—from Epidemiological Bulletin,
Vol. 24 No. 2, June 2003—
Severe Acute Respiratory Syndrome (SARS) Update
Since 28 May 2003, the SARS epidemic has been on a decline. In
fact, at the time of this publication, the last reported probable case in the
world was detected and isolated on 15 June 2003 and it has been more than 20
days, or twice the incubation period, since the detection of the last case.
The chain of human-to-human transmission is therefore considered to be broken,
which means that the SARS coronavirus is no longer thought to be circulating
in the human population. WHO continues to receive rumors of possible cases,
which indicates that surveillance systems are working well. To date, all recently
reported probable cases have been investigated extensively and determined to
have other causes.
However, scientists cannot at present guarantee that SARS has
been eliminated, as questions remain about the origins of the virus and its
possible seasonal occurrence. In addition, transmission may be occurring somewhere
in the world at such a low level as to defy detection.
The world population must be considered vulnerable to a return
of SARS pending better understanding of the origins of the virus and the circumstances
that might have allowed it to jump from an animal host or environmental source
to infect humans. Without such an understanding, predictions of the future evolution
of the outbreak – including its end – cannot be made with certainty.
Since the start of the SARS global epidemic in March 2003 until
July 9, there have been a total of 8,436 probable cases and 812 deaths worldwide
in 29 countries. Most of the cases occurred in health care workers and close
contacts to patients. In the Americas, SARS has directly affected Canada and
the United States the most. Brazil reported 3 probable cases (2 of them were
later discarded) and Colombia 1 probable case.
WHO is moving from an emergency response to a research-based agenda
aimed at protecting the world against any future resurgence of SARS. Far too
little is understood about the origins of the SARS virus and the possible role
– if any – that animals play in the transmission cycle. In addition,
an adequate point-of-care diagnostic test is still not available for SARS. The
laboratory tests would likewise need to be sufficiently simple and affordable
to be used in countries with different health systems and resources for health
care. These issues are expected to top the research agenda on this disease.
In the meantime, WHO has good reason to believe that, should SARS
resurface later this year, the global impact will be milder than experienced
during the initial global emergency. Five reasons support this view.
First, the world’s public health systems have demonstrated
their capacity to move quickly into a phase of high alert. The prompt detection
and isolation of imported cases in Latin America, Africa and India are good
examples of both the level of vigilance and its effectiveness in preventing
further spread. Some of the former SARS hotspots, including Hong Kong and Singapore,
plan to maintain a high level of vigilance, supported by measures for screening
and detection, until at least the end of the year.
Second, the world knows what to do. Control measures have
demonstrated their capacity to completely halt outbreaks. In the Americas, countries
have mobilized national resources to review and adapt international surveillance,
prevention and control guidelines to face the potential introduction of the
disease and investigate possible cases.
Third, the intensive research effort currently underway
can be expected to improve scientific understanding of SARS and yield better
diagnostic and control tools.
Fourth, resolutions adopted during the May World Health Assembly have strengthened
WHO’s capacity to respond to outbreaks, allowing it to move from a passive
reliance on official government notifications to a proactive role in warning
the world as soon as evidence indicates that an outbreak poses a threat to international
public health.
Finally and perhaps most importantly, SARS has underscored
the importance of immediately and fully disclosing cases of any disease with
the potential for international spread. In the present climate of opinion, influenced
by the lessons learned from SARS, it appears unlikely that any country would
choose to conceal cases, should SARS resurface. Countries are being urged to
use their experience with SARS to strengthen epidemiological and laboratory
capacity as part of preparedness plans for responding to the next emerging infection
or the next influenza pandemic.
As SARS has clearly demonstrated, the appearance of a new disease
in a highly mobile, interconnected and interdependent world can have serious
repercussions outside the health sector and far beyond the areas worst hit by
the outbreak. This sense of shared vulnerability is considered a strong motivation
to continued international collaboration for the prevention and control of priority
diseases.
References:
(1) World Health Organization. Update 89 – What happens if SARS returns?
Situation Updates – SARS [Internet page]. Available at: http://www.who.int/csr/sars/archive/en/.
Accessed on 11 July 2003.
(2) World Health Organization. Update 91 – SARS research: the effect of
patents and patent applications. Situation Updates – SARS [Internet page].
Available at: http://www.who.int/csr/sars/archive/en/.
Accessed on 11 July 2003.
(3) World Health Organization. Update 96 – Taiwan, China: SARS transmission
interrupted in last outbreak area. Situation Updates – SRAS [Internet page].
Available at: http://www.who.int/csr/sars/archive/en/.
Accessed on 11 July 2003.
Source: Prepared by PAHO’s Area of Disease Prevention and Control,
Communicable Diseases Unit (DPC/CD).
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Epidemiological Bulletin, Vol. 24 No. 2, June
2003
