110 LICE AND THEIR MENACE TO MAN 



either by the microscope or by the reactions of 

 the blood. 1 At the present day it is most common 

 in Poland, Russia, Austria, and Eastern Europe 

 generally, the cooler parts of Asia, Northern 

 Africa, and Mexico. It is uncommon in Canada, the 

 cases which are occasionally reported there being 

 due to small foci of infection set up by infected im- 

 migrants, and the conditions in the country not 

 being suitable to widespread epidemics. The 

 same remark applies generally to the United 

 States, though it is definitely established in New 

 York, where it is known as Brill's disease. 



That the causative agent of the disease is 

 present in the blood was shown by Moczutovski, 

 who inoculated himself with such blood, suffered 

 from the sickness, and later unfortunately died 

 from the results of the attack. It was later 

 shown that monkeys and rabbits could be in- 

 fected with the disease by inoculation. 



In spite of much careful searching by many 

 brilliant workers the actual agent which causes 

 the disease, that is, the organism which must be 

 present, and multiplying in the body of the patient 

 to cause the intense blood-poisoning, has not yet 

 been certainly discovered. It is improbable that 

 this discovery will be long delayed. Various 

 organisms which have been found in the blood 

 or other tissues have at different times been 

 described as the causative agents, but no proof 

 has been forthcoming. 



1 The Weil-Felix reaction now appears to be an established test. 



