MIRAGLIA AND BERRY 



The extent to which exposure of experimental animals to low en- 

 vironmental temperature alters or modifies the outcome of host- 

 parasite interaction is not clearly extablished. Pasteur , nearly a 

 century ago, attributed the resistance of chickens to anthrax to the 

 characteristically high body temperature of fowls. By inducing hypo- 

 thermia he was able to render them lethally susceptible. In the 

 intervening years, reports dealir^ with the effects of cold on the 

 course of bacterial infections have been few in number. On the 

 other hand, literature concerned with the physiological effects of 

 exposure to low temperwtures on various mammalian species is 

 extensive, including several reviews (Hemingway, 1945; Hardy, 

 1950; Hardy, 1961; and Smith and Hoijer, 1962). 



There are, nevertheless, important studies on the contribution 

 of the environment to the response of animals challenged with 

 several different infectious agents. Junge and Rosenthal (1948), for 

 example, studied the survival of mice infected with pneumococci 

 and reported increased susceptibility when the temperature was 

 decreased to 18° C. It was necessary, however, to treat the animals 

 with salfadiazine immediately following infection in order to insure 

 sufficient survival to make the temperature effect apparent, 



Muschenheim and collaborators (1943) had studied several years 

 earlier the effect of hypothermia in rabbits on resistance to experi- 

 mental pneumococcal infection. When a highly virulent strain was 

 employed, the only demonstrable effect of lowered body temperature 

 on host response to the pathogen, compared to that in normothermic 

 animals, was a decrease in the local inflammatory reaction. When a 

 strain of low virulence was used, the induced hypothermia resulted 

 in bacteremia and death in Addition to the inhibition of the dermal 

 inflammatory reaction. 



The interaction between certain viruses and a variety of hosts as 

 influenced by environmental temperature has received considerable 

 attention in recent years. The incisive investigations of Boring et al. 

 (1956) are particularly germane to this paper. Cold was found to 

 have an adverse effect on the mouse infected with a Cosxackie virus. 

 The animals were housed 8 to 12 per cage at 4° C without restriction 

 on huddling. At this temperature there was a viremia through the 

 fourth post- infection day while the blood was clear of virus by that 



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