PUBLIC HEALTH 237 



cannot emphasize these points better than by studying the his- 

 tory of a typical typhoid epidemic, taking as our illustration 

 the well-known outbreak in 1885, in Plymouth, Pennsylvania, 

 a town of about eighty-five hundred inhabitants. Typhoid fever 

 appeared in the spring with such violence that from fifty to 

 two hundred cases developed daily, until about eleven hundred 

 persons were stricken (about one eighth of the population), 

 more than one hundred of whom died. The disease appeared 

 only in persons who drank the hydrant water from certain 

 town reservoirs, and those who used private wells escaped. On 

 investigation the following facts were established. During the 

 winter a case of typhoid fever, contracted in Philadelphia, had 

 been cared for in a house which stood close to a stream that 

 flowed into the town reservoirs. During the illness intestinal 

 discharges from the patient had been thrown out upon the 

 snow within a few feet of this stream. During late March and 

 early April the snow melted and there were frequent rains that 

 washed the germ-laden material into the stream, which carried 

 it into the reservoirs. The first cases of typhoid fever in the 



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epidemic appeared within two or three weeks (the period of 

 incubation in typhoid fever) after the infected water had been 

 distributed through the town. Thus the entire epidemic was 

 due to the carelessness or ignorance of attendants who did not 

 safely dispose of the germ-filled wastes from a typhoid patient. 

 The terrible outbreaks of cholera are usually due to infection 



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of water supplies. The germs of tuberculosis are very widely 

 distributed by means of the dried sputum of diseased persons, 

 hence the importance of rules against spitting in public places. 

 The common diseases incident to the association of children in 

 school, such as diphtheria, scarlet fever, measles, and mumps, 

 make necessary the strict isolation of all cases until there is no 

 possible danger of contagion. As the sources of germ infection 

 are reduced or stamped out, the possibilities of germ diseases 

 become at once lessened. The healthy human body is wonder- 



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fully resistant, and the problem of public health is largely the 



