Emerging Infectious Diseases: Philosophical And Theological Implications

Emerging infectious diseases are infections that have either newly appeared in a population or that have existed but are rapidly increasing in incidence or geographic range. But what makes these emerging infectious diseases special and sets them apart from disease in general? Are emerging infectious diseases indicative of underlying causes and dynamics or are they independent of any greater interpretation? Certainly, disease is nothing new to the human experience and has been a part of our existence from the beginning. The earliest recorded histories comment on illness. Not until relatively recently in human history, however, have we been able to distinguish between infectious and non-infectious diseases.

As we approach the 21st century and a new millennium, it is perhaps a good time to take stock of our existence and our world, to examine where it is we have come from and survey, albeit incompletely, where we are going. Traditionally, humans have regarded themselves the masters of the universe, the center of all existence, created in the image of God as the culmination of all God's creation. Human beings have perceived themselves as representing the pinnacle of corporeal existence. Many religions teach that humans have been endowed by God to create meaning and bestow meaning upon life, though in many religious traditions we have been explicitly instructed by the Creator of the universe that we are not gods ourselves. We are sentient and to some degree prescient, but not omnipotent and omniscient. We are, it turns out, at least presently constricted by the forces of space and time. We are fallible and shortsighted, subject to petty whims and desires, full of avarice and greed but also capable of greatness, of love and honor, respect and duty. We are capable of retrospection, introspection and prediction. We possess the ability to think analytically. And we have the tendency to overestimate our abilities and drift into grandiosity.

Ever since Gallileo put a dent in the theological view that humans, and earth, were at the center of the universe, humankind has witnessed a gradual philosophical decline of prominence in the hierarchy of creation. We have witnessed the birth of many new philosophies, of angst and nihilism and post-modernism, and the response of theologies to grapple with newfound philosophical understandings and interpretations of the life experience. And much of this thought centers around the human condition of suffering. The question that is asked takes on many forms: where is God or where is love or where is grace? And the answers are not always emotionally satisfying: religion relies on faith, philosophy on reason and most of humankind on the stubborn will to survive.

It is against this oversimplified backdrop that we must place the relatively new understanding of the phenomena of emerging infectious diseases. It is true that they threaten our physical survival, but even more fundamentally they threaten our own perception of our place in the hierarchy of existence. Within the last 50 years our understanding of the biological basis of life has undergone tremendous transformation. DNA, RNA and the genetic code have been unlocked. We have discovered the existence of retroviruses and antibiotic-resistant bacteria. We have witnessed the summary execution of innocent human beings by the above-mentioned principles and we have been forced to face the realization that microbes don't fundamentally care about the existence of human beings. Even more, in the realm of evolutionary biological life, we are inconsequential: no more, and no less, special than a bug or a squirrel or a tree. Human beings have intellectually separated themselves from most of the rest of the biological world on the basis of mental constructs such as sentience. But on a purely physical level, the great struggle for survival does not distinguish between any life form, be it human, animal, plant or microbe. A microbe certainly does not discern between living forms. Further, there is no guarantee that any life form will survive to the end stages of the planet's capacity to support life.

In the 1940s, 50s and 60s, there was great optimism in the medical and scientific community regarding our ability to eradicate disease. Antibiotics were being discovered and the miracle drugs were producing results beyond anyone's wildest dreams. The polio vaccine was created and suddenly it appeared that there was nothing we could not do to improve the health and well being of humankind. It surely was only a matter of time before we had in hand the cure for the majority of the diseases inflicting the world's human population. This was, of course, before we new much about the molecular mechanisms of disease and the disease-causing microbes, before the concept of microbial ecology and directed mutations. We were truly becoming the rightful guardians and masters of our world, the caretakers of creation. Experts from around the world were saying that it was only a matter of time before infectious diseases were essentially eradicated and we should begin investing our time and money in curing the chronic diseases. Time has proven these expectations unrealistic. Infectious diseases remain the leading cause of death worldwide even though there have been decreases in certain infectious diseases.

The occurrence of emerging diseases is not new, though the incidence appears to be rising. In the Middle Ages the bubonic/pneumonic plague brought terror and substantial suffering to the populations of Europe in the middle of the 1300s, where an estimated one-third of the population died, and again in the middle of the 1600s. Although leprosy died out with the dissolution of the plague, tuberculosis swept in on the heels of the exiting plague and was exacerbated by the living conditions in urbanized medieval centers. Cholera also caused much hardship in the urban centers through the contamination of water supplies. As a general rule, urbanization enhanced and accentuated infectious diseases, though this was not understood in the middle ages. Urbanization provided a greater congregation of human beings, which in turn provided a more fertile ground for the germination and maturation of infectious diseases and full-blown epidemics. It also allowed for the steady propagation of pandemics and endemics which, in their own right, contributed to the development of epidemics. It is interesting to note that many urban diseases declined in cities in the Northern hemisphere when social reform campaigns emerged which were responsible for improving basic urban living conditions.

