PRELIMINARY REPORT ON THE WOOD TICK 



Dcniiacciitor sp. 



The adnnral)lc work of Dr. II. T. Ricketts of the I'nivcrsity of 

 Chicago in Missoula and the Bitter Root valley has established the 

 fact that the wood tick found in that region is the means of man"? 

 infection with the Rocky Mountain spotted fever. He has shown i-^ 



1. That the period of activity of the ilisease is limited to the 

 season during which the adult female and male ticks attack man. 



2. That in practically all cases of this disease it can be shown 

 tliat the patient has been bitten by a tick. 



3. That the period between the tick bite and the onset of the 

 •disease in the many animals he has experiftiiented with corresponds 

 very closely to this period as observed in man. 



4. That infected ticks are to be found in the locality where 

 the disease occurs. 



5. That the virus of sjiotted fever is very intimately associated 

 with the tissues of the tick's body as is shown by the fact that the 

 female passes the infection on to her young through her eggs, and 

 fi;rther, by the observation that in either of the two earlier stages 

 of the life cycle the disease may be contracted by biting a sick 

 animal and communicated to other animals after molting or even 

 after passing through an intermediate active stage. 



This chain of evidence, given in full in Dr. Rickett's report, is 

 sufficient proof of the truth of the "tick theory" of the transmission 

 of the disease. 



In the public mind the question at once arises: — Since we have 

 wood ticks in other parts of the state why do w'e not also have the 

 spotted fever? The answer is that in other parts of the state the 

 ticks do not have the infection and hence cannot' transmit it. Dr. 

 Ricketts states in his re])ort that several hundred ticks were collecr- 

 cd from nature in the vicinity of a case of spotted fever and were fed 

 on normal guinea pigs and that only a small portion of them trans- 



*Ricketts, H. T., Spotted Fever Report No. 1. General Report of tlie 

 Investigation of Rocky Mountain Shotted Fever carried on during 1906 and 

 1907, published by State Board'of Health, Helena, Montana. 



