Everyone with a TV or access to radio, the Internet, or other humans is aware of the global threats posed by environmental degradation–it’s getting hotter, water levels are rising, and innumerable species continue to be lost to history as a result of environmental changes. But one less-discussed horror resulting from human encroachment on the natural world may frighten even those who poo-poo the gravity of our environmental negligence–and that something is disease. Global research initiatives combining the efforts of zoologists, ecologists and epidemiologists point to a very strong connection between the increased human footprint on the natural world and the increasing prevalence of many major diseases over the last fifty years, and in particular, the last decade or so. In fact, 60 percent of emerging infectious diseases that affect humans are zoonotic–originating in animals–and more than two-thirds of these originate in wildlife. Zoonotic diseases are nothing new–take the Bubonic plague or malaria for example–but the growing human population and a concurrent rise in deforestation, wildlife trafficking and humans living on what was once wild territory has meant increased contact with animals and ecosystems with which, from a pathological standpoint, we are ill-equipped to cope. Nor is it a problem of the “third-world” alone. AIDS, for example, transferred from the chimpanzee population to humans during the 1920’s when hunters in Africa killed and butchered them. Thus far, the epidemic has claimed 28 million lives worldwide. And more recently, the H1N1 and West Nile viruses (both caused by human interaction with animals) have claimed lives in the United States and elsewhere. Indeed, more than two million people are killed every year by diseases that spread to humans from wild and domestic animals, according to a study recently released by the International Livestock Research Institute.
With modern air travel and global trade connections, the possibility for what would once have been a local outbreak to become global epidemic is increasingly great. And the World Bank estimates that another severe influenza pandemic at this point could cost the world economy some $3 trillion. But is the cataclysmic epidemic not a relic of the medieval imagination? Do they still occur? And just how destructive can these illnesses be? Well, the H1N1 virus that began in Mexico and spread across the world in 2009 killed an estimated 1 million people–but that is a relatively light casualty count. The Spanish Flu pandemic that struck the world in 1918 took more than 500 million lives. By comparison, World War I’s four years of gruesome conflict–which ended that same year–took only 17 million.