8 IxXTRODUCTlOX 



Yellow Fever Commission in 1900, and to dengue by Graham 

 in 1902; the relation of ticks to African relapsing fever by Dutton 

 and Todd, and independently by Koch, in 1905; the relation 

 of ticks to spotted fever by Ricketts in 1906; the relation of 

 lice to typhus by XicoUe and his fellow workers in Algeria in 1909, 

 and independently bj'- Ricketts and Wilder and by Anderson and 

 Goldberger in Mexico in the same year (publivshed in 1910); 

 the relation of cone-noses to a South American trypanosome 

 disease by Chagas in 1909; the life history of blood flukes by 

 Leiper in 1914 and 1915; and the role of crabs as second inter- 

 mediate hosts of lung flukes by Nakagawa in 1916. 



The evolution of knowledge concerning the treatment of para- 

 sitic diseases has proceeded along two distinct lines, one, de- 

 struction of the parasites by drugs which are more or less 

 specifically poisonous to them, the other by vaccination or immu- 

 nization. One of the first specific drugs known was quinine for 

 malaria. The use of cinchona bark from which quinine in its 

 various forms is manufactured is said to have originated with the 

 Indians of Ecuador, and to have been introduced into Europe 

 bj' Spaniards in 1642. The sulphate of quinine, which is the 

 form of the drug in commonest use now, was first used in 1840. 

 In 1880 Bozzolo, an Italian, first introduced th^-mol as a remedy 

 for intestinal worms, especially hookworm, and this has been 

 considered a standard and almost specific cure for hookworm 

 until within the last two years, when oil of Chenopodium has 

 been substituted for it to a large extent. The next specific drug 

 of great importance to be discovered was salvarsan for spiro- 

 chsetes, discovered bj' Ehrlich in 1905. In the same year 

 atoxyl, one of the most efficient remedies yet discovered for 

 trypanosome diseases, was discovered by Thomas. Emetin was 

 discovered to be a specific remedy for amebic dj^sentery by 

 Rogers in 1913 as the result of Vedder's work with ipecac, from 

 which emetin is manufactured. In 1914 tartar emetic, pre- 

 viously used as an alternative for arsenic compounds (chiefly 

 atoxyl) against trypanosomes, was discovered by Vianna to be 

 a wonderfully efficient specific remedy for the severe South 

 American leishmaniasis, and was subsequently found to be spe- 

 cific for all Leishmnnia diseases. 



Treatment and prevention of disease by imnmnization has 

 experienced a wonderful development in the past 35 or 40 years. 



