SARS is the first new public health epidemic of the 21st century and the public health community's first opportunity to mount a coordinated, early response.

We are dealing with a new disease striking a globalised society. We have seen its rapid international spread. We have seen stock markets rise or fall in response to the latest success or setback in the SARS situation. We have seen the disease on the front pages and on television. We have seen the closure of hospitals, schools, and borders and witnessed economic fallout, population movements from affected cities, and unwarranted discrimination.

But we have also seen unprecedented international solidarity against this shared microbial threat of unknown dimensions. And we have seen SARS stopped dead in its tracks in some of the wors affected areas.

SARS has changed the perception of the infectious disease threat. It has also raised public health to a new level of importance.

High price

The first and most compelling lesson we must learn from SARS concerns the need to report, promptly and openly, cases of any disease with the potential for international spread. In a globalised, electronically-interconnected world, attempts to conceal cases of an infectious disease for fear of social and economic consequences must now be recognised as carrying a very high price. This includes the loss of credibility in the eyes of the international community, and its negative economic impact, damage to the health and economies of neighbouring countries, and a very real risk that outbreaks within the country's own territory can spiral out of control.

SARS also shows the decisive role of political commitment at the highest level. Vietnam, which became the first country to break the chain of transmission in late April, showed how a developing

country, hit by an especially severe outbreak, can triumph over a disease when reporting is prompt and open and when World Health Organisation (WHO) assistance is quickly requested and fully supported.

This success, subsequently repeated in Singapore, Hong Kong, the China mainland and very likely soon in Taiwan and Canada shows that SARS can be contained despite the absence of robust diagnostic tests, a vaccine, or any specific treatment. When awareness, commitment, and determination are high, even such traditional control tools as isolation, contact tracing, and quarantine can be sufficiently powerful to break the chain of transmission.

The urgency of SARS challenged the WHO to set in motion high-level scientific and medical collaboration.

Within a week of the first global alert, the WHO had established three "virtual" SARS-dedicated networks of virologists, clinicians, and epidemiologists to ensure a continuous research effort equal to the magnitude of the SARS emergency.

One month after, eleven leading laboratories had joined the WHO collaborative effort, and participating scientists collectively announced conclusive identification of the SARS virus. Complete sequencing of its RNA (ribonucleic acid, a chemical essential to protein synthesis in cells) followed shortly. This success is an encouraging sign of the willingness of the scientific community to collaborate, rather than compete, in solving the mysteries of a threat shared by all of humanity.

Expose weaknesses

On the negative side, SARS has exposed serious weaknesses in health systems around the world. The disease places an enormous burden on health services in terms of infection control, isolation,

long periods of intensive care, and the demands of contact tracing and follow-up or quarantine. Even in areas with highly-developed social services, the burden of coping with SARS and the number of hospital patients and health workers who became infected often brought health systems to the verge of collapse.

SARS will not be the last new disease to take advantage of conditions in a globalised world. In the past two decades, new diseases have emerged at the unprecedented rate of one per year,

and this trend is likely to continue. Improved surveillance and reporting systems, mechanisms for collaborative research,hospital policies, procedures for infection control, and channels for informing and educating the public are part of the positive legacy of SARS.

The reality is that public health is, as never before, a priority on the global agenda for the simple reason that so many of the challenges we now face have a global impact and thus require global solutions and a global response. Our task is to build trust and solidarity.

In an interconnected and interdependent world, bacteria and viruses travel almost as fast as email messages. There are no health sanctuaries, no impregnable walls between the world that is

healthy, well-fed, and well-off, and another world which is sick, malnourished and impoverished. Globalisation has shrunk distances, broken down old barriers, and linked people together. It has also made problems halfway around the world everyone's problem. The tenacity of the SARS virus and the public health and economic uncertainty it brings underscore this all too well.

Surveillance and effective response are an important expression of solidarity in public health. They save lives, protect economies, and are an essential pillar of both national and international security. If the world can unite against SARS, we should be able to address other health scourges, especially those which affect not thousands but millions of people. - IPS

Gro Harlem Brundtland is Director-General of the World Health Organisation and former Prime Minister of Norway.