234 Arthropods as Essential Hosts of Pathogenic Protozoa 



Other Types of Relapsing Fever of Man — In addition to the three 

 types of human relapsing fever already referred to, several others 

 have been distinguished and have been attributed to distinct species 

 of spirochetes. The various spirochastoses of man are: 



African, caused by 5. duttoni; European, caused by 5. recur- , 

 rentis; North African, caused by 5. berbera; East African, caused 

 by S. rossi; East Indian, caused by S. carteri; North American, 

 caused by S. novyi; South American, caused by 5. duttoni(?) 



Nuttall (1912) in his valuable resume of the subject, has em- 

 phasized that "in View of the morphological similarity of the sup- 

 posedly different species of spirochaetes and their individual variations 

 in virulence, we may well doubt if any of the 'species' are valid. 

 As I pointed out four years ago, the various specific names given to 

 the spirochetes causing relapsing fever in man may be used merely 

 for convenience to distinguish strains or races of different origin. 

 They cannot be regarded as valid names, in the sense of scientific 

 nomenclature, for virulence and immunity reactions are not adequate 

 tests of specificity." 



North African Relapsing Fever of Man — The type of human 

 relapsing fever to be met with in Algeria, Tunis, and Tripoli, is due to 

 a Spirochceta which does not differ morphologically from Spirochceta 

 duttoni, but which has been separated on biological grounds as 

 Spirochceta berberi. 



Experimenting with this type of disease in Algeria, Sergent and 

 Foly (19 10), twice succeeded in transmitting it from man to monkeys 

 by inoculation of crushed body lice and in two cases obtained infec- 

 tion of human subjects who had received infected lice under their 

 clothing and who slept under coverings harboring many of the lice 

 which had fed upon a patient. Their results were negative with 

 Argas persicus, Cimex lectularius, Musca domestica, Hcematopinus 

 spinulosus and Ceratophyllus fasciatus. They found body lice 

 ■ associated with every case of relapsing fever which they found in 

 Algeria. 



Nicolle, Blaizot, and Conseil (1912) showed that the louse did 

 not transmit the parasite by its bite. Two or three hours after it 

 has fed on a patient, the spirochastes begin to break up and finally 

 they disappear, so that after a day, repeated examinations fail to 

 reveal them. They persist, nevertheless, in some unknown form, 

 for if the observations are continued they reappear in eight to twelve 



