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CHAPTER V 



VIRUSES AITD HUMAN WELFARE 



In any dlacussion of the relationship of disease to human welfare, one 

 naturally thinks first of those maladies of man which cause suffering, perma- 

 nent disability and death. When we take the world view of the importance of 

 diseases, one of the first that we think of is malaria. In spite of what is 

 known about its control and cure, it is estimated by some authorities that even 

 today as many as five million people die in a year of this disease. Malaria is 

 not a virus disease. However, several virus diseases stand high on the list of 

 killers. Though ordinarily relatively mild, ' influenza occasionally occurs in an 

 extremely severe form. It is estimated that during the 19lfl-19 influenza pan- 

 demic, as many as 1^ million people died of this malady throughout the v/orld. 

 Figures for the united States alone are estimated at 500.000. There was a time 

 when smallpox was a serious and constant threat to mankind. It was not uncommon 

 for smallpox epidemics to kill off from 10 to ^0% of a population. Indeed, some 

 of our Pilgrim fathers boasted of their own good fortune when this disease at- 

 tacked and destroyed up to ')0% of the Indism inhabitants of some sections of New 

 England. During the days of the slave trade, yellow fever epidemics v/ere common. 

 Thousands upon thousands lost their lives to this killer in tropical cities and 

 on board slave vessels. The mortality figures approximated ^0%, 



Diseases have many adverse effects upon hximan beings in addition to the 

 death and destruction that they leave in their wake. It is well recognized that 

 epidemics have often Influenced the outcome of military campaigns much more than 

 the strategy of the generals Involved. Indeed, it is estimated that at the time 

 of our own heroic defense of Bataan, 6^% of our men suffered from malaria. The 

 course of history is sometimes affected in seemingly subtle ways. There is con- 

 siderable much-quoted evidence that the Tudors of England suffered from syphilis. 

 Many people have speculated on the influence of the suspected syphilis of Henry 

 VIII upon the course taken by English history euid even upon the development of 

 the Protestant movement In that land. The political situation in India today is 

 Influenced by the prevalence of malaria. It is believed by some that, were this 

 one disease eradicated, India would evolve from one of the poorest nations on 

 the earth to one of the richest, and many of the political difficulties of that 

 country would then become adjusted, with or without the white man's guidance. 

 Malaria and the virus disease, yellow fever, effectively prevented tlie French 

 from building the Panama Canal. It was only after the Americans had learned how 

 to conquer these diseases that they succeeded wherein the Krench had failed. The 

 tremendous Influence of this event upon the subsequent rise of the United States 

 to a world power can hardly be appreciated by us today. 



Many of us fail to realize that the course of human events is affected by 

 diseases of plants and animals almost as much as by the diseases of man himself. 

 There are two ways in which diseases of animals are related to human welfare. 

 First, they often serve as reservoirs for human maladies. Second, the economic 

 well-being of man, particularly his ability to supply himself v/ith food, is oft- 

 en jeopardized. It might be well to recall what a terrific scourge tuberculosis 

 of cattle has been in this country. This disease was a constant source of dan- 

 ger to the human population. In addition to that, it caused the death of many 

 milk producing cattle. Tremendous sums of money were expended for its eradi- 

 cation. Fortunately, it seems now to be under reasonably satisfactory control, 

 iiost of us are familiar with diseases of household pets, particularly rabies and 



