More columns By David Suzuki

SARS, BSE and West Nile aren\'t just making headlines, they\'re making history. These diseases are truly products of our age - an age of global transport, industrialized agriculture and global warming. And they represent the tip of the iceberg in terms of emerging diseases.

Humans today are pushing every conceivable ecological boundary. We are displacing animal habitats, feeding meat products to herbivores, dining on exotic predators and doing it all while rushing madly about the planet in cars, boats and jet airplanes. We are everywhere and meddling in everything. As a result, we are being exposed to \"new\" diseases that have never before infected humans.

Look at SARS. It now appears this latest disease epidemic may have originated in civet cats - a small, wild, nocturnal mammal that happens to be considered a delicacy in southern China. Humans may have become infected when these animals were slaughtered for food.

That sounds disconcertingly familiar to another global disease epidemic that has now killed nearly 20 million people worldwide - AIDS. HIV, the virus believed to cause AIDS is thought to have been spread to humans from chimpanzees through the bushmeat trade. AIDS has taken a tremendous toll in Africa. In the next 17 years, some 55 million Africans are expected to die from the disease.

And there\'s more. Earlier this spring, a Dutch veterinarian became the first human to succumb to the Highly Pathogenic Avian Influenza that has been ravaging poultry farms in the Netherlands. About 100 other people also contracted the disease, which forced authorities there to slaughter more than 18 million chickens. The disease has also spread to pigs, which are ideal virus incubators and can act as intermediaries for a virus to spread from other animals to humans.

Four years ago that happened when Malaysian pig farmers hacked into forests to make room for their farms. Fruit bats that used to live in the forests began to roost in barns and building rafters. Their droppings, which carried a virus called Nipah, contaminated the pigs\' feed. Although the virus appears to be harmless to bats, it causes a brutal cough and often death in pigs. From the infected pigs, the virus soon spread to farm workers, who developed similar symptoms. More than 100 people died and authorities had to slaughter more than a million pigs.

Closer to home, West Nile virus, which is spread by mosquitoes, killed 284 people in the United States last year and infected thousands more. West Nile only appeared in the U.S. in 1999, and has since spread to most states and Canadian provinces. Some experts say that global warming may have been a factor in the spread of West Nile, as recent droughts have encouraged the proliferation of the type of disease-carrying mosquito that prefers shallow, organically rich pools of water.

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Hantavirus, Ebola and Hendra are just a few other new diseases to recently emerge in humans. In fact, in the past 30 years, more than 35 new infectious diseases have been diagnosed. Deaths from infectious disease in the U.S. are now double what they were in 1980. And three quarters of all these emerging diseases have jumped from animals to humans.

Experts say that we are entering a new age of infectious disease and it\'s largely due to human activities. When we push deep into forests and jungles, we expose ourselves to new diseases. When we practice intensive livestock farming and feed herbivores to herbivores, we create ideal conditions for the spread of disease. As we change the climate, we create new vectors for disease to spread. The growth of international trade and travel further increases the capacity for diseases to flourish.

Some of these factors we cannot change. But some we can. We can work to end the bushmeat trade in Africa and Asia. We can curtail the continued destruction of our forests. We can enforce better livestock practices. We can reduce the fossil fuel emissions that are causing global warming. Indeed, these are steps we must take if we want a healthier future.