Information about SARS (Severe Acute Respiratory Syndrome)
CURRENT SARS/AVIAN INFLUENZA (H5N1) AFFECTED AREAS
Increased vigilance is recommended for the surveillance, recognition,
reporting and prompt investigation of patients with unexpected
outcomes of severe influenza-like illness (severe ILI*) who are
linked to
H5N1 avian flu-affected areas.
For specific recommendations regarding screening, laboratory
investigations and reporting, please consult your local or provincial/territorial
health authorities.
INFORMATION ABOUT SARS
There are currently no cases of Severe Acute Respiratory Syndrome (SARS)
anywhere in the world. This site is being maintained for historical
purposes only.
ETIOLOGIC AGENT
On April 16, 2003 researchers around the world established a
hitherto unknown virus as the cause of SARS. The new coronavirus
has been named by WHO and member laboratories as "SARS-CoV
Virus" [image
of virus]. Thirteen laboratories worked on meeting Koch's
postulates, necessary to prove disease causation. Koch's postulates
stipulate that to be the causal agent, a pathogen must meet four
conditions: it must be found in all cases of the disease, it must
be isolated from the host and grown in pure culture, it must reproduce
the original disease when introduced into a susceptible host (in
this case, monkeys), and it must be found in the experimental
host so infected. Credit for the coronavirus findings, which definitively
pinpoints the cause of SARS, is attributed to the 13 laboratories,
working in conjunction with WHO. This discovery now enables scientists
to concentrate on developing diagnoses kits, treatments and, eventually,
the possibility of a vaccine. [ref:
WHO, 16 April 2003 ]
There is some evidence that the SARS virus originated in animals
and crossed into humans, and work is continuing to confirm this.
Animal testing has shown that co-infection with other viruses
(e.g. metapneumovirus) does not affect the virulence of the SARS
virus or act in a symbiotic fashion with it, as earlier suspected.
Many animal species appear to be able to carry the SARS virus.
[WHO] In a recent seroprevalence study carried out in Guangdong
Province in China (the "birthplace" of SARS), "serologic
evidence suggests that asymptomatic infection with SARS-CoV or
an antigenically related virus occurred in Guangdong Province.
Seroprevalence of IgG antibody to SARS-CoV was substantially higher
among traders of live animals than among persons in control groups,
consistent with the hypothesis that SARS-CoV crossed the species
barrier from animals to humans. The results are consistent with
preliminary determinations of a joint research team from China's
Ministry of Agriculture and Guangdong Province, which found that
sequences of coronavirus detected by polymerase chain reaction
in bats, monkeys, masked palm civets, and snakes were identical
to or similar to those of human SARS-CoV isolates. In addition,
a joint study by Shenzhen CDC and Hong Kong University determined
that the sequence of coronavirus isolated from masked palm civets
is 99 percent identical to human SARS-CoV. These determinations
appear consistent with the hypothesis that an animal reservoir
exists for SARS-CoV or an antigenically related virus; however,
the findings are not sufficient to identify either the natural
reservoir for SARS-CoV or the animal(s) responsible for crossover
to humans. This report provides indirect support for the hypothesis
that SARS-CoV might have originated from an animal source and
identifies multiple animals for further study". [ref:
ProMed Oct. 16, 2003].
SYMPTOMS OF SARS [ref: WHO]
Symptoms of the illness, in order of observed frequency, include
high fever, non-productive cough, shortness of breath, malaise,
diarrhea, chest pain, headache, sore throat, myalgias and vomiting.
Lymphopenia, elevated LDH levels, elevated AST levels and elevated
creatine phosphokinase levels have also been reported [ref: Health
Canada]. About 10% of patients decline around day 7 and require
mechanical assistance to breathe. Symptoms appear to be worse
in the second week of illness and onwards.
TRANSMISSION [WHO]
The primary mode of transmission of the SARS virus is direct
mucous membrane (eyes, nose, and mouth) contact with infectious
respiratory droplets and/or through exposure to fomites
(objects contaminated with infected material). SARS does
not appear to be airborne. Most of the data have
been consistent with transmission through
large droplets or body fluids. Aerosol transmission
cannot be totally discounted, but if it occurs it is uncommon.
If the causative organism had been readily transmissible by
aerosol, many more cases would have been expected, especially
in the countries where transmission has slowed or never started. Aerosolizing
procedures in hospitals (such as nebulization), and other events
that promote aerosolization of infectious respiratory droplets
or other potentially infectious materials (such as faeces or
urine) in hospitals or other settings, may amplify transmission.
