MICROOROANISMS AND HUMAN WELFARE 37 



typhoid patients or those who have become typhoid car- 

 riers." 1 It has been proved over and over again that the 

 common house fly is frequently the means by which typhoid 

 fever is transmitted (A. B., 43), since these insects often 

 alight on the excretions of typhoid patients, and then carry 

 the germs on their hairy feet (A. B., Fig. 40), and so infect 

 the foods on which they aUght. 



34. Prevention of typhoid fever. — It is evident, then, 

 that if the excretions from the intestines and kidneys of 

 typhoid patients were thoroughly disinfected by carbolic 

 acid or other germicides,' the spread of typhoid fever would 

 be very largely prevented. It must be borne in mind, 

 however, that the bacteria of this disease continue to live 

 in great numbers and to multiply in the intestines of some 

 people who have had typhoid fever years after recovery from 

 the disease, and these people are the so-called " typhoid 

 carriers." ^ 



One of the most difficult problems that formerly confronted armies 

 was that of preventing typhoid infection. In the Mexican War and 

 in the Civil War the armies on both sides paid frightful toU to this 

 dread disease, and even in the Cuban War, five thousand men in the 

 United States Army died of typhoid fever or other fly-borne dis- 

 eases, while only three hundred were killed by Spanish bullets. 

 Sanitary camps, however, have greatly improved the situation, and 

 in recent years an anti-typhoid vaccine, somewhat like that used in 

 the prevention of smallpox, is injected as a means of prevention, 

 and the results of the use of this vaccine have been most favorable. 

 The improvement in army health is strikingly shown by comparing 

 figures for two army divisions of about the same size, one at Jack- 

 sonville, Florida, during the Spanish- American War in 1898, the 



' Quoted from article on typhoid fever, in New International En- 

 cyclopedia, copyrighted 1903 by Dodd, Mead, and Co. 

 ' See footnote, p. 39. 



