SURVIVAL OF PATHOGENS IN SOIL AND WATER 27 



DESTRUCTION OF INJURIOUS MICRO- 

 ORGANISMS 



Improper methods of disposal of human and animal wastes were 

 responsible, in the early history of mankind, for many epidemics of 

 cholera, typhoid, plague, and other diseases. Only in recent years, after 

 man learned the nature of the spread of these diseases, were proper 

 methods developed for disposing of human wastes. According to Win- 

 field (990), fecal-borne diseases rank with venereal disease and tuber- 

 culosis as the most important infectious diseases of China, because the 

 people do not maintain proper sanitation and because human excreta are 

 used as fertilizers. Any successful system for the control of these dis- 

 eases must be sanitary and at the same time profitable. The composting 

 method can meet these requirements. 



To illustrate this point, it is sufficient to consider an analysis (990) 

 of the occurrence of Ascaris lumbricoides, its transmission, and its rela- 

 tion to Entamoeba histolytica. Of 1,190 persons examined, 81 per cent 

 were positive for ascaris, with an average egg count of 14,000 per cubic 

 centimeter. Children had a higher count than adults, and females a 

 higher count than males. The life habits of the Chinese people are 

 highly favorable for the spread of ascaris. By a special process of com- 

 posting of feces, sufficient heat was produced to destroy disease-produc- 

 ing organisms and their reproductive bodies. The compost thus pro- 

 duced is highly effective as a fertilizer. 



Many other natural substrates, like saliva (704), possess antibacterial 

 properties due to the antagonistic action of their own bacterial popula- 

 tions. Though antagonistic microorganisms may persist in soil or in 

 other natural substrates, substances toxic to bacteria soon tend to be 

 destroyed (444). 



SURVIVAL OF HUMAN AND ANIMAL PATHOGENS 

 IN SOIL AND WATER 



During the period 1878 to 1890 following the brilliant work of 

 Pasteur, when bacteriology was still in its infancy, medical bacteriolo- 

 gists took much interest in soil microbes. This was due largely to the 

 belief that causative agents of disease that find their way into the soil 



