FOUNDATIONS OF MODERN TROPICAL MEDICINE 



pheles, and thus made not merely a great discovery, but one which 

 ought to be in time of lasting benefit to mankind. The full develop- 

 ment of the human parasite was found out by Grassi, who also 

 showed that only Anopheles are capable of transmitting the para- 

 site. Ross and Grassi's most important discoveries have been 

 verified and extended by many people — e.g., Marchiafava, Celli, 

 Bignami, Dionisi, Daniels, Stephens, and Christophers, etc. — but 

 the account of their work will be given later. Thus, out of the fevers 

 all classed as malaria there issued a type clearly defined, to which 

 the term ' malaria ' must be restricted. 



In 1 90 1 Forde and Dutton discovered a trypanosome, called by 

 Button Trypanosoma gambiense, in a case of a peculiar irregular 

 fever in the Gambia. In 1902 Dutton and Todd observed this 

 organism in several other cases presenting the same type of fever, 

 which became known at the time as trypanosome fever, Gambia 

 fever, or Button's disease (Laveran and Mesnil). In 1902 and 1903 

 Castellani found a trypanosome in the cerebro-spinal fluid of cases 

 of sleeping sickness, and first associated it with the aetiology. 

 Further investigation by Bruce, Nabarro, and numerous observers 

 in various regions of Africa confirmed and greatly extended this 

 work. In 1903 Sambon and Brumpt independently promulgated 

 the hypothesis that the human trypanosome was carried by a 

 tsetse-fly, in all probability the Glossina palpalis ; and Bruce and 

 Nabarro experimentally proved that the Trypanosoma castellanii 

 is in reality introduced into human beings by the bite of Glossina 

 palpalis. Bruce and others considered the transmission as purely 

 mechanical, but the researches of Kleine show that the parasite 

 undergoes true development in the body of the tsetse-fly. In 1903 

 Castellani stated that man in analogy with the lower animals 

 might be infected by several species of trypanosomes. In 1909 

 Chagas discovered a form of human trypanosomiasis in South 

 America, and showed that the trypanosome causing it (5. cruzi 

 Chagas, 1909) was carried by a Conorhinus. In 1910 Stephens and 

 Fantham created a new species (T. rhodesiense), which Kinghorn and 

 Yorke in 1912 showed to be transmitted by Glossina morsitans 

 (Westwood). 



Trypanosomes were found in the lower animals long before they were 

 discovered in man. Gruby first used (1844) the term ' trypanosoma ' for a 

 flagellate he had found in the blood of frogs in 1842. A similar parasite had 

 been found by Valentin in 1841 in the common trout {Salmo fario). Very 

 little progress was made in the investigations of these organisms until 1878, 

 when Lewis, in India, described a trypanosome in the blood of rats, which was 

 named by S. Kent Trypanosoma lewisi. In 1880 Evans discovered a trypano- 

 some in animals affected with surra — Trypanosoma evansi (Steel, 1885). 

 This was a most important discovery, as it showed ti at trypano;- omes Mere 

 capable of producing disease, while previously it had been believed that these 

 parasites were harmless. In 1894 Bruce discovered the Nagana trypano- 

 some, Trypanosoma hrucei (Plimmer and Bradford, 1899), and experimentally 

 proved that the organism was conveyed by a species of tsetse-fly {Glossina 

 morsitans). Rouget in the same year observed a trypanosome in the blood 

 of horses affected with dourine — Trypanosoma equiperdum (Doflein, 1901). 



