Disease and Migration


This paper is aimed at discussing the role that diseases played in migration. The discussion will be based on three authors: namely William McNeill, Sheldon Watts and Mary Dobson. There is a case in history that has been analyzed in great detail by Hernan Cortes. He was a war hero and who had very many battles under his belt. But the case of his imminent defeat in present day Mexico City in 1521 formed the greatest basis from which this case is analyzed. In this particular case, he was waiting to be attacked but due to some reason, his invaders never came. Eyewitnesses who brought him report after report had accounts that were disturbing. Mainly, they reported that the city was filled with heads and corpses of people who had been pillaged by a greater power than they had envisaged. They further reported that they had heard of a plague in Jerusalem but it was not as great as that witnessed in that city. Therefore, the odors that emanated from thence were so bad that one was offended a long distance away. When Christopher Columbus went to America with the Spaniards, the population was placed somewhere at 50 million people but afterwards it was reported to being less than 3 million people. This means that the plague that was gotten from Mexico City by those in battle had made it to areas where there was no infection reported.  Historians like Davis Brion termed this occurrence as the greatest genocide in human history. This case study shows that the greatest carnage, at least by Brion, did not occur due to the barbarism of Europeans fighting for the scramble of America but by the presence of microorganisms.


According to the present studies on all microorganisms including bacteria, viruses and fungi, they are not meant to be destructive to humans. In fact, they compete much in the same concepts that were advanced by Charles Darwin. This means that rather than destroy the hosts that they live in, they would rather reproduce and multiply in the host without bringing harm to the said host. However, when people move from place to place, they tend to meet others who have not been previously exposed to the same strains of these organisms. This means that the hosts usually take a lot of time before they get used to the presence of these organisms in their bodies. In the process, the hosts that are weaker than others tend to die off. In this instance, the population is greatly reduced since the actions of nature are evidentially in play. A sort of mutual tolerance arises for the parasite causing the plague in the stronger hosts. The result of such a process is that those who are tolerant become immune to the disease. Ultimately, the children that they give rise to become stronger and the illness is a common one to them without any devastating effects. William McNeill observes that the more diseased a population is, the less the epidemic to them.

   The university of Chicago historian, William McNeill, is credited as the first major contributor to the history of diseases even though he was not in the medical profession and did not therefore place it in a medical context. The context of his assumption was mainly in Europe although back hen every publication was either in Europe or in America. Before the publication of plagues and Peoples in 1976, most of the previous works had been by antiquarian medical practitioners who were mostly retired. However, the format of their publications tended to be more of a self-congratulatory nature although the intentions were good. However, the point of departure of these earlier works from those of William McNeill was the fact that they tended to be more on the presently occurring events and analyses rather than those of history. Additionally, all these works tended to be more focused on the sub discipline of history commonly referred to as history of medicine. The latter publications aside form the plagues and peoples tended to be more recognizable as addressing more on the historical perspectives and hence were considered to be intellectually respectable. At this juncture, it is worth mentioning that one of the works that could be considered as falling under this category is that by Sheldon Watts referred to as Epidemics and History: Disease, Power and Imperialism which was published in 1997. The fundamental difference between McNeill and Watts is that the latter is considered as advancing principles that would not be received politely by the medical social historians. Watts mostly defines his disease constructs as being culturally filtered. Furthermore, Watts’ claims are very precisely placed in time and place and are disease specific. However, the most misunderstood concept is the fact that the diseases are constructed in the context of being by agents of imperialism.

   In much detail, the book by Watts is a look at the way that human beings have been affected by a wide variety of scourges (5). Although the author is primarily a historian, he is much more of a cultural historian and also a social historian. Therefore, his travels and teachings have been more on the spread of diseases in the world and the way that the imperial regimes have been affected by the presence of these diseases. It further goes to show how those that the diseases targeted changed through time and also how those diseases changed the political as well as the medical class. His works are focused on the continents of Africa, Europe, Asia and the Americas. His major argument however was the fact that westerners did not have the capacity to cure the diseases which they had engendered through their expansion but also that the empire used its medicines as a way of expanding. He exemplifies his positions through the comparison between the pre-modern and modern way of practice in the medical field by examining the plague that raked Western Europe and part of the Middle East as well as leprosy which was very rampant in the 19th century tropics. Furthermore, he examines the impact that violent environmental changes had on the diseases and also the impact of the diseases on the society. In more detail, Watt aimed at deciphering the effect that plagues had on the physical aspects of human beings as well as on their minds. The context through which these facts are examined is that of both the rulers and the ruled.

   On the other hand, Plagues and Peoples was mainly a book that has earned acclaim in the medical as well as historical world since it focused on how diseases were perceived during the times when power was seized by force. The most profound thing that astounded many people in those battles was the role that smallpox played in Mexico. Additionally, there was a Chinese epidemic occasioned by the bubonic plague and also an experience of typhoid in the European continent. All these were contained in the original publication. However, when AIDS started being termed as an epidemic in the 1980s, McNeill added a new chapter in his book. The scope of his publication was however narrower than that of Watts in the sense that the periods and the diseases in history were not as many as those covered by Watts. Compare that McNeill covered only smallpox, bubonic plague and typhoid before he added AIDS with the diseases that Watts covered ranging from leprosy, plagues in Western Europe, smallpox, syphilis and other non sexual diseases that occurred due to the connection between Asia and Europe, cholera which was very rampant during the British occupation in India and the Atlantic bout of malaria that occurred during the periods of social Darwinism as well as during slavery.

