by Gwynne Dyer

The virus that causes Severe Acute Respiratory Syndrome (SARS) was identified on April 15 in a ten-country collaboration between 13 laboratories as a corona virus related to those that cause the common cold.

"Now we can move away from methods like isolation and quarantine and move aggressively towards modern intervention strategies including specific treatments and eventually vaccination," said David Heymann, executive director of the World Health Organisation's communicable diseases programmes.

That's the optimistic view. In Canada, where most of the SARS cases outside Asia have occurred, the tone is more cautious. "The problem in China is out of control so this is a virus that's not going away. We've got this forever," said Dr Donald Low, chief microbiologist at Toronto's Mount Sinai Hospital. But if quarantine measures continued to restrict the disease's spread, he hoped, there would be time to develop a vaccine, or at least better therapeutic measures and diagnostic tests, before it spread too widely.

Almost on the same day, however, news broke that around five hundred members of a religious group in Toronto had been exposed to SARS and had continued to move around the city in the course of their normal lives for a week afterwards, raising the risk that the city is about to tip over into "community spread". That happens when the diffusion has become so wide, and the difficulty of tracing all the contacts of each infected person so great, that individual quarantine ceases to be effective and it may be necessary to consider quarantining the whole community.

The worst of the four scenarios developed by scientists advising the SARS team in Toronto and leaked last week to the Globe and Mail envisaged an epidemic spread of SARS in the city in which "the health-care system would be overwhelmed. Case fatality rates could rise due to inability to provide optimal care. Considerable societal disruption could occur and maintaining even essential services could become problematic."

That is the extreme case, of course, but it is not inconceivable.

The SARS virus is actually deadlier than the "Spanish influenza" virus that caused the great pandemic of 1918, which infected between 20 and 40 per cent of the world's population and killed 20 million people in four months. SARS kills four per cent of its victims compared to 2.5 per cent for the Spanish flu. The difference is in the speed with which it spreads: when the Spanish flu struck with full force in the autumn of 1918, tens of thousands died in just the first few weeks—and the young and healthy died just as fast as the old and those suffering from chronic health problems.

SARS, on the other hand, has probably killed fewer than 200 people in three months, and most of the victims have been over 65. The only worrisome thing is that the Spanish flu began with a mild version that travelled around the world in the spring of 1918, and then came back a few months later in a far more virulent form to ravage the planet—at which point public health care did collapse in many places and families had to look after their own as best they could. "I don't think we know where on the path we are (with SARS)," said Dr Edwin Kilbourne, professor emeritus at New York Medical College and one of the world's leading experts on the 1918 pandemic.

The speed with which the medical world can identify new diseases and generate new vaccines is far greater than in 1918, but so is the speed with which new diseases can travel around the globe, thanks to cheap air travel. Since the main way for viruses to mutate into new and lethal strains is by hopping back and forth between people and their domestic animals, the urgent lesson to be learned from this episode is that China must clean up its act.

South China, where many rural people live under the same roof as their animals but also travel widely in the world, is a leading source of new viruses. The SARS virus first appeared there, in Guangdong province, in mid-November, but the Chinese government suppressed the news. It only came to the world's notice when Dr Stephen Cunnion, president of International Consultants in Health Inc, of Silver Springs, Maryland, which is currently installing modern labs in China, posted a query about the rumoured epidemic in Guangdong on an infectious diseases website in mid-February. By then, 305 people had been infected and five had already died.

"If (Beijing) would have acknowledged this early, and we could have seen the virus as it occurred in south China, we probably could have isolated it before it got out of hand," said Dr Cunnion. "But they completely hid it. They hide everything. You can't even find out how many people die from earthquakes."

The cover-up continues even down to the present: Alan Schnur, head of WHO's office in Beijing, visited military hospitals in Beijing this week after Jiang Yangyon, a former surgeon at one of the hospitals, accused Health Minister Zhang Wenkang of systematically understating the number of those infected in China. Schnur concluded that Beijing probably has "between 100 and 200" cases of SARS, not the 37 officially declared.

This has got to stop. No considerations of Chinese pride or special political circumstances can excuse this kind of behaviour, which exposes the whole world to risk. Pressure should be brought on the Chinese government to guarantee that next time, everybody in the world hears about a new disease at the same time. How much pressure? As much as necessary.