610 PATHOGENIC MICROORGANISMS 



spirochsete found in the African disease is usually spoken of at present 

 as "Spirochseta Duttoni." Novy and Knapp, 1 after extensive studies 

 with the microorganisms from various sources, have come to the conclu- 

 sion that, although closely related, definite species differences exist be- 

 tween the two types mentioned above, and that these again are definitely 

 distinguished from similar organisms described by Turnbull 2 as occurring 

 in a similar disease observed in India. 



The mode of transmission of this disease is not clear for all types. 

 Dutton and Todd, however, were able to show satisfactorily that, in the 

 case of the African disease at least, transmission occurs through the 

 intermediation of a species of tick. The conditions under which such 

 intermediation occurs have been carefully studied by Koch. 3 The 

 tick (Ornithodorus moubata) infects itself when sucking blood from 

 an infected human being. The spirochsete may remain alive and 

 demonstrable within the body of the tick for as long as three days. 

 Koch has shown, furthernore, that they may be found also within the 

 eggs laid by an infected female tick. He succeeded in producing experi- 

 mental infection in monkeys by subjecting the animals to the bites 

 of the infected insects. For the European variety of the disease no 

 such intermediate host has as yet been demonstrated. 



Immunity. It has long been a well-known fact that recovery from 

 an attack of relapsing fever usually results in a more or less definite 

 immunity. The blood of human beings, monkeys, and rats which have 

 recovered from an attack of this disease show definite and specific 

 bactericidal and agglutinating substances, and Novy and Knapp have 

 demonstrated that the blood serum of such animals may be used to 

 Confer passive immunity upon others. 



VINCENT'S ANGINA 



The condition known as Vincent's angina consists of an inflamma- 

 tory lesion in the mouth, pharynx, or throat, situated most frequently 

 upon the tonsils. The disease usually begins as an acute stomatitis, 

 pharyngitis, or tonsillitis, which soon leads to the formation of a pseudo- 

 membrane, which, at this stage, has a great deal of resemblance to that 

 caused by the diphtheria bacillus. At later stages of the disease there 

 may be distinct ulceration, the ulcers having a well-defined margin 



1 Novy and Knapp, loc. cit. 2 Turnbull, Indian Med. Gaz., 1905. 



3 Koch, Berl. med. Woch., 1906. 



