THE ROCKY MOUNTAIN SPOTTED-FEVER TICK, WITH SPECIAL 
REFERENCE TO THE PROBLEM OF ITS CONTROL IN THE BITTER 
ROOT VALLEY IN MONTANA. 
INTRODUCTION. 
For many years a disease of human beings, known as spotted fever, 
has been known to occur in certain localities in the Rocky Mountain 
region of the United States. In fact the evidence is rather conclu- 
sive that the disease existed before the settlement of the country by 
white men. At any rate old residents of the Bitter Root Valley in 
Montana have informed us that the first white settlers were warned 
by the Indians of the danger of contracting a very serious disease 
if they visited certain localities. From what has been learned in 
recent years it is evident that these dangerous localities are the very 
ones in which spotted fever is now most prevalent. 
The States in which the disease occurs most frequently are Mon- 
tana and Idaho. There is no doubt, however, that it occurs in at 
least portions of other States, such as Oregon, Washington, Nevada, 
Utah, Wyoming, and Colorado. 
Definite work on the nature and method of transmission of spotted 
fever was not begun until 1902. In that year Drs. Wilson and 
Chowning announced the theory that the “wood tick” is the natural 
agency through which the malady is transmitted from one human 
being to another. This hypothesis was based upon three observa- 
tions: First, that the majority of cases of spotted fever showed 
histories of tick bites; second, that the localities in which the disease 
was most frequently contracted were those where ticks were most 
abundant; and, third, that the season of spotted fever coincided with 
the period when the ticks were most frequently observed. Drs. 
Wilson and Chowning had no facilities for proving their hypothesis 
in a scientific manner, but such proof was soon obtained. Accord- 
-ing to the late Dr. H. T. Ricketts* the first experiments which re- 
sulted in proof of the transmission of spotted fever by the tick were 
conducted by Drs. McCalla and Brereton, of Boise, Idaho, in 1905. 
In these experiments a tick which was found attached to a spotted- 
fever patient was removed and allowed to bite a healthy person. In 
1Fourth Biennial Report, Montana State Board of Health, p. 106. 
