SPIEOCH^TOSIS OF SUDANESE FOWLS 97 



indeed, one adopts the viow that the few bodies ingested broke UX3 into granules which, 

 thougli they did not nmltiply, were yet infective in that they were capable of invading 

 the red cells of any chick into which they were injected, and then undergoing their cycle DifiicuUy in 

 of schizogon\'. Perhaps sufficient tests have not been made and a certain proportion °'''^'"'"g 



^ ^ O. savigfiyt 



of O. savignyi may yet be found effective as regards spirochsete transmission. These ticks 

 have to be brought in by camel from an oasis some hours from Khartoum or sent by 

 post from Kordofan so it is not always easy for me to have a good stock in hand. 

 (The above supposition is probably correct as more recent work shows that the spirochaBtes 

 undergo the same preliminary changes in this tick as they do in A. persicus — they 

 shed granules.) 



(5) Can fowl lice (Menopon sp. ?) act as vectors'? If one could prove these ecto-parasites 

 to be carriers, yet another link would be established in the chain of analogy between 

 this variety of fowl spirochsetosis and certain forms of human relapsing fever (Indian and 

 North African). This has now been done. My earlier experiments were either negative or, 

 like the observations recorded in the Journal of Tropical Medicine and Hygiene of October 1, 

 1909, gave only indirect proofs. In this case lice were fed on a chick heavily infected 

 with spirochtetes and transferred on March 1, 1909, to a healthy, clean bird, which 

 was carefully protected from tick infestation. Owdng to press of other work this chick's 

 blood was not examined till March 5, when its red cells were found to harbour 

 bodies, no spirochaetes being found. It was chloroformed and an emulsion of its 

 liver inoculated into a third chick, which, unfortunately, w'as not a clean bird in that 

 it showed some bodies, but it happened to be the only chick available at the moment. 

 Examination of the liver of the second chick by the Levaditi-Manouelian method proved 

 negative as regards the presence of spirochfetes. What happened in the third chick is 

 interesting. On the day (March 6) following the inoculation of liver emulsion a huge 

 increase in the number of bodies took place. On the same date some drops of its 

 peripheral blood were inoculated into a fourth chick ; it was chloroformed and an 

 emulsion of its liver injected into a fifth chick. This fourth chick, which is the chick 

 mentioned on page 82, developed bodies eventually, died, and its liver was found to 

 contain spirochaetes. It may be said that the fifth chick also developed bodies and 

 died, but no spirochaetes were found in its liver. The weak link in this chain of 

 events is, of course, the fact that the third chick was not a clean bird. Still, the 

 results were suggestive, and made one think that lice might act as vectors. 



Eecently, Captain Archibald has carried out some experiments which, I think, Fowl lice are 



definitely confirm this view. Here is one of them : — vectors 



Junaitrn 10, 1911. Lice removed from a healthy fowl aud jilaeed ou a chick showing a heavy 

 spiroehiete iufection. No bodies present. 



Jaiiu'inj 12. Lice removed from the infected chick aud placed ou a healthy clean chick. Every 

 subscciucut day this operation was repeated up to Jctiiimnj 14. Some tweuty lice in all were used. Blood 

 e.Kamiuations negative till 



Jniitftrji 16, when a few spiroehietes were found in the blood of the chick on which the successive 

 batches of lice had been placed. 



Jaiiadnj 17. Heavy spirochaetal iufection. 



This bird eventually recovered without at auy time showing intra-corpuscular forms in its peripheral 

 blood 



An experiment of this kind does not of course determine the incubatiou period after louse-bite, but a 

 subsequent case supplied this information. 



Jammry 17, 1911. Two dozen lice from a chick suffering from acute spirochastosis placed on a healthy, 

 clean chick, which was protected from tick bite. Daily blood examinations proved negative until 

 Januarii 22, when the bird was found dead with spirochsetes in its heart's blood. The incubation period 

 would, therefore, seem to be about four days. 



Examination of the lice from this chick proved entirely negative both as regards the presence of 

 spirochaetes aud of granules, and in this respect resembled all previous examinations of lice. Hence 



