The Evolutionary Origins of Smallpox - Essay Example

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 range of animal species throughout the world for millennia. Orthopox viruses include cowpox and chicken pox. Humans can be infected by some of these pox viruses, but none are as deadly as smallpox (Peters, 2004). When seen under an electronic microscope, Variola looks like a brick-shaped or elliptical classic form consisting of two strands of DNA (Barnes, 2007).

They represent the largest and the most complex of the pathogenic viruses. It is one of the largest and most complicated viruses known, thus, so lethal and difficult to combat. When the Variola invades the human cell it, is forced to reproduce the virus until there are hundreds of thousands of viruses within the cell. When the cell can no longer contain the viruses, the cell bursts. The viruses shower onto other cells infecting them (Glynn & Glynn, 2004). 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 absorb particular nutrients from the cytoplasm needed for its replication (Barnes, 2007). Origins of the disease The question of the origin and evolution of human smallpox virus was difficult to address. No one definitely knows when, where or how the first occurrence of the smallpox virus on earth happened.

Even within documented human history, it is difficult to trace the forms of smallpox origins and ascertain its development completely. All kinds of plagues, rashes and pox diseases, as well as other diseases, were mentioned interchangeably. The earliest unscientific descriptions of the symptomatology do not sufficiently differentiate various kinds of ailments (Koplow, 2004). Even in the modern era, particular differential diagnosis has continued to pose a challenge as smallpox can evolve as numerous distinct types of diseases from time to time, until laboratory findings confirm the innitial clinical impressions.

There are several explanations which have been expressed in attempt to explain the origins or beginning of the human version of the virus. Peters (2004) claims 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 them in other ways, and at some point the virus may have jumped from rodents to humans. Koplow (2004) suggests that the small pox virus might have originated from arbitrary mutation of some other less virulent and even older subspecies of unknown virus.

This might have happened 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