The incubation period ranges
from 2 to 10 days, with a mean of 4-6 days and a median of 4-5
days. The minimum reported incubation period was 1 day and the
maximum was 14 days. It is still unclear whether the route of
transmission influences the incubation period.
Transmission efficiency appears to have been greatest from
severely ill patients or those experiencing rapid clinical deterioration,
usually during the second week of illness. Data from Singapore
showed that few secondary cases occured
when symptomatic cases were isolated within 5 days of illness
onset.
Viral shedding of the SARS
virus was relatively low during the initial phase of illness,
and peaked at about day 10 of illness in respiratory specimens.
Virus shedding in stool began later than in respiratory secretions,
with most samples showing positive PCR by day 12-14 and then
declining. This made testing difficult in the early stages
of the disease.
Some persons appeared to be "super-shedders",
with very high viral loads that resulted in transmission. There
is presently no evidence to suggest that disease transmission
occurs prior to the onset of symptoms in a suspected or probable
case of SARS [Health Canada].
In Hong Kong there were some patterns of infection that are
most easily explained by environmental
transmission.
Evidence suggests that the virus survives in faeces and
urine at room temperature for at least 1-2 days, and appears
to be more stable in stool from patients with diarrhoea (up
to 4 days), possibly related to the increased pH. The SARS virus
survives freezing. Heat at 56°C for 15 minutes kills the virus,
as does exposure to many common disinfectants and fixatives
[WHO].
The index case in Ontario was an individual who travelled to
Hong Kong and stayed at the Metropole Hotel, where a cluster of
SARS cases was subsequently identified [ref: MMWR Vol 52, No.
12, March 28, 2003]. Two clusters of cases in Toronto represented
community transmission resulting
from late diagnosis of cases within a small religious group and
persons who attended a funeral.
The experience in Canada illustrates that highly developed countries
can be vulnerable to transmission from imported cases of SARS,
especially in hospitals. If the infection is not recognized early
and appropriate infection control precautions put in place, extensive
transmission can occur. Early detection and ongoing surveillance
appears to be the main reason for the lack of transmission from
cases in B.C. and the U.S. Those most at risk seem to be family
members (19% of cases) and healthcare
workers (74% of cases) who have close contact with
symptomatic cases. Travel-related cases
are few (7%). It is worth noting that there were no reported secondary
cases from 2 hospitalized Canadian SARS cases where family members
were not permitted to visit and healthcare workers adhered to
strict infection control precautions.
Other Sources of Transmission: WHO
is aware of concern over the possibility that SARS may be caused
by contact with animals. WHO is therefore working closely with
the Food and Agriculture Organization of the United Nations (FAO)
and the Office International des Epizooties (OIE), to determine
whether there is any evidence to suggest that SARS-related disease
has occurred in animals. WHO, FAO and OIE have reviewed reports
received regarding SARS transmission. To date there is no epidemiological
information to suggest that contact with goods, products, or animals
shipped from SARS-affected areas has been the source of SARS infection
in humans.
2003 CASE COUNT
(cumulative cases) BASED ON WHO DEFINITIONS
By December 31, 2003 the World Health Organization (WHO) received
reports of 8098 probable cases (774 deaths) of Severe Acute Respiratory
Syndrome (SARS), an atypical pneumonia due to one or more viruses. The
first documented case occurred on November 16, 2002 (China).
The last reported case in the 2003 epidemic occurred on July
13, 2003 (U.S.). Healthcare workers accounted for 21% of all
cases. The world case fatality rate for
probable cases was 9.6%. Twenty-six countries reported
cases, with the majority of cases occurring in China, Hong Kong,
Singapore, Taiwan, Viet Nam, Canada and the U.S. [see epidemic
curves]. [ref: World Health Organization]. For a summary
of cases by country refer to the WHO
summary table.
In the U.S. there were 8 confirmed cases, 19 probable cases
and 137 suspect cases reported in 2003. (total 164 cases). No
deaths were reported in the U.S. [ref: Centers
for Disease Control and Prevention].
In Canada there were 251 probable
cases (247 cases in Ontario, 4 cases in British
Columbia), with 44 deaths (43
probable, 1 suspect). In addition there were 187
suspect cases (128 in Ontario, 46 in B.C., 6 in
Alberta, 4 in PEI, 2 in New Brunswick and 1 in Saskatchewan).
