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Biological Terrorism : Emerging Diseases : Biological Warfare

Environmental Disruption

This becomes clearer when you consider the ecological matrix in which all organisms live. Just like Homo sapiens, pathogenic organisms are integral parts of the environment. They exist in complex and often quite subtle relationships with their vectors and hosts. These relationships have evolved over millions of years and are thus usually quite stable. However when environments change quickly, when ecosystems are transfigured or eliminated, pathogenic organisms are themselves transformed and disrupted. This creates opportunities for microorganisms to jump into new species and into new pathogenic behaviors.

The disruptive pressures can be subtle. For example, when microorganisms are unusually stressed, their mutation rates can increase. This is an evolutionary tactic that allows them to move on to new habitats, should the current habitat become inhospitable. Antibiotics are such a disruptive pressure. In an antibiotic-rich environment, microorganisms naturally mutate into forms that can resist the antibiotic. Over time this means that diseases that once were curable become effectively incurable. This can be seen today in diseases as far-ranging as Tuberculosis and Malaria.

Global warming is another example of pervasive environmental disruption. The links below note a wide range of effects on disparate areas of our planet, such as the extinction of native birds in Hawaii and dying of oyster fields in Maine. While seemingly isolated events, all are connected to the increasing spread of novel pathogens due to environmental disruption, specifically global-warming.

However, it's fair to say that not all scientists are convinced that global warming will necessarily lead to an increase in all diseases. For example, malaria mosquitoes require both warm and wet weather, and some climatic models predict future drier conditions for the warming temperate zones. Thus, increases in malaria may be more isolated and sporadic than simple models might suggest.

However, in aggregate the best scientific information now is that global warming will lead, on average, to a much-higher disease burden for Homo sapiens as well as other species. This is due to the fact that systematic planetary warming will necessarily have systematic effects on all parts of the globe. History and experimental data show that such disruptions invariably lead to rapid adaptation and radiation of microorganisms and their vectors. This combined with the rapidly growing world population and increased urbanization, means that mankind will inevitably be hit with a wider variety of more-virulent diseases.

Other disruptive pressures include air and water pollution, deforestation, and rapidly-expanding human populations. These all alter the natural balance, leading to an increased possibility of epidemic or pandemic disease. River Blindness (resulting from bad irrigation practices increasing the spread of the snail host), is one of many examples of this dynamic.

The extinction or severe depletion of species is another form of disruption. When the host for a pathogen is increasingly rare and stressed, or in increasing contact with expanding human populations, then a jump to Homo sapiens becomes an increased possibility. HIV, which jumped from diminished Chimpanzee populations to swelling human populations, is an example.

This is a general phenomenon. Pathogens which are widely present in undisturbed forests usually do not constitute a threat, given that man is not a natural host. However, if the preferred non-human host is removed then that creates a selection pressure for the pathogen to jump to another host. The total elimination of an ecosystem, such as a forest, is one way to eliminate a wide range of natural hosts, thus forcing pathogenic organisms into the human ecology. This particular dynamic is most vivid in the African rainforests and in the Amazon, where large scale ecological disturbances are literally shaking ancient viruses out of the trees and into local human populations. From there it is a short airplane ride to all the urban centers of the world.

Link: Global Disease
Link: Study on global warming and disease
Link: Climate change linked to disease
Link: NYC Encephalitis and Global Warming
Link: Extinction And Health
Link: Environmental Stresses Emerging Disease and Crashing Amphibian Populations
Link: Water Pollution And Infectious Disease
Link: Global warming disease warning
Link: Global Warming and Disease
Link: Fewer Trees, More Disease