DISEASES CAUSED BY BACTERIA 301 



Prevention of Typhoid Fever. The disease is practically over- 

 come by inoculation with dead bacteria. The way of preventing 

 typhoid fever is somewhat different from that of smallpox, for 

 which living weakened organisms are introduced into the system 

 through vaccination. Typhoid fever bacteria are developed in a 

 bouillon culture by adding live bacteria to the bouillon. After they 

 have sufficiently developed they are killed by heating the culture 

 to 140 F. for an hour. The solution must not be overheated. 



The preventive treatment is divided into three injections: 



1. An injection of 500,000,000 bacteria in a cubic centimeter of 

 about one teaspoonful salt water solution (made by adding a tea- 

 spoonful of salt to a pint of water). This treatment is given about the 

 middle part of the afternoon because reactions from the treatment, 

 if any, appear about bedtime. Rarely, nausea, vomiting, headaches, 

 and a rise in temperature develop. As a rule there is only a slight 

 headache, a feeling of drowsiness, and a tender area around the point 

 .of inoculation. All these symptoms are gone by morning, and the 

 patient is as healthy as usual. 



2. A dose of 1,000,000,000 bacteria in one cubic centimeter of 

 salt water solution is given ten 'days later. 



3. Twenty days later another dose of the same number of ba- 

 cilli is injected. . Usually no discomfort is felt from these last injec- 

 tions. 



Immunity from typhoid fever produced by the inoculation of 

 the dead bacteria lasts about two years. Since this method of com- 

 bating the disease has been used in the army, typhoid fever has 

 practically disappeared there. 



The Fly. The common house fly has received the name of 

 typhoid fly because it is the means by which the typhoid germ may 

 travel from infected material to foods which people are about to 

 eat. This fly has been known to carry 6,600,000 germs on it at one 

 time. A fly which carries only 1000 germs may be considered 

 clean. 



Flies breed in filthy places. One fly has been known to lay one 

 hundred and twenty (120) eggs in fourteen hours. It takes ten or 

 twelve days for an egg to develop. This means that a dozen genera- 

 tions can be produced in a single season. During one season one 



