MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS QOI 



Several spirochaetes are parasitic in man. Spirochceta dentium and Spiro- 

 clmta buccalis are harmless organisms which are found in tartar, about the 

 teeth. 



Spirochata -vincenti occurs in great numbers in a certain form of sore throat. 

 Other spirochaetes have been found in foul ulcers, and others have been found in 

 association with bronchitis, urethritis and enteritis. All these are comparatively 

 unimportant parasites. Spitochata recurrentis, the cause of relapsing fever, is the 

 most important of them. 



RELAPSING FEVER 

 Spirochceta recurrentis Lebert, 1874 



The relapsing fevers may occur in any part of the world. They 

 are caused by spirochaetes and are transmitted by ticks and lice. 



FIG. 192. Ornithodoros moubata. (Murray from Doflein.) 



The disease is carried by Ornothodoros moubata (Fig. 192) in Africa 

 and wherever this tick exists. It is similarly carried in Persia and else- 

 where by Argas persicus. Other ticks carry it in Mexico and in South 

 America. In Europe, Asia and Northern Africa, the disease is usually 

 transmitted by lice. There are grounds for believing that it may also 

 be carried by other biting ectoparasites such as bedbugs. 



The spirochaetes causing relapsing fevers in man are sometimes 

 described as belonging to different species mainly because experimental 

 animals immune to infection by one of the spirochaetes are susceptible 

 to infection by another. This difference is not of specific importance 

 since two strains can be developed from a single spirochaete neither of 

 which affords immunity against infection by the other. Because of 



