SPIROCH^TA RECURRENTJS 121 



passed into the body cavity, which swarmed with spirochaetes. The 

 contents of the alimentary tract and the faeces of the lice alike were 

 uninfective. The spirochaetes did not reappear in the gut till eight 

 days after an infective feed, but some persisted as late as the nineteenth 

 day when kept at 28 C. 



It was noted that the irritation due to the lice caused scratching, 

 and that thereby lice became crushed on to the skin. An emulsion 

 was made of two infected lice and rubbed on to the slightly excori- 

 ated skin of one of the above workers. Infection followed five days 

 later. A drop of emulsion placed on the conjunctiva of the human 

 eye produced spirochaetosis after an incubation of seven days. The 

 body contents of such lice, then, produce infection when they reach 

 the blood by any excoriated or penetrable surface. The stages leading 

 tip to infection in nature briefly are : The irritation due to the louse 

 bites causes scratching, and the lice are crushed on to the skin. The 

 slight abrasion is quite sufficient to permit the entry of the parasite. 

 The louse bite alone is harmless. Infection by way of the eye is 

 quite probable in Africa, remembering the constant trouble due to 

 sand, dust, insects, etc., resulting in frequent touching of the eyes. 



The spirochaetes occur in the body fluid of the lice and can pass 

 in it to the adjacent organs. Thus they probably find their way into 

 the genital organs, and into the eggs of the lice. Eggs laid twenty 

 to thirty days after the parent became infected have retained the 

 infection, and the larvae issuing from such eggs must have contained 

 some form of spirochaetes, for an emulsion of either the eggs or 

 the larvae produced spirochaetosis when inoculated into monkeys. 

 Further details regarding the spirochaetosis in the eggs of the lice and 

 in the larvae are needed. Hereditary infection, however, has been 

 demonstrated, but is not very common. Sergent and Foley (1914) 

 state that the spirochaete possesses a very small and virulent form 

 which it assumes during apyrexial periods in man and during a 

 period following an infecting meal in the louse. Nicolle and Blanc 

 (1914) find that the organisms are infective in the louse just before 

 they reappear as spirochaetes. Nicolle and Blaizot found that female 

 lice were more susceptible to spirochaetes than males, four times 

 as many females as males being infected. 



Tictin (1897) found S. recurrentis in bugs recently fed on patients, and infected a 

 monkey with the fluids of crushed bugs. Karlinski (1902) found the spirochaetes 

 in bed-bugs in infected houses. There is some other evidence to show that bugs 

 may transmit the spirochaete in Nature. Further researches are needed regarding 

 the relationship of bed-bugs and human spirochsetosis. 



Multiplication of S. recurrentis is by longitudinal and transverse 

 division (including so-called ''incurvation"), and the organism forms 

 small, ovoid bodies ("coccoid" bodies) in the same way as S. duttoni. 