One could certainly point out as many factors contributing to the perpetual existence of infectious diseases as there are humans, but key factors are human behavior and the conditions in which people live and work. With increasing urbanization, people began living closer and closer together. Anonymity also comes, paradoxically, in large groups, so behavior was not as dictated by social norms as it was in more rural settings. This resulted in an increase in sexual activity and number of different partners, and the incidence of sexually transmitted diseases skyrocketed. Syphilis reached epidemic proportions by the late 1400s.

Syphilis represents an important concept in the propagation of infectious diseases: opportunity. A change in opportunity can change an endemic infection into an epidemic. Syphilis is caused by the same organism that causes the childhood skin disease yaws. In yaws, the infection is relatively benign and transmission can be infrequent. Syphilis, on the other hand, is a direct result of a much more complex human ecology. The same organism, provided with greatly differing opportunities, can yield very different disease states. In this case, the organism did not change. The changing agent was simply human behavior. This also exemplifies the impact human beings can have on their environment, which in turn impacts the existence of humankind. We are at once both active and passive players in the struggle for survival.

With our newfound optimism about our ability to control disease and not merely be its victim, humankind set out on two great eradication schemes: to rid the world of smallpox and to rid the world of malaria. Smallpox was successfully eradicated, but fifteen years after the initiation of the malaria eradication programs, malaria incidence worldwide was about 2.5 times what it had been before the program was started. The reason for these results was do in large part to the differences in the diseases themselves and demonstrated humanities inability to control to any great extent the environment in which we live, in this case the ecosphere of planet earth. Thirty years later, AIDS would also show humankind our inability to control our own behavior in the face of a deadly epidemic. Will our frailty and fallibility yet overcome our ingenuity and our drive to survive?

Emerging diseases are dependent upon many factors, some of which include:

1) transmissibility how effective is the organism at moving from one host to another
2) life cycle of organism the length and progression of the life cycle will directly affect the course of disease, and for any infectious pathogenic organism to survive long-term, it must reach some type of equilibrium between virulence, transmission and propagation
3) virulence / mode of transmission how contagious is the organism: as is evident, highly contagious organisms will tend to move through a population faster if given the appropriate opportunities, and the capacity for transmission will influence the course of the disease; virulence cannot exceed the length of the life cycle necessary for transmission
4) agricultural / industrial development provide for stable populations, but not necessarily for healthy populations: increasing the agriculture and industrial base makes possible increased urbanization which has an inherent tendency to promote disease transmission because of congestion and sub-optimal sanitation
5) environmental / ecological factors dynamic living situations directly impact and change the environment which can potentially disrupt the established equilibrium; destruction of natural habitats upsets balance and can cause potential disease-causing microbes to emerge from naturally secluded habitats; examples include: deforestation/reforestation, changes in water ecosystems, flood/drought, famine, global warming
6) demographic and behavioral factors the most important factor in the transmission of infectious disease is the fact that humans do not live within a set of behavioral parameters that optimally promote health; infectious diseases tend to arise when demographic changes disrupt an established balance, as when there is rapid population growth
7) modern travel in the age of global travel, migration and commerce has become the single greatest factor in contributing to a potential spread of an outbreak of an infectious disease and the generation of an epidemic: there is no place left on the globe that is immune to what occurs anywhere else
8) evolutionary changes evolution of infectious disease agents depends upon the same principles of variation, selection and fitness as in higher organisms; the genetic / metabolic integration of these agents into host cells can mediate subtle cumulative evolutionary changes in the host; disease emergence can include evolutionary changes taking place simultaneously or additively on different levels such as genotype, phenotype and the environment
9) breakdown in public health measures many factors can influence this from war to political instability to lack of funds

Once the factors for the emergence of a disease have been satisfied, further factors, are able to influence the progression and evolution of the disease. Changes in the environment can disrupt newly established disease equilibriums by altering selective pressures and constraints. Changes in social interaction may result from the disease, which may further exacerbate or diminish the progression of the disease. Random and directed mutation will alter an outcome, and changes in local and regional environment will favor directed mutation. Passive selection, where first priority is to propagate and perpetuate, will favor increased fitness. Active selection, such as the development of antibiotic resistance, will also favor increased viability, with the difference between the two being that the second is artificially imposed.

Emerging infectious diseases can be both "new diseases" and "old diseases emerging." However, most diseases newly described as emerging infectious diseases are the result of a pathogen that is itself not new. "Most emerging infections appear to be caused by pathogens already in the environment, brought out of obscurity or given a selective advantage by changing conditions and afforded an opportunity to infect new host populations (on rare occasions, a new variant may also evolve and cause a new disease)." (Morse) In fact, infectious diseases are still broadly endemic and maintain a large reservoir of capable agents that have the potential for rapid and widespread dissemination if provided with the conditions to do so. Reemergence of a previously "controlled" disease may result from the development of antibiotic resistance. Emerging diseases result because the opportunity to do so presents itself. This cannot be viewed as a purely chance and random occurrence. Even if a microbe mutates so that it has now obtained new functions, it must still be provided with the opportunity to transmit itself into an acceptable host. Emerging infectious disease cannot be a uniorganismal process. For example, a normally non-pathogenic organism may become so if provided the opportunity in an immune-compromised individual or in an individual who has a naive immune system to this organism.

