WEIRD DISEASES OF AFRICA 



321 



When the parent worms have se- 

 lected a large lymph vessel at the base 

 of a leg or an arm, for instance, and 

 have started in raising a large family, 

 we find that in entire disregard of the 

 comfort of their host, they have soon 

 completely blocked up the vessel, and 

 so produced a slow chronic congestion 

 of the whole limb below. The limb 

 then becomes of enormous size, and 

 from its supposed likeness to the shape- 

 less leg of an elephant, the disease is 

 now called "elephantiasis." When we 

 travel in the tropics, especially in 

 Africa, and see — as one often does — a 

 person with enormous enlargement of 

 one arm and hand or one leg and foot, 

 we may be quite sure that it is a ease 

 of iilariasis, and that there is a colony, 

 as above described, living in the armpit 

 or groin. These cases occur also in 

 other countries, indeed in almost every 

 tropical and subtropical land into 

 which the disease is introduced through 

 travel. It, like malaria, is to be pre- 

 vented only by getting rid of mosqui- 

 toes, the intermediate host. 



There is another species of filaria, 

 the Filaria loa, very common in Africa, 

 which is transmitted to man by the 

 mangrove fly, a common blood-sucking 

 insect in that country. This worm set- 

 tles in some of the tissues just beneath 

 the skin, often in the lower eyelids, 

 where it produces uncomfortable swell- 

 ings. 



Another peculiar African parasite is 

 the guinea worm. This, too, has an 

 interesting life history. Little or noth- 

 ing is known of the male worm, but the 

 female, very slender in diameter al- 

 though attaining a length of three or 

 four feet in adult life, is found imme- 

 diately beneath the skin usually of the 

 lower limbs. It has probably been fer- 

 tilized before entering, and, lying im- 

 mediately under the skin of its host, 

 when fully grown it pierces this skin 

 and through the minute aperture ex- 

 trudes countless minute young or larvae, 

 in successive crops. 



By this time it has caused much irri- 

 tation and suffering and perhaps dis- 

 ability to the host. The larvae find 

 their way into the water as the natives 

 walk through streams and puddles. In 



the water they are taken up by a 

 minute aquatic creature called Cyclops, 

 which becomes the intermediate host, 

 and within its body they go through one 

 of their life phases. 



The Cyclops later is taken into the 

 human being's stomach in the drinking 

 water, where it perishes and its minute 

 body is dissolved in the gastric juice. 

 This sets free in the native's stomach 

 the contained living larvae, one or more 

 of which may then succeed in boring 

 through the stomach wall into the body 

 tissues. Now an imperative instinct 

 urges the developing worm to find its 

 way through the body toward the skin 

 in order that it may place its numerous 

 young on the surface, as in this way 

 only can they find the Cyclops, neces- 

 sary to the completion of their life 

 cycle. For this reason, too, apparently, 

 the female worm seeks the native's 

 lower limbs, for these come most in eon- 

 tact with puddles of water, and it is in 

 puddle water that the Cyclops espe- 

 cially abounds. In India, water car- 

 riers bearing skins of water on their 

 backs are subject to guinea worm of the 

 skin of the back, for in them the para- 

 site's instinct leads it to seek this part 

 of the body. 



In all of these organisms and their 

 behavior we see Nature's wonderful 

 methods for the continuation of life of 

 even the lowest species. Design, and 

 successful design, is just as surely seen 

 in the lives of the trypanosomes, the 

 filarife, and the guinea worm as in 

 the wonderful strength of the elephant, 

 the tough hide of the rhinoceros, or the 

 fleetness of the antelope and the ostrich. 

 We realize that we are not Nature's 

 chosen children but must take our 

 chances with the rest of life; that Na- 

 ture cares just as much for the para- 

 sites that plague us as she does for us 

 who are plagued by them ; that she 

 looks to us to take care of ourselves 

 with the weapons she has put into our 

 hands or else perish and make way for 

 others Avho use her gifts to better pur- 

 pose. It l)ehooves us, therefore, to use 

 our intellects, our only real weapon in 

 the fight against disease, and to turn 

 for aid to science, which offers us the 

 only hope of victory. 



