Since 1902 it has been generally recognized that Rocky Mountain spotted fever is a disease that prevails in certain localities in the Western States. As a result of researches, notably those of Wilson and Chowning, Ricketts and his associates, and of representatives of the Public Health Service, we now have definite knowledge as to the means by which the disease is spread from individual to individual and from one locality to another. A recent report5 by the Public Health Service on this disease shows it to be present in nine Rocky Mountain and Pacific Coast States. Cases have been reported during more than one tick season from certain localities within these states, and these localities are recognized as being definite areas of infection; that is, they harbor infective wood ticks capable of transmitting Rocky Mountain spotted fever to human beings by their bites.
Outside of the Snake River Valley in