“Spock said it best: “Live long and prosper.” I believe that is everyone’s wish. I also believe that our parasites, despite their own selfish behavior, can help us do just that.”—Dickson D. Despommier
In the concluding chapter to People, Parasites, and Plowshares: Learning from Our Body’s Most Terrifying Invaders, Dickson D. Despommier considers a dilemma: our ability to eradicate parasites is at the same time is lessening our understanding of bacterial infections as they evolve. This, compounded with our frequent disregard of nature, is posing new challenges to medicine and science. In the following excerpt, Despommier explores some of these challenges and how perhaps we can confront them:
Despite the life-saving benefits that antibiotic therapies obviously have provided us, we are all too familiar with the plight we now face. Nearly all our commonly occurring bacterial infections, from syphilis and gonorrhea to tuberculosis and hospital-acquired staphylococcus, have taken the next step in their evolution and are now either partially or completely resistant to practically all commercially available antibiotics. If this trend continues, and there is no reason to think that it won’t, soon we will have none at our disposal. But we still desperately need them, since the pathogenic microbes do not seem to have gone away just yet. Today drug development is expensive and time consuming. It takes nearly ten years before any newly discovered antibiotic makes it out of the laboratory and onto the pharmacist’s shelf. The Food and Drug Administration’s stringent set of regulations prohibits the release of any compound before first thoroughly testing it in animals and then ushering it through many expensive, time-consuming human clinical trials. The result is that most large drug companies have folded their tents and declared a truce with the microbes. It has proven too expensive to screen thousands of natural products that are generated randomly from fermentation flasks of exotic soil samples, only to have them flop in some assay or clinical trial. What’s more, after a new drug does reach the market, resistance is an assured consequence of use. Then it is back to the drawing board after an all-too-brief respite from any given infectious disease. Other reasons for drug companies to give up research divisions dedicated to discovering new antibiotic compounds include declining revenues from drug sales owing to competition from generic smaller pharmaceutical companies, and the expiration of “cash cow” patents on older, more widely used antibiotics.
It is obvious to me that nature has all the answers, so what is our question? This is a dominant theme that I have revisited again and again throughout this book. If we are to hold off the pathogens at our doorstep, our question should be: where will our next generation of antimicrobial drugs come from? To answer this I suggest we . first adopt a deeper, more respectful relationship with the natural world. We have to stop plowing over or cutting down entire ecosystems in favor of temporary monetary gains. Mining and farming interests in the rain forests come to mind as an example of such irresponsible behavior. We need time to explore more fully the natural world around us to allow us to identify a wider range of molecules of interest for our own use in fighting off infections. In learning how the rest of life arms itself against their own cadre of pathogens, we will come to realize that there are common grounds that unite us with all other nonparasitic animals and some plants too. Clearly the magainins fall into this general category, along with many other newly discovered molecules with antibiotic activity found in a broad swath of invertebrates (e.g., cecropins from the cecropia moth) and cold-blooded vertebrates (e.g., dermaseptins from the skin of certain species of frog). But despite all this new knowledge, it is hard to predict which family of defense peptides will eventually win the day.
In all natural systems, a balance is eventually achieved between any given host and its pathogens. It has been this way since complex ecosystems have been in existence. The same governing principles also applied to human populations prior to the advent of the antibiotic revolution. Are we going to have to experience that kind of thing each time a new, virulent strain of pathogenic microbe shows up at our door, now that most of these wonder drugs no longer work? Without antibiotics, our only defense, beside the development of vaccines, is an intact immune system, a highly functioning system of public health, and a bit of luck in avoiding exposure to any given infection in the first place.
So, in the end, I am convinced beyond any shadow of doubt that we need to remain on ready alert for the possibility of discovering new compounds from the natural world to feed into our diminishing arsenal of antimicrobials. In summary, I hope that what I have described in these pages will convince even the most skeptical as to the practical value of basic scientific knowledge. That knowing more about the lives of our pathogens, especially those we know little about today, will eventually improve our own lives. Spock said it best: “Live long and prosper.” I believe that is everyone’s wish. I also believe that our parasites, despite their own selfish behavior, can help us do just that.