FOUNDATIONS OF MODERN TROPICAL MEDICINE 



patient by clinical methods, as to commit the error of entirely 

 trusting to the microscopical diagnosis. If he trusts entirely to 

 the clinical diagnosis errors must occur ; if he leans absolutely upon 

 laboratory examinations, which are often negative, he will again 

 find himself in difficulties. The real foundation of modern tropical 

 medicine is the blending together of clinical work with scientific 

 research, thus making a living progressive science of medicine, in 

 which causation, treatment, and prophylaxis of known diseases are 

 associated with State-aided research into the unknown. We will 

 now briefly look at the history of these various points. 



Causation of Diseases. — One of the most marked features of 

 modern tropical medicine is the success which has attended attempts 

 to find the causal agent of the various diseases; and to trace the 

 rather romantic history of these discoveries, it is necessary to sub- 

 divide the subject into Helminthology, Protozoology, Mycology, 

 Bacteriology, Serums and Vaccines, Entomology, Toxicology, 

 Climatology, and Dietetics. 



Helminthology. — We have already noted that the Ebers Papyrus 

 mentioned the presence of worms in the intestines ; that Moses not 

 merely knew the guinea-worm, but how to extract it by winding it 

 round a stick; and we have further drawn attention to Agath- 

 archides' description of this worm in 170 B.C., and to the reference 

 to broad and round worms by Paul of i^^gina ; and may, therefore, 

 pass on to more recent work. 



Trematodjes were first recognized by Jehan de Brie in the form of the liver 

 fluke of sheep, which was afterwards described in 1547 by Gabucinez. This 

 initial work was extended later by Leeuwenhoek (1675), Swammerdam (1752), 

 Roienhof (1758), Mliller (1777), Zeder (1800), wliocalled them ' sucking worms,' 

 and Rudolphi (1808), who gave the name Trematode, from Tprj/maTwdrjs, 

 meaning pierced by holes. Quite recently these worms have been the subject 

 of two great discoveries, which may be briefly summarized. 



In 1874 the trematode Clonorchis sinensis { — C. endemicus) was discovered 

 by McConnell in the liver of a Chinaman, but the method of infection was not 

 known until Kobayashi worked this out in 1912, 1915, and 1917, showing 

 that the encysted stage could be found in twelve varieties of fish, and that 

 kittens produced the adult trematode when fed upon infected fish, and finally 

 that the first intermediate host is a mollusc — i.e., a species of Melania. 



In 1 85 1 Bilharz discovered the trematode Schistosoma hcsmatobium in the 

 portal vein of an Egyptian. Since 1907 Sambon has shown that under this 

 name was concealed, as suggested by Manson, a second parasite, which he 

 called Schistosoma mansoni. In 1915 Leiper not merely confirmed the 

 existence of these two distinct parasites, but traced their life-histories through 

 the molluscs to the adult form in mammals. This is indeed a great and 

 valuable discovery, and by no means the first by which this distinguished 

 helminthologist has benefited mankind. 



With regard to the Cestoda and Nemathelminthes space does not permit of 

 a history at this point, as this will be given later; but with regard to the latter 

 group Sir Patrick Hanson's researches into filariasis were epoch-making. 



The detailed history of Filaria bancrofti will be given later, and it will 

 suffice to state here that the microfilaria was discovered by Demarquay in 

 1863, and that Manson discovered its development in the mosquito in the 

 years 1 877-1 879, while in 1882 he laid stress upon the nocturnal periodicity 

 of the microfilaria, a fact entirely disbelieved when first reported. 



The great importance of the discovery of the development of this worm in a 



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