John W. Gowen, Ph.D. 



GENETICS of INFECTIOUS DISEASES 



For every disease there is a host species in which the disease is recognized. Since 

 individuals within species vary genetically in many ways, they, as expected, also vary 

 in expressing the syndrome for any particular disease. Similarly if the disease is 

 infectious, another species, pathogenic to the host species, is generally responsible for 

 initiating and carrying on the disease. The organisms within the pathogenic species 

 likewise vary genetically in virulence and other characteristics and, in consequence, 

 also lead to variations in their invasive power to individuals within the host species. 

 Some diseases further complicate the results by requiring other species, as mosquitoes 

 for malaria, for vectors to maintain and carry the disease to the host, thus adding further 

 genetic variables to the already complex situation. Different environmental agents of 

 many kinds likewise strongly affect the expression of disease in numerous ways. These 

 factors tend to confuse the data on causation of disease by inducing variation in disease 

 expression so that individuals may vary all the way from no expression through various 

 grades of morbidity to those that die. So far as is known, there are no problems of 

 genetics that offer more complications in their solutions than those pertaining to disease 

 resistance. The problems are, however, of interest because of the complexity, the 

 genetic implications and discussions brought about thereby, and the methodology 

 developed for their solution. 



Discussion of these problems will be limited largely to mice and only to certain 

 aspects of the host-pathogen relations as our investigations fall almost entirely within 

 this field. The research considered is largely that of associates and students who have 

 made extensive contributions to the problems. Papers giving a broader coverage 

 of the subject are listed in the bibliography. 



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