The case
fatality rate in Canada was estimated at approximately 17.1%
of probable cases (10.0% of probable and
suspect cases). Most of the case fatalities occurred in patients
with underlying illness, and nearly all were elderly patients
with the average age being 71 years. There
have been no new cases of SARS in Canada since June 12, 2003. [ref:
Health Canada].
There were a total of 136 probable cases and 27 deaths in the
first Ontario cluster and 111 probable cases with 17 deaths in
the second Ontario cluster in 2003.
The Ontario Experience
In Ontario, Public Health officials closed two hospitals in
Toronto in March, 2003. The initial cases in Toronto were either
travellers from Asia or healthcare workers who had unprotected
contact with initial cases before they were aware of SARS. On
March 26, the Premier of Ontario declared SARS to be a provincial
emergency. It was also made a reportable virulent communicable
disease in Ontario. On March 27, 2003 additional measures were
put into place in the Greater Toronto Area and Simcoe County,
which included limiting visitors to hospitals, restricting patient
visits to hospitals, suspending volunteer programs and suspending
patient transfers into the city hospitals as well as transfers
between health care facilities in the area. On March 31 these
measures were extended to all hospitals in Ontario. On May 16,
2003 many of these restrictions were lifted as there had been
no new cases of SARS in Ontario since May 4, 2003.
On May 24, health authorities in Canada informed WHO that two
clusters of cases of respiratory illness in Toronto were undergoing
investigation for respiratory illness, including pneumonia. One
cluster involved 5 cases and a second cluster involved 26 cases,
including 10 health care workers. One patient undergoing investigation
had been linked to both clusters. There was no evidence of widespread
public transmission of SARS and all of the new cases under investigation
were linked to the original cluster of cases. Hospitals in the
Greater Toronto Area were asked to return to heightened infection
control protocols in their Emergency departments. These precautions
have now been relaxed and there are no current travel advisories
due to SARS. For the CCWR report on this second cluster see CCDR
Preview, 13 June 2003.
SARS in Laboratory Workers [August/03,
December/03]
On August 26, 2003 the World
Health Organization confirmed a single case of SARS in a laboratory
worker in Singapore, the first case since the end of the world
pandemic of SARS. Acquisition appeared to have been occupational
[WHO
Website]. On December 11, 2003 a
laboratory worker in Taiwan developed symptoms of SARS following
laboratory exposure [WHO
Website]. There was no transmission related to either of
these cases. Laboratory workers can find guidelines for working
with SARS in laboratories in the Laboratory Information section
of this page (under SARS LINKS). For
more information on the Taiwan case:
Post-epidemic SARS in Guangdong, China
[December/03 - January/04]
On December 20, 2003 a 32–year–old television producer
from Guangzhou, China was hospitalized and placed on isolation
with symptoms of pneumonia (onset December 16). Laboratory tests
indicated the possibility of SARS CoV infection. Further testing
confirmed SARS. All contacts were quarantined and there were
no additional cases. For more information on this case:
Since then, three further cases (confirmed in
a female restaurant worker and a physician, probable SARS
in a business man) surfaced in Guangzhou. All four cases were
unrelated. There have been no secondary
cases of SARS. For more information:
Post-epidemic SARS in Beijing, China
[April/04]
Confirmed Cases: On
March 25, 2004 a 26-year-old female laboratory researcher (who
had been working with the SARS virus) developed symptoms compatible
with SARS and was hospitalized in Beijing. The researcher's mother,
who also assisted in her care, fell ill on April 8 and died on
April 22. On April 7, 2004 a 20–year–old nurse who
had been caring for the researcher was hospitalized and a few
days later was placed in intensive care with SARS-like symptoms
(onset April 5). Five contacts of the nurse (her mother, father,
aunt, as well as a patient sharing a ward with the nurse and
the patient's daughter who accompanied the patient) subsequently
developed symptoms (onset April 16 to 19). The ninth case was
a 31-year-old male laboratory researcher (same laboratory as
the above), who developed symptoms on April 17 and was hospitalized
on April 22. These 9 cases were confirmed as caused by the
SARS coronavirus by the World Health Organization following extensive
review. There have been no new cases
since April 19, 2004.
For more information on these cases:
The Public Health Agency of Canada has provided the following
documents:
EPIDEMIOLOGY
Health Canada epidemiological summaries:
INFECTION CONTROL PRECAUTIONS
As SARS is not thought to be an airborne infection, research
must clarify the need for airborne precautions compared with measures
needed to prevent transmission via droplets and contact with body
fluids. The need for protective equipment is related to procedures.
