712 THE BLOOD-INHABITING SPIROCH^TES 



therefore is the same as was shown by Leishman and by Hindle to obtain 

 in the case of S. duttoni and Ornithodoros moubata. These observers have 

 also been able to demonstrate that hereditary infection occurs in the body 

 louse, an important fact which proves that this insect is a true intermediate 

 host for the spirochsete. Attempts to transmit the spirochsete to monkeys 

 by means of the tick Ornithodoros savignyi obtained in Tripoli completely 

 failed. In one experiment Nuttall demonstrated that A. lectularia fed on an 

 infected mouse and immediately afterwards upon a healthy mouse trans- 

 mitted S. recurrentis from the former to the latter.] 



Relapsing fever also occurs in Asia India, Persia, China and other parts 

 and in that continent the disease is apparently propagated either by the 

 parasites mentioned above or, as in Persia, by a tick the bug of Mianeh, 

 Argas persicus. 



In [West and] East Africa relapsing fever is known as Tick fever. 

 Lafforgue has described a similar disease in Tunis. Tick fever differs some- 

 what from the European disease chiefly in being much more fatal and in 

 the fact that the fever is of shorter duration and the spirochsetes are less 

 numerous in the blood of the peripheral circulation. The African fevers are 

 conveyed by a tick (Ornithodoros moubata) which only bites at night. This 

 disease was described by Dutton and Todd, Kudicke, Koch and others. 



[In the case of S. duttoni the tick produces infection only as a result of the 

 entrance of the infective excreta into the wound produced by the bite of 

 the insect (Leishman, Hindle).] 



In the tick the spirochsete multiplies on the surface of the ovary and passes 

 into the egg and young embryo. 



[Leishman found that S. duttoni breaks up into minute masses of chromatin 

 " coccoid granules" in the ova and tissue-cells of the tick Ornithodoros 

 moubata and it would appear that these coccoid granules again develop into 

 spirochsetes. 



[Hollers has shewn that ticks may remain infective for as long as 1J years after 

 their initial feed upon an infected animal. " Hollers has, moreover established the 

 fact that infected ticks fed on six successive clean animals may, following upon 

 each feed of blood, lay six successive batches of infected eggs, from which issue young 

 ticks capable of transmitting the spirochsete to experimental animals. Even more 

 remarkable is the fact that the ticks may remain infective to the third generation 

 the ticks throughout the second generation having been fed upon clean animals." *] 



Relapsing fever also occurs in America and especially in the United States. 



At the present time opinion is in favour of regarding the spirochsetes found 

 in relapsing fever in different parts of the world as belonging to different 

 species (Novy and Knapp, [Nuttall], Frsenkel and others) of which the 

 following are distinguished. 



Spirochceta recurrentis ( =obermeyeri), the spirochsete of European relapsing 

 fever. 



Spirochceta duttoni, the spirochsete of [West] African relapsing fever 

 (Tick fever). 



Spirochceta novyi, of American fever. 



Spirochceta carteri, of Indian fever, which however seems to be very closely 

 related to S. recurrentis. 



[Spirochceta rossii (S. kochi), the parasite of East African relapsing 

 fever.] 



For the present the various spirochsetes are differentiated by biological 

 tests ; the differences in morphology and in the diseases produced by experi- 

 mental inoculation being in many cases very slight. 



t 1 Nuttall, Harben Lectures 1908.] 



