670 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



Several spirochaetes are parasitic in man. Spirochata dentium (Fig. 118) and 

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

 teeth. 



Spirochata mncenti sometimes causes a dangerous form of sore throat 

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

 bronchitis and enteritis. All these are comparatively unimportant parasites: 

 Spirochceta duttoni, Spirochceta obermeieri and Spirochceta pallidula are more im- 

 portant ones. 



FIG. 118. Spirochceta dentium in pure culture. (After Milhlens from Doftein.) 



AFRICAN TICK FEVER. 

 Spirochceta duttoni. 



African tick fever is a disease caused by Spirochceta duttoni and trans- 

 mitted by the bites of a tick Ornithodoros moubata (Fig. 120). 



This disease exists in Central and Eastern Africa, wherever Ornith- 

 odoros moubata (Fig. 119) occurs. A disease, which is probably caused 

 by a spirochaete, is transmitted by another tick, Argas persicus, in Persia. 



