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evere acute respiratory syndrome, or
SARS, is a contagious and potentially fatal respiratory illness.
It first
appeared in China in November 2002 and was identified in February 2003.
SARS spread
to over 24 countries before it was contained. Since May 2004, no new cases have been reported.
From
November 2002 to July 2003, there were 8,098 cases worldwide
and 774 deaths.
The United
States (U.S.) saw eight laboratory-confirmed cases and no fatalities. All eight
people had traveled to areas affected by SARS.
Strong
levels of global cooperation ensured that the threat of SARS was dealt with
swiftly, and the spread of the disease was effectively contained.
What is SARS?
The SARS coronavirus (SARS-CoV) causes SARS. A coronavirus is a
common form of virus that typically causes upper-respiratory tract illnesses.
The common cold results from a kind of coronavirus.
Six
different kinds of coronavirus are known to infect humans. Four of these are
common, and most people will experience at least one of them at some time in
their life.
The two
other types cause SARS and Middle East Respiratory Syndrome (MERS). These are less common but far more deadly.
Before SARS
appeared, coronaviruses had not been particularly dangerous to humans, but they
had been known to cause severe diseases in animals.
As a
result, scientists first thought that animals transmitted SARS-CoV to humans.
They now believe that an animal virus changed into a new, more deadly strain.
Causes
Droplets
from coughing and sneezing and close human contact likely transmit the SARS
virus. The respiratory droplets are probably absorbed into the body through the
mucous membranes of the mouth, nose, and eyes.
This could
be through:
- hugging
and kissing
- sharing
utensils for eating and drinking
- speaking
to someone within a distance of 3 feet
- touching
someone directly
A person
with the virus can spread the infection by leaving respiratory droplets on
objects, such as door handles, doorbells, and telephones. These are then picked
up by someone else.
The virus
is likely to remain active in the environment for several days.
Why
do we worry about zoonotic diseases?
Diseases
that pass from animals to humans are called zoonotic diseases. They are
relatively rare.
The main
concern when they first emerge is that they are new strains and also new to
humans, so the human body does not yet have immunity.
It is often
impossible to predict what may happen. In the case of SARS, animals may have
been a host for the virus.
In 2013,
scientists discovered that
two new coronaviruses found in Chinese horseshoe bats are a close relative of
the SARS-coronavirus.
A report
published in 2014 suggested that over 320,000 mammal
viruses have not yet been discovered.
Symptoms
Symptoms
normally appear within 3 to 5 days after exposure to the SARS virus, but they
can develop after 2 to 7 days. During the incubation period, before symptoms
appear, the disease is not contagious.
Most cases of SARS begin with a high fever.
Other early symptoms include those common to flu, such as aches, chills,
diarrhea, dry coughing, and shortness of breath. These will develop over the
course of a week.
Patients
may go on to develop pneumonia, an infection of the lungs.
Serious
complications, such as respiratory failure, heart failure, and liver failure may occur.
These
complications are more likely in people aged over 60 years, and those with
pre-existing co-morbidities, such as diabetes or hepatitis.
Diagnosis
The World
Health Organization (WHO) advises that,
to be diagnosed with SARS, a person must have all of the following:
- a fever of at least 100.4° Fahrenheit or 38° Celsius
- one
or more symptoms of lower respiratory tract illness: a cough, difficulty
breathing, shortness of breath
- radiographic
evidence to suggest a diagnosis of pneumonia
- no
alternative diagnosis to fully explain the illness
SARS is
very rare, and the symptoms overlap with those of flu and pneumonia. A physician will not suspect it unless
the person has been in an area where there is an outbreak.
Tests
Laboratory
tests can help identify SARS-CoV.
Reverse transcription-polymerase chain
reaction (RT-PCR) testing
can detect the virus in blood, stool, and nasal secretions.
Serologic testing can detect SARS-CoV
antibodies in the blood. If a person has antibodies, they are also likely to
have the infection.
Doctors may
also use a viral culture.
This involves putting a small same of body tissue or fluid into a container
with some cells in which the virus can grow. If the virus grows, the cells will
change.
These tests may not be reliable if
used in the early stages of infection.
Most of the
patients who developed SARS in 2003 to 2004 had spent time with people who
developed the disease, or they had been in places where the disease was
present.
Pneumonia
is a common complication, so a person who develops unexplained pneumonia and
has a spent time in a place where there is an outbreak should be suspected of
having SARS.
This can
include living in or recent travel to an area affected by SARS or working in a
laboratory that contains live SARS-CoV.
Treatment and
prevention
The U.S. did not require people
with SARS to enter quarantine during the 2003 outbreak, but SARS is a
reportable disease. It is also a medical emergency, and urgent medical care is
needed.
The WHO recommends isolating
patients and using barrier techniques to prevent the spread of the virus,
including filter masks and goggles. No drug, including antibiotics, appears to be effective against SARS.
Supportive
care is recommended, including the use of medications to relieve symptoms such
as fever and a cough.
Prevention
As with
other infectious diseases, some simple steps can be taken to help prevent the
SARS virus from spreading.
Good
personal hygiene practices can help restrict the spread of the virus.
These
include:
- frequent
handwashing
- avoiding
touching the eyes, mouth or nose with unclean hands
- covering
the mouth and nose with a tissue when coughing or sneezing
- encouraging
others to do the same
Because
SARS is contagious once its symptoms have developed, anyone with the disease
should limit their interactions with other people until 10 days after their
symptoms have improved. SARS is at its most contagious during the second week
of illness.
Is
there a vaccine?
There is
currently no vaccine against SARS, but scientists are working on one.
In 2013,
researchers announced that
they had found a way to disable a part of the virus involved in SARS that
allows it to hide from the immune system. This could lead to the development of
a vaccine against the disease.
Since 2004,
there have been no recorded cases of SARS anywhere in the world. Health
organizations continue to work on a response, in case SARS reappears in the
future.
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