The Evolutionary Origins of Smallpox (Essay Sample)

The Evolutionary Origins of Smallpox
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The Evolutionary Origins of Smallpox
The medical history of smallpox is a history of indescribable human anguish and suffering, surprising human ingenuity and eventually unprecedented human victory. Smallpox was a despicable sickness, spreading round the world from antiquity to modern-day times. It was spread by an obscured virus, it infected a single person as well as an entire community with extraordinary speed and it proved terminal to virtually one-third of its victims (Koplow, 2004, pg. 9). Those who by some means survived the painful forteen days period of fever, skin discharges and internal tissue damage were usually left with acute disfiguring and blemishing and sometimes sightless. There was no treatment.
This paper will outline a brief history of smallpox as a disease, giving a brief history of its underlying causal organism as well as its unique characteristics that make it a unique disease. Additionally, this paper will spell out the different explanations which have been forwarded by different writers to try and explain the evolutionary origins of smallpox as well as a brief explanation as to why it spreads to humans.
Introduction
Smallpox is caused by the Variola virus, a member of the orthopox virus family and one of the many pox viruses that have been infecting a large range of animal species throughout the world for millennia. Orthopox viruses include cowpox and chicken pox. Human can be infected by some of these pox viruses, but none are as deadly as smallpox (Peters, 2004, pg. 1). When seen under an electronic microscope, Variola looks like a brick-shaped or elliptical classic form consisting of two strands of DNA (Barnes , 2007, pg. 222). They represent the largest and most complex of the pathogenic viruses
It is one of the largest and most complicated viruses known, which may be what makes it so lethal and difficult to combat. When the Variola invades the human cell, the cell is forced to reproduce the virus until there are hundreds of thousands of viruses inside it. When the cell can no longer contain the viruses, the cell bursts. The viruses shower onto other cells infecting them (Glynn & Glynn, 2004, pg. 194). Then the process begins all over again. Unlike most DNA viruses that replicate within the nucleus of the host cell, pox viruses manage to replicate outside the nucleus within the cytoplasm of the infected cell. The virus sheds its double membranous coat once it gains entry into the host cell and slowly begins to absorbing from the cytoplasm selected nutrients needed for its replication (Councilman, 1970; Woolf, 1977; Barnes , 2007, pg. 222).
Origins of the disease
The question of the origin and evolution of human smallpox virus was difficult to address. No one knows definitely when, where or how the first occurrence of the smallpox virus first appeared on earth. Even within penned human history, it has prooved difficult to trace the forms of smallpox origins and development completely, in part for the reason that there lacked, until the modern-day era, a homogeneous and harmonized medical lexicon. All kinds of plagues, rashes and pox diseases as well as other pestilence were mentioned to interchangeably and the earliest scribes unscientific descriptions of the symptomatology do not continuously sufficiently differentiate the different kinds of ailments (Koplow, 2004, pg. 10). Even in the modern era, particular, differential diagnosis has continued being a challenge as smallpox can from time to time masquerade as numerous distinct types of diseases,including the accustomed chicken pox and more unusual novelties, until laboratory findings confirm the innitial clinical impressions.
There are several explanations which have been forwarded to try and explain the origins or beginning of the human version of the virus. Some of these explanations advanced include,
Peters (2004, pg. 4), stated that the Variola virus can be traced back to prehistoric times. In its early form it was a virus that primarilry infected rodents. However, prehistoric humans hunted rodents for food or came into conatct with it in other ways and at some point the virus jumped from rodents to humans. According to koplow (2004, pg. 11), the small pox virus may possibly have originated from a arbitrary mutation of some other less virulent and even older, subspecies of unknown virus, most probably around 10,000B.C, somewhere in the bountiful Ganges River plain in india. He insinuates that some moderately minor disease agents instinctively adapted and modified themselves from early domesticated and tamed animals or from inferior primates to human hosts. He ascertained that the viruses that instigate cowpox and monkey pox, are still identifiable as very close variola cousins today.
According to Villarreal (2005, pg. 344) smallpox, based on its earliest references found in Sanskrit texts, originated from from the indian subcontinent several years ago and spread into europe via North Africa during the Arabian expansion. He believes that it is highly likely that the smallpox virus initially evolved in another host and was able to jump species and establish itself as a succesful acute viral agent specific to humans.
However, the explanation that provides the best support for the evolutionary origin of smallpox and how it was spread to humans was provided by Barnes in his book Diseases and Human Evolution. According to him (2007, pg. 223) the Variola virus most likely originated in an animal population and jumped species when the opportunity presented itself for adapting to human beings. He recognized that the closest relative to the human virus capable of infecting humans is a similar pox virus found occurring naturally in West Africa monkeys. He added on that Monkey pox can cause sporadic infections in humans and its symptoms closely resembled mild forms of smallpox. Occasio...