Consideration needs to be given to equipment that provides a good
standard of care and adequate protection while also being affordable
and sustainable. Sophisticated procedures, especially those that
generate aerosols, greatly amplify the risks of infection. [WHO]
In the meantime, until more is known about the exact mechanisms
of acquisition, the Ontario Ministry of Health has provided a
series of directives to Ontario hospitals outlining procedures
that must be put into place in the event of another SARS
outbreak, for high-risk
respiratory procedures (outbreak and non-outbreak conditions),
and isolation precautions for patients suspected of having SARS.
The recommendations for isolation
precautions for SARS patients (suspect or confirmed) include:
- private room, preferably with negative pressure ventilation
and anteroom
- long-sleeved gown
- N95 mask or equivalent, for which the wearer has been fit-tested
- hair cover
- protective eyewear
- full faceshield
- gloves
Equipment should be put on in the above order, and removed in
reverse order. Training and familiarity with these procedures
is an important component of staff protection, as self-contamination
during removal of equipment, with subsequent infection, has been
documented. Refer to the
Ontario directives for complete infection control procedures.
Refer also to
Practical Guidelines for Infection Control in Health Care Facilities
[WHO, Dec. 23/03].
PROTECTING CANADA'S BLOOD SUPPLY
Health Canada issued formal direction to blood operators
on April 10, 2003 as a precaution to protect the blood supply
in Canada and recipients from the possible threat of SARS. Although
there is currently no evidence of transmission of SARS through
blood and blood components, Health Canada has directed blood operators
to temporarily defer from [accepting] blood (for a period of 10
days) from persons who have:
- travelled within the previous 10 days to an affected area outside
Canada. The affected areas are currently: China, including the
Hong Kong Special Administration Region; Hanoi, Vietnam; Singapore
and Taiwan;
- been a patient, worked in, or visited a facility that is under
quarantine for SARS.
LABORATORY TESTING FOR SARS
Antibody tests include ELISA
(IGM/IGA) to detect antibodies in serum from day 20 after onset
of clinical signs. Antibodies have been identified in some patients
as early as 14-21 days after onset. Immunofluorescence
assays detect antibodies in serum after day 10 of onset. Test
is more difficult to perform, requiring live virus in cell culture
and an immunofluorescence microscope, limiting its use to reference
laboratories. PCR can
detect genetic material of coronavirus in various specimens (blood,
stool, respiratory secretions). Several international reference
laboratories have developed primers which are being shared on
the WHO website. Virus from patients with SARS can be grown in
cell culture from respiratory
secretions and blood.
Positive laboratory test results indicate that a patient has
been recently infected with the coronavirus. Negative tests do
not imply that the patient does not have SARS. The sensitivity
and specificity of current tests need to be developed further
before they can be used to confirm a clinical diagnosis. [Ref:
WHO]
For specimen collection from potential SARS patients, refer
to
"Guidelines for Collecting Specimens from Potential SARS
Patients from the CDC and "A
Practical Guide for SARS Laboratories: From Sample Collection
to Shipment" from the World Health Organization.
TRAVEL ADVISORIES [ref: public
Health agency of Canada]
The Public Health Agency of Canada currently has no global
travel restrictions due to SARS.
SARS Links
| Public Health Agency of
Canada |
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| World
Health Organization (WHO) |
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| Centers
for Disease Control and Prevention (CDC) |
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| Provincial
Information |
| Ontario
Alberta
British
Columbia
Manitoba
New Brunswick
Newfoundland
& Labrador
Nova Scotia
Prince Edward Island
Quebec
Saskatchewan
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| Laboratory
Information |
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| Other
Information |
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SARS Publications
-
CCDR 25 March 2003 Epidemiology, Clinical Presentation
and Laboratory Investigation of Severe Acute Respiratory Syndrome
(SARS) in Canada, March 2003
- NEJM
30 March 2003Identification of Severe Acute Respiratory
Syndrome in Canada
- NEJM
7 April 2003 A Major Outbreak of Severe Acute Respiratory
Syndrome in Hong Kong.
