CHAPTER X. 

 PROTOZOA IN DISEASE. 



Certain low forms of animal life are causative of such diseases as 

 malaria and sleeping sickness. These organisms resemble each other in 

 that they are minute, of simple structure (single celled) and in that they 

 show active motion due to the presence of flagellse or cilia or due to cell 

 undulations. They are found in stagnant water containing decaying vege- 

 table and animal matter and in decaying organic matter. Most of them 

 are non-pathogenic and all are quite readily killed by means of heat and the 

 common chemical disinfectants. They do not occur in pure, fresh well, 

 spring, or hydrant water. If present it is a sure sign of vegetable contamina- 

 tion. AU liquids intended for internal use, showing the presence of amceba, 

 infusoria and other protozoa should be tested bacteriologically for the 

 presence of colon bacUli, the typhoid bacUlus and other possible pathogenic 

 organisms, animal as well as vegetable. 



The following are the more important species of protozoa and the prin- 

 cipal activities in which they are concerned: 



I. Rhizopoda. — These move by throwing out slender protoplasmic pro- 

 jections. SUicious coverings may be present. 



1. Entamosba coli. — Inhabits the large intestine. Probably harmless. 

 May be confused with phagodytes. 



2. Entamoeba histolytica. — Causes entero-colitis and dysenteric ulcera- 

 tions. It is also found in abscesses of the liver. Occurs in tropical 

 countries, less common in temperate zones. 



3. Entamceba buccalis. — Found in dental caries. Probably not patho- 

 genic. 



4. Entamoeba undulans. — Occurs in the intestinal tract. 



5. Leydenia gemmipara. — Identity doubtful. Supposed to have a 

 causal relationship to carcinomatosis (cancer). 



II. Flagellata. — Motion due to flagellse. Some possess an undulatory 

 motion; Have been classed as bacteria (SpiriUae). 



I. SpirochcBta recurrentis {Spirillum obermeieri). — This is the organism 

 which causes relapsing fever. The disease is so designated because 

 after apparent complete recovery, one or more relapses invariably 

 follow. It is not a very fatal disease (4 per cent, of deaths) and is, so far, 

 rare in the United States. It is and has been very prevalent in parts of 

 Europe. The disease can be transmitted, by inoculation, to man, 



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