Man's Mortal Enemies 27 



After all, the fly is known to transmit the disease of pink eye 

 in cattle. 



But let's look at a few diseases that are no longer in the 

 realm of speculation. Rocky Mountain spotted fever is a 

 disease very much like typhus. It attacks hunters, campers, 

 and lumberjacks — ^people who go out into the woods and 

 fields. The organism of this disease, like that of typhus, be- 

 longs to the Rickettsiae family. In faa, it was Ricketts him- 

 self who proved that the bite of the wood tick was the means 

 by which men contracted the disease. But what animal was 

 the reservoir of the disease? Ricketts' death at the age of 39 

 brought to an end his brilliant investigations, but many others 

 took up the challenge, and during the past 40 years many 

 thousands of wild animals have been examined in attempts 

 to determine the culprit. One man who has trailed the elu- 

 sive killer for the past 25 years is William L. Jellison of the 

 U. S. Public Health Service. Jellison's investigations indi- 

 cate that the probable host is a rabbit, Nuttall's cottontail and 

 perhaps some related species. 



But don't get the idea that spotted fever is limited to 

 the Rocky Mountain region. This disease, or modified forms 

 of it, has claimed victims in at least 41 of our states, and it 

 has been spreading even to the cities. The summer of 1946 

 brought an attack of an eastern form of spotted fever to the 

 Borough of Queens in New York, where, during a period of 

 three months, 36 persons, ranging in age from three months 

 to 72 years, contraaed the disease. Undoubtedly, ticks 

 spread the disease. But did the ticks get it from an innocent- 

 looking cottontail, or did they pick it up from some other ro- 

 dent, or perhaps a domesticated animal? 



Worse than polio in its mortality is encephalitis — liter- 

 ally inflammation of the brain. This disease is world-wide 



