DISEASES CAUSED BY PROTOZOA. 117 



threads with 4 to 10 spirals and I flagellum which 

 propels them about actively. They can be found in 

 the blood of those sick with the fever. At present the 

 infection is most widespread in India and Africa, but 

 sixty to seventy years ago epidemics occurred in this 

 country. 



People infected with the spirochetes develop a 

 fever of relapsing type. First there is a period of 

 fever lasting five to seven days, then a period of re- 

 mission of the same -duration. It is spread by insects 

 or ticks which become infected by sucking the blood 

 of patients having the disease. One attack usually 

 confers immunity. 



In preventing the spread of the disease it is im- 

 portant to isolate the patient and disinfect the bedding, 

 clothing, and apartments. Particular attention should 

 be given to the extermination of bedbugs. 



VINCENT'S ANGINA. 



This is an infectious disease of the gums, mouth, 

 or throat, characterized either by the formation of a 

 membrane which may be identical with the diphtheritic 

 membrane, or by ulcerations which have a punched- 

 out appearance. In smears made from the membrane 

 or ulcers, large, fusiform bacilli, broad in the middle, 

 with tapering ends and long spirilla, are constantly 

 found and are supposed to be the cause of the infection. 

 It is the belief now that the spirilla are but a later 

 stage in the development of the fusiform bacilli. As 