It is possible to take preventive measures against emerging infectious diseases.But it is only possible to do this by directly addressing the general principles involved in health and disease, some of which include:

1) sanitation improve the elimination of waste and take measures to improve the quality of drinking water
2) contact decrease risky behavior and decrease unnecessary exposure to potential infectious disease agents
3) poverty tends to bring with it decreased standards of living, decreased hygiene and decreased sanitation
4) human rights the circumstances that promote emerging infectious diseases are often the same circumstances that are generated by a lack of human rights
5) immunological vulnerability this can be caused by a variety of factors including increased aging in a population, immunosuppression from other diseases, artificial prolongation of the lives of those that already have disease and new living situations; a consequence of increased vulnerability is that organisms previously considered harmless are now causing disability and death
6) other species what happens to other species, as in massive die-offs, may hold valuable information regarding potential risks to humans; population dynamics of other animal species should be monitored closely

So where do we go from here? How do we begin to address the issue of emerging infectious diseases? Is there really a problem, or have we just become better at identifying diseases and so see more of what has always been there? And are these fluctuations "normal" in the course of centuries and millennia or are we seeing what is apparently more than the previous fluctuations? I believe that what we are seeing reflects our changing world and is different only in scale and not fundamentally different in scope than that which has always gone on before. And it may very well be that humankind will be able to keep coming up with new and ingenious ways of keeping the emerging diseases somewhat in check. For instance, antibiotic resistance occurs more often in antibiotics from nature than in de novo designed antibiotics from the laboratory. As our understandings of the molecular mechanisms of disease continue to deepen, we will undoubtedly be presented with new possibilities for dealing with these diseases. Traditionally, western medicine has viewed the human being as the center of treatment and the environment as full of microbes that can invade the body and cause disease. Medicine has sought to eradicate these microbes and eliminate the diseases caused by them. "We adopted a way of thinking about infectious diseases predicated on a sequence of identification, intervention, and control or eradication of the pathogen." (Wilson) An alternative view envisions a more complex and interconnected world where most organisms, if not all organisms, serve some beneficial function. We may some day achieve the subtlety of modulating and controlling in a limited fashion microbes that cause disease rather than simply trying to massively exterminate them, which will upset some previously established balance. Could it be that some day we will be using organisms that presently cause disease to carry future exotic cures for other diseases? We may come to find that our interconnectedness to even disease-causing microbes is such that even while causing disease there are other beneficial aspects that these microbes bring to the overall balance of the world.

What are the implications, socially, philosophically and ecologically, of emerging infectious diseases? The positive and negative pressures and restraints that have maintained the present homeostasis are shifting to some new equilibrium, which is in itself neither good nor bad. It may be that a new level of infectious disease will arise and that humankind may find that this different physical state places newfound restrictions on the freedom of its existence. Perhaps it is a natural shift in an environment beleaguered by over-aggressive assaults by its human inhabitants. It should be emphasized that any change in the environment or a subset of the environment, such as emerging infectious diseases, is a natural phenomena that may appear to humans as unnatural because it deviates from the perceived and expected norm. The cause may not be "natural" but the resultant environmental reaction is always natural.

What are the theological implications of emerging infectious diseases? What are the implications regarding the status and stature of humankind in the world? What and where is God in this process? It has been vociferously argued both for and against God playing any role in the physical struggle for survival. Does God influence the physical forces of nature or manipulate the intrinsic laws of matter or is there a price extracted for humankind's physical and spiritual autonomy and the freedom to choose our own life? If God overtly or even covertly controlled the physical world, would we be free agents too choose our own destiny? If God is not involved in controlling the physical universe, no disease could be interpreted as an act of God. If we are all sinners, as many religious traditions insist, but only some of us are afflicted by a given disease, how can we rationally draw any conclusions from this? Precisely because we are fallible, we end up projecting our own individual social morals and religious judgments onto others, and incorrectly interpret these projections, which arise from our own attitudes, as the will of God. If one takes the position that God plays no role in the physical process of disease, whether it is a random mutation in a chromosome arising from the forces of physical chemistry and resulting in cancer or an adaptive change in a microbe that makes it more adept at causing disease, this is not paramount to rejecting the existence of God. God can be present, for those so inclined, in the experience of suffering, in the emotional and spiritual journey of hardship, in the search for grace and the desire for love. God can exist within oneself, and God can exist in personal relationships, in our interactions and perceptions of life.

I believe we are moral creatures and that there is some longing in us for meaning and purpose and righteousness. We want to help each other out of a sense of generosity and good will and altruism. Our relationship to God and to each other does not have to change in the face of increasing emerging infectious diseases and/or a change in the status of humankind resulting from dynamic flux in the present equilibrium of the physical biological world. This is not an apology for fatalism but a call for clarity, for objectivity in taking stock of the present status and potential future directions of the physical world in which we live. Realism, as opposed to dogmatism, may also help us to examine our present behaviors and actions and determine how we might lesson the factors influencing emerging infectious diseases, which in turn influence the status of humankind.

John S. Yordy
College of Medicine