Weird Diseases of Africa 



THE STORY OF STRANGE PARASITES WHICH TRAVEL FROM MAN TO 



MAN THROUGH THE AGENCY OF TSETSE FLY. MOSQUITO. 



OR OTHER ^'INTERMEDIATE HOST" 



By WALTER B. JAMES 



President of the New York Academy of Medicine 



FEOM earliest times the '"Dark Con- 

 tinent" has been known as tlie 

 home of peculiar men and beasts. 

 Modern science, especially medical sci- 

 ence, now teaches us that the minute, 

 even microscopic, life of Africa is no 

 less individual and remarkable, espe- 

 cially its parasitic life, while the symp- 

 toms these parasites produce in the 

 unfortunate human beings infested by 

 them are equally weird and generally 

 extraordinarily unpleasant. Many of 

 the diseases produced by these micro- 

 scopic parasites have been known to 

 physicians— at least as far as their 

 symptoms were concerned — for many 

 years, but only lately have the wider 

 settlement of Africa and the progress 

 of medical science, with the establish- 

 ment of schools of tropical medicine 

 like those at Liverpool and Harvard 

 University, made the nature of these 

 important diseases clear to us. 



In the slavery days in America it 

 was noticed that often in a shipload of 

 slaves who had been captured in the 

 interior of Africa and sent here, a large 

 number would sicken in a peculiar way 

 and then die. They first became dull 

 and listless, then so drowsy that they 

 could be roused only with great diffi- 

 culty. They refused to eat and then 

 died. Other and subtler symptoms were 

 overlooked. It was natural that illness 

 and death should be ascribed to home- 

 sickness. These people, we now real- 

 ize, had the "sleeping sickness." In 

 their jungle homes they had been bitten 

 by the tsetse flies that had previously 

 bitten persons, or perhaps animals, hav- 

 ing this disease, and had conveyed the 

 parasite in this way. For the germ — 

 a worm, not a bacterium — inhabits the 

 blood of its victim, and multiplies 

 there. ^ 



When the blood containing them is 



taken into the stomach of the fly, the 

 germs multiply there (the fly acting 

 as the intermediate host between the 

 two human beings) and go through a 

 phase in their lives that may be likened 

 — to use a comparison familiar to us 

 all — to one of the stages in the life of 

 a butterfly. The progeny find their way 

 to the salivary glands of the fly and lie 

 there, ready to be injected into the 

 blood of the next person to whom the 

 tsetse turns for a meal. If we take a 

 drop of blood from the finger of a per- 

 son who is in the advanced stage of 

 sleeping sickness, and put it under a 

 powerful microscope, a remarkal)le situ- 

 ation is evident. Enormous numbers 

 of the parasites (trypanosomes) are 

 seen rushing about, apparently aim- 

 lessly, knocking the blood corpuscles 

 about like so many ninepins, and one 

 wonders that a man could live at all 

 with such weird things going on in his 

 blood. 



Whole tribes of blacks in Africa have 

 been annihilated by this disease and, as 

 one of the methods of controlling it, it 

 has been suggested that in the parts of 

 Africa most afl'ected, the wild game 

 should be killed off, for it has been 

 shown that animals, too, may be hosts 

 for such parasites and thus help to pre- 

 serve them. The laws that secure the 

 perpetuation of these minute enemies 

 of man are just as effective as the corre- 

 sponding laws that seem to us to work 

 for our benefit. Nature is impartial. 

 To be sure she has given us an inteili- 



' This parasite is the Trypanosoma gambiense , 

 and is generally called the trypanosome of sleeping 

 sickness. Such a parasite generally has to live in 

 two different kinds of animals in order to round 

 out its complete life, and for each variety of para- 

 site the two hosts are always the same. One is 

 called the "intermediate host," the other, the "final 

 host." In the case of the trypanosome of sleeping 

 sickness, the tsetse fly is the intermediate host, 

 man (or in some cases the antelope) the final host. 



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