264 



BACTERIA AND DISEASE 



,/V 



son to another by kissing, by putting into the mouth objects which 

 have come in contact with the mouth of the patient, or by food 

 which contains the germs, and particularly through the droplets 

 or spray which comes from the mouth of the person having the 

 disease. 



Other Diseases spread through Mouth Spray. — Influenza, 

 pneumonia, whooping cough, and certain kinds of colds, and many 



of the so-called children's dis- 

 eases, are caused by bacteria 

 or other microscopic organ- 

 isms. Nearly all are spread 

 by direct contact with persons 

 having the disease, and the con- 

 tact in most cases is brought 

 about by the ^'droplet method" 

 of infection . In our army dur- 

 ing the World War, influenza, 

 coupled with pneumonia, was 

 responsible for fourteen times 

 as many deaths as were caused 



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hydc Pdrk Dorchester 



mton 



This figure shows how a milk route might 

 spread diphtheria. X is a farm on which 

 occurred a case of diphtheria that was re- 

 sponsible for all the cases along milk routes 

 A and F in Hyde Park, Dorchester, and 

 Milton. How would you explain this ? 



by shells and poison gases. This disease is periodically epidemic, 

 the last bad outbreak previous to this being in 1889. Influenza is 

 apparently spread largely by human carriers, or people who have 

 a slight attack but are capable of passing the disease on in its most 

 serious form. 



Typhoid Fever. — Typhoid fever, not many years ago, was one 

 of the most common germ diseases in this country and Europe. 

 But knowledge of the cause and prevention has greatly decreased 

 its death rate in recent years. Typhoid germs live in the intestine 

 and from there get into the blood and are carried to all parts of the 

 body. The products which they make cause the fever so charac- 

 teristic of the disease. The germs multiply very rapidly in the 

 intestine and are passed off from the body with the excreta from 

 the food tube. If these germs get into the water supply of a town, 

 an epidemic of t3q)hoid will result. In one such epidemic there 

 were 5000 cases of typhoid in a city of only 30,000 inhabitants. 

 Chicago and other cities which obtained their drinking water 

 from lakes polluted with sewage always had a high death rate from 



