"What threads we silently break; what voices we still. By what grace, I wondered, have we been kept so well by what we have abused for so long." (p. 95)
This expression by science writer and journalism professor Mark Jerome Walters was inspired by a walk in an old growth forest, and is in reference to the planet's ecology. It is indicative of his reflective and eloquent style.
It was thought not so many years ago that we had infectious diseases nearly under control and it would be only a matter of (short) time before they were eliminated as important causes of human morbidity. How naive such a pronouncement seems today!
The six modern "plagues" that Walters writes about are mad cow disease, HIV/AIDS, antibiotic-resistant salmonella, Lyme disease, the four-corners hantavirus, and West Nile virus. There is an Epilogue in which he discusses SARS and mentions avian flu, which is making headline news today as I write this. Walters's argument in each of these cases is that these diseases have come to prominence because of something we humans have done.
In the case of mad cow disease we have been mixing remnants from slaughtered cows and sheep in with their feed, including brain and nervous tissue parts that contain the prions responsible for the disease.
In the case of HIV/AIDS we have been clearing forests in the African jungles, and to feed the loggers have increased the traffic in bushmeat resulting in a commingling of humans and wild simians providing an opportunity for the virus to jump from apes to people.
In the case of Salmonella typhimurium DT104, it is our feeding antibiotics to farm animals that has allowed the antibiotic-resistant strain to develop.
Lyme disease, Walters argues is the result of our encroachment on forests that have been depleted of their natural variety of species with the result that the mice and deer that harbor the ticks that are the vectors for Lyme disease appear in unnaturally disproportionate numbers especially following seasons of acorn abundance.
A similar overabundance of mice in the Southwestern part of the US following El Nino years of heavy rains leads to more mice eating more pine nuts resulting in more human deaths from the hantavirus carried by the mice.
In the case of West Nile virus, it is the international traffic in birds that has allowed the virus, native to the Nile River in Egypt to get on planes and come to the US and other places in the world where indigenous mosquitos bite the birds and then bite native species and humans. Or, it is the mosquitos themselves who catch the planes and travel anywhere in the world, their cache of virus stowed inside their bodies.
Walters writes eloquently of these diseases and the tragedies they are causing. His purpose is to increase public knowledge about what we are doing to the environment and how that disturbance is wrecking havoc with the long establish ecosystems, and--like a tornado among forest litter--is causing pathogens that normally would not come into contact with humans, to literally fly into the air and be presented at our doorsteps.
Walters does not include drug-resistant tuberculosis (although he mentions it), which is even more of a threat to human health than some of the diseases above, but if he had, the story would have been similar. In a world in which a person or a pathogen can get on a plane and be just about anywhere else in the world in a matter of hours is a world in which infectious disease can spread and trade genetic material as if by design. We are the designers of this morbid mix, nurturing exponentially increased chances for pathogens to mutate into ever more deadly strains while foolishly wasting our antibiotics in support of profit margins for poultry and meat conglomerates.
Walters recalls the first waves of epidemic disease that visited humankind beginning with the agricultural revolution some 10,000 years ago, and then how the trade between the new civilizations ushered in a new wave of epidemics about 2,500 years ago, followed by the horrific spread of disease during the age of exploration following the Columbian voyages. He now sees us "entering a fourth phase of epidemics, spawned by an unprecedented scale of ecological and social change." (p. 9)
Because Walters writes so well, and because he is such a passionate spokesperson for the fact that we are part of the planet's ecology and not above its logic, and because the next "ecodemic" is just around the corner, this is an important book that deserves a large readership. Sooner or later, a new strain of a virus or other pathogen is going to attack humans with a virulence to equal or exceed that of any plague of the past. We may have no defense until the disease has run its course, and so it is prevention that we must depend on.
Bottom line: eloquently-written and as timely as the evening news.