Chapter 1
History and Impact of Virology
Abstract
The foundations of the science of medical virology are intertwined with the other life sciences, particularly microbiology and infectious diseases. Medical virology has a relatively brief history, spanning just over a century, but it is crowded with intriguing discoveries, stories of immense personal courage and numerous practical applications, many of which have had an overwhelmingly positive benefit on humankind. Its origins involved the replacement of centuries-old beliefs and theories with discoveries borne out of rigorous scientific investigation. Targeted prevention and control strategies could only be developed and implemented once the concept of the specificity of disease causation had been accepted, namely that infectious diseases are caused not by some common miasma (a mysteriously poisonous substance), but rather by specific agents. In a wider sense, the microbial sciences have played a pivotal role in the development of medical thought, particularly in applying scientific rigor in understanding pathological processes. Advances in understanding of infectious agents have led to improvements in human health and well-being that arguably have exceeded the contribution of any other branch of science. Indeed, many workers in this field have been awarded the Nobel Prize in Physiology or Medicine in recognition of their achievements.
Keywords
Virology; history; virosphere; nature of viruses; microorganisms
Infectious disease is one of the few genuine adventures left in the world. The dragons are all dead and the lance grows rusty in the chimney cornerâŠ. About the only sporting proposition that remains unimpaired by the relentless domestication of a once free-living human species is the war against those ferocious little fellow creatures, which lurk in the dark corners and stalk us in the bodies of rats, mice, and all kinds of domestic animals; which fly and crawl with the insects, and waylay us in our food and drink and even in our love.
So wrote the great microbiologist Hans Zinsser in his book Rats, Lice and History, written in 1935, as he reflected on his life in infectious disease research. Zinsserâs thoughts have stimulated generations of students and professionals ever since. Infectious diseases of today present challenges that are different but just as demanding as those facing Zinsser over 80 years ago.
This book presents the subject of medical virology from the perspective of its traditional base as a life science and its application to clinical practice and public health. It is the perspective established by Frank Fenner and David White, who in 1970 conceived the rationale for this book, and maintained it through the previous four editions. It is the perspective that many others have used to teach and learn medical virology.
The foundations of the science of medical virology are intertwined with the other life sciences, particularly microbiology and infectious diseases. Medical virology has a relatively brief history, spanning just over a century, but it is crowded with intriguing discoveries, stories of immense personal courage and numerous practical applications, many of which have had an overwhelmingly positive benefit on humankind. Its origins involved the replacement of centuries-old beliefs and theories with discoveries borne out of rigorous scientific investigation. Targeted prevention and control strategies could only be developed and implemented once the concept of the specificity of disease causation had been accepted, namely that infectious diseases are caused not by some common miasma (a mysteriously poisonous substance), but rather by specific agents. In a wider sense, the microbial sciences have played a pivotal role in the development of medical thought overall, particularly in applying scientific rigor in understanding pathological processes. Advances in understanding infectious agents have led to improvements in human health and well-being that arguably have exceeded the contribution of any other branch of science. Indeed, no less than 35 workers in this and closely related fields have been awarded the Nobel Prize in Physiology or Medicine in recognition of their achievements.
Infectious disease discoveries have had a profound effect on life expectancy and well-being across the world. For example, epidemics of smallpox, yellow fever, and poliomyelitis, commonplace until well into the 20th century, have been virtually eliminated by the application of various prevention and control strategies. However, hitherto unrecognized diseases have emerged over the past half-century at the rate of at least one per year. Many of the viruses dealt with in this edition were unknown when the first edition was published over 45 years ago. The epidemiology of other viruses has radically changed as humans continue to alter the environment in so many ways. Meeting the challenges posed by emerging diseases requires the medical virologist to acquire ever more increasing expertise and access to ever more complex technologies. Today diseases such as HIV/AIDS, hepatitis C, influenza, and diarrheal diseases represent significant threats to public health. Tomorrow it will be other diseases, the nature and means of control for which are largely unpredictable. One positive note is that all emerging viral diseases of recent years have been found to be caused by members of previously recognized families of viruses. Thus a thorough knowledge of representative members of each family is likely to facilitate and inform the rapid development of knowledge about any new pathogen.
Why Study Virology?
As many bacterial infections have succumbed to treatment with antibiotics, viral infections now pose proportionally a much greater threat to global public health than was the case, say, a half-century ago. Viral diseases exact a particularly heavy toll among young children and infants in the economically less developed nations where healthcare resources are limited. Ironically, there is a resurgence of interest in viruses that target bacteria (bacteriophages) as an alternative strategy for the control of some increasingly drug-resistant bacterial infections (e.g., cholera).
Although this book focuses on viral infections of medical significance, the reader needs to be aware that viruses are a major threat to livestock and plant species, and thereby of great importance in human nutrition and food supply. Human adaptation to diseases of livestock and crops has played a major role in the development of all civilizations.
Virology is much broader than linking a particular disease to a specific pathogen: there are literally hundreds of new viruses being discovered that do not apparently relate to any known pathological condition of either animals or humans. Many of these may in the future be linked to human illnesses and thus the reader needs to be aware of the wider scope of the virological landscape, if not in detail at least to the point of âexpecting the unexpected.â Conversely, the tantalizing goal remains to clarify what role, if any, viruses may play in well-known diseases of uncertain etiology, for example, multiple sclerosis.
The vast majority of new viral threats emerging annually either originate from an animal host (zoonosis) or are the result of host range extension (that is, âhost species jumpingâ), or other changes in the epidemiology, ecology, and/or pathogen...