   As shown by the discussions above, the major emphasis for Plagues and Peoples was how the new historians and medical practitioners focused on new infections while loosing the plot on the analysis of the old diseases. Although there was a scare in the 1970s when infections that were largely unexamined surfaced including swine flu, legionnaire’s disease as well as Lyme disease these conditions were not largely researched on and some have even remained as challenges in today’s world. In addition, during this period, the largely untouched ecosystems and forests in third world countries were being disturbed thereby bringing out pathogens that were formerly hidden. Perhaps the most unsettling period during these occurrences was the spring of drug resistant strains of many diseases that were formerly curable. Perhaps what the book by William McNeill best exemplified was that while the world changed, so did the circumstances that characterized it (74). All the occurrences that have mainly led to the presence of these disease challenges have been as a result of the symbiosis and competition that is inevitable within the ecosystems and also without them. The book is enlightening on how the movement and transition of humans from being fundamentally nomadic, to them being based on agriculture and eventually urbanization which stemmed from industrialization affected how the diseases changed. It is interesting to note that a careful review of the book suggests that diseases like tuberculosis, smallpox and cholera occurred through the mutation of microbes from those affecting animals in the previous centuries. Most notably, dog measles, water buffalo leprosy, cattle infections and chicken influenza were all agents of disease causing organisms in human beings. Activities like the large-scale cattle rearing which warranted that people live together with animals made it possible for pathogens to jump to other hosts.

   The book Epidemics and History has been viewed as very informative in the influence of the way that diseases are understood in the modern world. Most reviewers term the book as being free of all the jargon that is synonymous with many other authors that touch on the topics of plagues. The writer Watts has coined some phrases that are now widely used. For example, most people consider the germ theory as a theoretical construct and also that diseases are largely viewed as both social constructs and also as biological constructs. However, the writer does have a blemish as he attempts to add a yellow fever construct and a leprosy construct. This does not sit well with many critics as they consider this as being a minor detail and one that does not deserve as much attention as it is accorded. What the other wanted to emphasize by adding such controversial points is that these had political and social connotations. However, those that disagree with this viewpoint concede that what Watts should have done is to simply state that h wanted to point out the social and political impacts of plagues and diseases rather than coating them as constructs in themselves. The responses, either political or social, for the plagues seems to be the point of consensus that Watts should have focused himself on rather than on constructing complicated theories. Moreover, some reviewers concede that the book has some oversimplification of matters as the attribution of modern scientific medicine should not have been simply dismissed as the work of Robert Koch. The problem that arises from this notion is that while people being blamed for undertakings in their areas of specification is common in the world today, a consequence of this book, it is something that should have been considered in detail as the focus on medicine rather than on the suffering of those that need the medicine is not ethical.

Present and future

   The book Plagues and People had a profound impact on the modern medicine. One would have thought that the discovery of antibiotics would have been the end of a majority of scourges in the world today. Contrary to that popular belief, many of the plagues still dog the modern world. This proves that the book Plagues and People was not constructed for the short term but rather as a blueprint for the long run. This is because the advancement of people has been accompanied by a larger group of ailments and also by more complex strains of former diseases that were easily curable. The presence of AIDS should be an indicator that most of the activities of humans have led to even bigger plagues. Although the condition is manageable in the world today, it remains to many especially those in sub-Saharan Africa as one of the deadliest killers of all time. Additionally, the fact that some strains of malaria especially those that do not respond to common medication largely based on penicillin have emerged is an indicator that plagues have continued to be a challenge to people as they continue to advance. Today, malaria related complications are treated with sulphur-based drugs which have cost researchers a lot in term of resources and time. In addition, people who have severe cases of tuberculosis have had to be isolated from others with the normal strain of TB so that the drug resistant strain does not continue to be prevalent.

                In support of both theories that have been developed by McNeill and Watts, governments today tend to use healthcare and the presence of plagues as a way of gaining political mileage. Consider that most scourges today are as a result of cultural, social, political and, economic factors. This means that that as a consequence, the above factors are associated with gender relations, poverty, urbanization, inequality and all other factors that may play apart in the transmission of a disease from one person to another. Biotic and social factors are the most contributory factors in the emergence of infectious diseases. Today, it is very easy for diseases to advance since the social trends allow for it to be so. What both writers advance is the fact that if it weren’t for the development of people, then there wouldn’t be an advancement in plagues. More profoundly, there is the fact that people have advanced in technology and as such, bioterrorism is a possibility. This factor alone may not be a major contributor to the advancement of plagues. This has the possibility for plagues to be very serious and in turn, the development of antiserums that may alleviate these plagues may pose a challenge. Additionally, there is the challenge of the already existing plagues that have not been advanced by man. For example, Ebola which is a common occurrence in central Africa may be laboratorized and its effects amplified. Most recently, there was the SARS epidemic that threatened to annihilate man had its effect not been quickly contained through quarantine in the areas that it occurred. All the above factors prove that there will always be the development of plagues as long as there is existence of human beings. This is in support of the theories that have been advanced by William McNeill. There is also the fact that there will always be epidemics as history has proven over time as advanced by Sheldon Watts.

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