HUMAN SPIROCHJETOSIS 713 



SECTION I. EXPERIMENTAL INOCULATION. 



I. European relapsing fever can be transmitted from man to man by 

 inoculation (Munch, Metchnikoff, etc.). 



Carter and Koch have further shown that the apes of the old world can be 

 infected by inoculating them beneath the skin with the blood of an infected 

 man. The relapses which are so characteristic of the human disease are not 

 always reproduced in inoculated apes. 



The phenomena following the inoculation of spirochaetes into monkeys 

 have been investigated by Metchnikoff and by Soudake witch. The Cercopi- 

 theci are particularly susceptible to inoculation. 



During the febrile attack the spirochsetes are very numerous in the fluid part 

 of the blood. At the time of the crisis they disappear from the peripheral circula- 

 tion but are present in enormous numbers in the spleen where during the apyrexial 

 interval they are contained within the leucocytes, and masses of leucocytes contain- 

 ing spirochsetes can be found forming small microscopic abscesses. A single leucocyte 

 may contain several spirochaetes and occasionally accumulations of spirochsetes 

 arranged like the spokes of a wheel can be observed around some of the leucocytes. 

 The parasites soon disappear from the interior of the leucocytes leaving only irregular- 

 shaped granules and a little later the leucocytes resume their normal appearance. 

 Some of the phagocytes however have succumbed in the attack as can be shown by 

 the fact that their nuclei are destroyed and will not take up staining reagents. The 

 spirochsetes are taken up by the leucocytes while the former are living so that if a 

 little material from the spleen of an animal killed during the apyrexial interval, 

 when all the parasites are intra- cellular, be inoculated into a normal animal the 

 latter will become infected ; from which it is obvious that some of the Spirochsetes 

 retain their virulence even after being phagocyted, and it is these which in some 

 way not yet understood are responsible for the relapses occurring in the human 

 disease (Metchnikoff, Bardach). 



Some experiments of Soudakewitch are important as showing the role of the spleen 

 in relapsing fever. The spleens of a number of monkeys were removed and the 

 animals afterwards inoculated with infected material with the result that all the 

 animals died, phagocytosis was absent and the numbers of the spirochsetes went 

 on increasing until finally they exceeded in number the red cells of the blood. 



Mice and white rats can be infected by the inoculation of blood containing 

 the Spirochceta recurrentis. After intra-peritoneal inoculation the mouse 

 suffers from a typical attack of the disease with two or three relapses and 

 ultimately recovers. The rat does not as a rule suffer from relapses though 

 sometimes a single somewhat delayed relapse may be observed (Breinl and 

 Kinghorn) and has recovered its normal health in about 40 hours. Fiille- 

 born and Mayer, Uhlenhuth and Handel have not been able to infect mice and 

 rats with human blood but only with blood from an infected Cercopithecus. 



Rabbits and guinea-pigs are almost immune. 



II. West African relapsing fever (Tick fever). The spirochsete of West 

 African relapsing fever, S. duttoni, is generally speaking more virulent for 

 the lower animals than is Spirochceta, recurrentis (Breinl and Kinghorn). The 

 Cercopitheci and Macacus monkeys are very susceptible. Mice and rats 

 often die after being inoculated intra-peritoneally with infected human blood ; 

 they suffer from a number of successive attacks, usually less and less severe, 

 over a period which varies from 3-45 days. The chief lesion is an hyper- 

 trophy of the spleen with haemorrhages into the organ. 



Rabbits also suffer from a severe attack of the fever if inoculated intra- 

 peritoneally with a large dose (5 c.c. or more) of infected blood. 

 Guinea-pigs seem to be more highly immune than rabbits. 



Experimental inoculation with filtered blood. Novy and Knapp found that 

 porcelain-filtered blood from rats infected with S. recurrentis in which on 



