Last week, doctors proudly announced they had identified the killer virus that causes SARS. But deep inside their labs, other scientists are less sanguine. Quietly holding their breath, they are posing a most frightening question: What's next? "SARS is an indication of what we can expect in the future," says Stephen Morse, an expert on emerging infectious diseases who teaches at Columbia University. "The conditions that allow pathogens to reach large populations and spread globally have increased in recent years and will continue to grow."
It's not as if viruses have suddenly got more muscular in the past few years. But the earth's changing environment has meant a proliferation of new bugs that can zip across the world faster than ever before. Rapid deforestation has brought humans into contact with viruses that had been secluded for centuries. Then, a plane ride can bring a strange pathogen from the deep rain forest to an international metropolis in just a day. Modern intensive farming methods, which cluster many animals together, also exacerbate the problem by allowing new diseases to spread like wildfire. Pigs are particularly dangerous, because they can be infected by human viruses and those from animals such as rodents and fowl, making them the most potent mixing vessels in which pathogens can mutate and jump from animal species to humans.
It's no surprise, then, that southern China is thought to have been ground zero for the deadly SARS virus. For centuries, Guangdong province has had the world's largest concentration of humans, pigs and fowl living in close proximity, explaining why many influenza outbreaks can be traced back to that region. But with the intensive farming technique of concentrating livestock increasing worldwide, many more viral breeding grounds are being created. "Italy, for example, has the potential and has been cited by some scientific studies," says Morse, "but there are other places that replicate the same conditions."
Despite such sobering trends, there is some reassuring news. Plague scenarios may be common in Hollywood films, but it is highly unlikely that the current SARS virus will change into something more infectious or deadly—at least in the short term. "Such changes take time," says Malaysian microbiologist Lam Sai Kit, who led the team that isolated the 1997 Nipah virus responsible for 105 deaths in Malaysia and the culling of more than 1 million pigs there. "Take the case of influenza A virus. The last major change was in 1969, and up until now there has not been another major antigenic shift."
Moreover, the coordinated efforts against SARS by scores of scientists show that global teamwork is effective. In just three weeks, scientists have zeroed in on the virus believed to cause the deadly pneumonia; before such cooperative systems were in place, says Lam, it could have taken months. Nevertheless, the SARS outbreak underlines the importance for early warning, given the threats that such rapidly transmitted new diseases pose. "This disease could spread to more countries if information isn't made available," says Lam. In fact, "if we had information about SARS in China last year, it might just have been possible to confine it there."
