PROTOZOA IN DISEASE. 157 



monkeys, mice and rats. An immunity treatment has been attempted 

 with some success. Most authorities class the organism as a fungus 

 (Spirillum). 



2. Spirochceta duttoni. This organism is the primary cause of the 

 South African tick fever (Tete fever), so-called because the carrier is a 

 species of cattle tick (Ornithodoras moubata). 



3. Spirochceta novyi. Said to be the cause of American relapsing fever. 



4. Spiroch&ta mncenti. Pathogenic; causes throat inflammation (Vin- 

 cent's angina). 



5. Treponema pallidum. The specific cause of syphilis. Often other 

 related organisms are found associated with it. This organism stains 

 with difficulty. 



6. Trypanosoma gambiense. This is the cause of the dread sleeping 

 sickness of Africa. The transmitter of the infection is the tsetse fly 



FIG. 74. A, Spirocheta refringens; b, Spirocheta pallida. The cause of syphilis. 



(Glossina palpalis). Investigations have shown that the eradication 

 of the tsetse fly would also eradicate the disease (Koch), which has 

 practically depopulated large districts in Africa. Related organisms 

 cause diseases in horses (surra, dourine and mal de caderas). There 

 are also many trypanosomes of frogs, fish and birds, but these are 

 probably harmless to man. 



Species of Leishmania cause sores and ulcers (in tropical countries). 

 Certain tropical Lamblia and Trichomonas species may cause intestinal and 

 other disturbances. 



The infusoria proper (Ciliata), while exceedingly abundant and widely 

 disseminated, are mostly non-pathogenic. The Balantidium coli is a com- 

 mon hog parasite which may also cause serious dysentery in man. 

 III. SPOROZOA. Commonly designated as amoebae. Have no cilia, move 

 by plasmic contraction of the cell and reproduce by spores. Of this group, 

 the most important species is the Plasmodium malaria which is the primary 



