include:
    • standard precautions (ie. hand hygiene)
    • protection from contact with the virus (ie. use of gown, gloves and protective eyewear when in contact with the patient or their environment)
    • protection from droplets containing virus in the air (ie. P2 (N95) mask (respirator) and protective eyewear for attendants when in contact with the patient or their environment)
    • protection from small particles, airborne precautions (ie. an isolation room with negative pressure relative to the surrounding area and use of an P2 (N95 equivalent) mask (respirator) for ALL persons entering the room).
  2. The patient should, if possible, wear a surgical mask if anyone is in the room.
  3. The door to the patient’s room must remain closed, with staff and the patient informed of the need for this.
  4. Patient movement should be restricted. Patients who must leave their rooms should do so only with a surgical mask in place. A surgical mask will capture large wet particles near the nose and mouth of the wearer, thus preventing the spread from the wearer to others.
  5. Avoid the use of nebulisers, chest physiotherapy, bronchoscopy, gastroscopy, or any intervention that may disrupt the respiratory tract (see guidelines on aerosol generating procedures below).
  6. Surgical masks should be placed over nasal oxygen prongs.
  7. Use disposable equipment wherever possible in the treatment and care of patients with SARS and dispose of appropriately in the clinical waste. If devices are to be reused, they should be reprocessed in accordance with manufacturers' instructions.

Accommodation should be allocated as follows in descending order of preference.

  1. Single negative pressure room/respiratory isolation room with the door closed.
  2. Single room with own bathroom facilities and the door closed, air conditioning turned off and windows (away from public places) opened, if possible.
  3. Avoid nursing these cases together wherever possible. If not possible, rooms should only be shared by cases at the same stage of investigation.

Community outbreaks/epidemics

Establish an incident management team and prepare to scale up the response in accordance with incident management plans.

Preventive measures

Preparedness planning for the detection, investigation, containment and control of unexplained clusters of acute respiratory disease.

Feedback

Conduct incident debriefing with relevant stakeholders and prepare a summary report for the Communicable Diseases Branch.

Summary

These guidelines are aimed at the early detection and investigation of individuals with clinically apparent SARS-associated coronavirus infection, in the inter-epidemic period (ie. in the absence of a global alert on SARS). They are based on the most common clinical features and on the requirements of laboratory diagnosis. 

This document should be used in conjunction with:

  • the WHO guidelines for the global surveillance of SARS
  • the current Australian infection control guidelines.

References

Commonwealth Department of Health and Ageing and Communicable Diseases Network Australia. Interim Australian Infection Control Guidelines for Severe Acute Respiratory Syndrome (SARS). Section 2 Health Care Facilities. 25 April 2004. Available at: http://www.health.gov.au/internet/main/publishing.nsf/Content/AF6930AC75BDE030CA256F19000539B6/$File/2_icg.pdf

Heymann D L (Ed) 2008. Control of Communicable Diseases Manual, 19th Edition. American Public Health Association, Washington.

World Health Organization Department of Communicable Disease Surveillance and Response. WHO guidelines for the global surveillance of severe acute respiratory syndrome (SARS). October 2004. Available at: http://www.who.int/csr/resources/publications/WHO_CDS_CSR_ARO_2004_1.pdf

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Last updated: 20 January 2011