- NEJM
10 April 2003Identification of a Novel Coronavirus in Patients
with Severe Acute Respiratory Syndrome
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CCDR 15 April 2003 Preliminary Clinical Description
of Severe Acute Respiratory Syndrome
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CCWR 1 May 2003 The War Against an Unknown Pathogen:
Rising to the SARS Challenge
- JAMA
6 May 2003 Clinical Features and Short-term Outcomes
of 144 Patients With SARS in the Greater Toronto Area
- CMAJ
13 May 2003 SARS: the struggle for containment
- WHO 20
May 2003 Severe acute respiratory syndrome (SARS):
Status of the outbreak and lessons for the immediate future
- CCDR
1 June 2003 Cluster of Severe Acute Respiratory Syndrome
Cases Among Protected Health Care Workers - Toronto, April 2003
- CCDR
15 June 2003 Assessment of In-Flight Transmission
of SARS - Results of Contact Tracing, Canada
- CCDR
1 July 2003 Update - Severe Acute Respiratory Syndrome
- Toronto, 2003
- NEJM
22 April 2004 Evidence of Airborne Transmission of
the Severe Acute Respiratory Syndrome Virus
POST SARS
This section will deal with recommendations and links to expert
resources that offer planning for the future and the "next
season" of SARS, as well as dealing with some of the devastating
effects SARS has had on healthcare in Ontario.
- WHO:
Alert, verification and public health management of SARS in
the post-outbreak period [14 August 2003]. A prescription
for continued vigilance, risk assessment, early notification,
case definitions, laboratory assessment, public health management
and enhanced surveillance.
- Health
Canada: Alert, verification and public health management of
SARS in SARS Situation Update and Continuing National Surveillance
[5 September 2003]. Continued surveillance in previously affected
areas in Canada.
- Amendments
to the Quarantine Act: The Government of Canada has
given notice of its intent to amend the Quarantine
Regulations, in part as a result of SARS
- Directives
to Ontario healthcare facilities in the post-SARS period:
The Ontario Ministry of Health has begun to issue final directives
for ongoing surveillance and control measures for Ontario healthcare
facilities, both in the Greater Toronto Area and outside the
GTA.
- Inadequate
plumbing systems likely contributed to SARS transmission:
Report from the World Health Organization (26 September
2003)
- Health
Canada Report: "Learning From SARS – Renewal of Public
Health in Canada"
- Report
from the Canadian Hospital Epidemiology Committee (CHEC) to
the Nayler Commission: Recommendations for infection
control and hospital epidemiology in the post–SARS period.
- WHO
Concensus Document on the Epidemiology of SARS: Results
of global investigations into the epidemiology of SARS, including
incubation period, infectious period, case–fatality ratios,
exposure dose, risk factors for transmission and individual
geographical SARS experiences.
-
Public Health Guidance for Community–Level Preparedness
and Response to Severe Acute Respiratory Syndrome (SARS):
The US Centers for Disease Control & Prevention (CDC)
has issued a 168–page proposal for containing SARS, and
is inviting medical and public health professionals to comment
on the recommendations. The measures include quarantine provisions
and a new protocol for hospitals dealing with respiratory illnesses.
Quarantine and isolation measures, not used on a large scale
since the first half of the last century, would include "snow
day" measures such as cancelling school and large gatherings,
and perhaps restricting or closing mass transit, among other
things. The plan stresses that quarantine measures would ideally
be voluntary, though there are suggestions for official quarantine
orders if necessary. Draft for public
comment
- Ontario
SARS Commission: Results of the Campbell inquiry
into the SARS outbreak in Ontario (presentations and public
hearings).
- The
Global Search for a SARS Vaccine: While countries
around the world are working to develop a vaccine for SARS,
it will not be available for the 2003-2004 respiratory viral
season.
- The
Walker Panel Report on SARS: Lessons learned in Ontario
from the SARS experience and sweeping recommendations for infection
control, emergency preparedness, public health, communications
and education of health care workers.
-
Ontario Ministry of Health SARS Directives During an Outbreak:
The Ontario Ministry of Health has released final directives
to healthcare facilities in the province for procedures that
are to take place in the event of another SARS outbreak. Directives
include information for transportation of patients, precautions
to be used for cases or suspect cases of SARS, screening tools,
personal protective equipment to be used for high-risk respiratory
procedures and case definitions.
-
Ontario Ministry of Health Report on Recommendations for Infection
Control Standards in Non-outbreak Conditions: The
Ontario Ministry of Health has released final recommendations
for acute care hospitals for infection control standards for
febrile respiratory illness (FRI) under non-outbreak conditions.
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Ontario Ministry of Health Infection Control and Surveillance
Standards for Febrile Respiratory Illness (FRI) in Non-Outbreak
Conditions in Acute Care Hospitals: The Ontario Ministry
of Health has released final standards to acute care hospitals
in the province for respiratory illness surveillance, infection
control practices for patients with febrile respiratory illness,
and regional response levels.
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