LOUSE FEEDING EXPERIMENTS UPON 

 TYPHUS PATIENTS 



EXPERIMENTS DONE TO ASCERTAIN THE NATURE AND 



INCIDENCE OF MICRO-ORGANISMS ACQUIRED BY 



LICE FROM TYPHUS CASES 



1. METHODS OF FEEDING 



THE lice used were enclosed in boxes as described in the sec- 

 tion on "Technic." Thirty to forty lice, usually larvae and 

 nymphs, were placed in each box. The immature stages were 

 used to avoid the too great increase in numbers and consequent 

 danger in handling the boxes, which would result if adults were 

 employed. Also, if adults were used some would die from old 

 age before the termination of the three weeks usually allowed 

 for feeding; while their progeny probably would have fed for 

 too short a time to permit the development of a heavy infec- 

 tion in them of any organism derived from the patient. 



Fifty-two experiments were carried to completion in a series 

 of sixty-five. In the first six experiments the louse boxes were 

 left continuously attached to the patients for the whole period 

 of feeding, six to nine days. This method was discarded for a 

 number of reasons: it caused discomfort to the patients, it pre- 

 vented close supervision of the boxes containing lice, and it 

 gave the lice but one opportunity to feed during the early days 

 of a typhus infection when the blood is said to be most infec- 

 tive (Nicolle, 1920), (von Prowazek, 1915-16), (da Rocha- 

 Lima, 1919-21). 



In all experiments, after the sixth, the lice were fed twice 

 daily, morning and evening; the boxes being left in position for 

 one-half hour to an hour at each feeding. The patients se- 

 lected for the feeding experiments were all clinically well- 

 established cases of typhus and, as far as possible, in the early 

 stages of the disease. 



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