RBVlteW — TROPICAL MEDICINE, ETC. 



85 



flora their host by the gastric Juice, reach the cormective tissues l)y penetrating the gut wall, 

 parasite will necessarily be broken : — 



The life-cycle of the 



(1) By the death of the embryos, either from sepsis while still within the parent worm, or, if after their 

 discharge, by saltish water or drying. (2) If Cyclops arc not present in the water or, if the infected cyclops 

 die or are not taken into the human stomach. (3) If the larvae, ingested by the final host, are immature or fail to 

 escape fi-om the chitiuous sheath of the cyclops. Though they do lind their final habitat, the cycle will still be 

 incomplete if (4) there are not both males and females among the matured adults and if in their wandering the 

 females are not impregnated. 



It will at once be seen from the above summary that the isolation of infective man 

 from healthy cyclops and of infected cyclops from man must be the object of any organised 

 eli'ort to stamp out dracontiasis. 



Leiper then proceeds to detail preventive methods, so far as the West Coast of Africa is 

 concerned. These really resolve themselves into prevention of the fouling of water and the 

 provision of pure water. They have more or less a local bearing, but ho mentions that he 

 found another nematode larva in cyclops which might be a source of error in the course 

 of investigations. Finally, in a suggestive paragraph, he indicates lines of future work. We 

 tabulate the various points : — 



1. Accurate observations as regards the conditions under which the intermediate host lives and multiplies in 

 tropical countries. 



2. Determination of its natural enemies. 



3. Determination of its food supply. 



4. Oljservatious as to whether it can survive the drought of the summer, buried beneath the sun-caked mud, 

 or if, when once a pool has dried, it must be re-stocked from another source. 



5. E.xperiments to see if, by the addition of chemicals, we can destroy the cyclops in suspected waters 

 without rendering these useless or dangerous to man. 



As if in answer to these suggestions by Leiper, we find papers by Graham and Brady' on 

 the Cyclopidse of the African Gold Coast. The former points out that the inference that all 

 species of Copepoda cannot act as efficient hosts to guinea worm is strengthened by the 

 following considerations : — 



1. There is a large number of species. 



2. The habits of the different species vary greatly. Some are surface feeders, some are found at the bottom. 

 Some inhabit foul, some clean water. Some leave the water to climb on stalks of water-weed enveloped in a drop 

 of water carried with them, some do not leave the water ; some are found in streams, some are not. 



3. The different species are infested by different parasites, some only by eoto, others by ento-parasites 

 (worms). 



4. The different species differ in the date of their appearance in the pools. Some are found early in May ; 

 some appear, or, nt least, only become numerous, in July. 



The significance of the date of appearance is dealt with in a previous paper,- where it is 

 shown that, in the Gold Coast, June is the month during which the signs and symptoms 

 of guinea worm infection attain their maximum. Presumably the month of maximum 

 manifestation in man is the month of maximum infection of cyclops. It is pointed out that 

 in the locality examined, when the streams were full of water, cyclops were found in the 

 streams and not in the wells, but when the channels were dry the cyclops occurred in the 

 wells and bred there. The natives stand in the wells during the dry season whilst drawing 

 water ; the embryos in their legs can then escape and infect the cyclops. The prophylactic 

 measures recommended are (1) careful filtration of the drinking water ; a fine handkerchief 

 will serve the purpose, as by this means cyclops can be readily removed ; (2) prevention of 

 infection of cyclops by providing troughs for the natives to draw water from, so that the 

 cyclops is excluded. 



In a discussion on the above remarks, Sandwith stated that in the Sudan human beings 

 suffered from Filaria viedineiisia during two or three months of the year only, there being a 

 distinct periodicity. Chalmers stated his belief that the great amount of physical infirmity 

 due to guinea worm was not fully appreciated. 



The life-span of the female worm, as noted by Manson and others, extends to about one 

 year (Graham says roughly ten months), and evidently depends on the habits of the species 

 of cyclops which serves as its intermediate host. 



Guinea 

 Worm — 



continued 



1 Brady, Q. S. (November 9th, 1907), "Notes on Dr. Graham's Collection of Cyclopids fi'om the African Gold 

 Coast." Annah of Tropical MnUcinr mid raraaitoloyu, Series T.M., Vol. I., No. 3, p. 423. 



^ Graham, W. M. (August loth, 1905), "Guinea Worm and its Hosts." Journal of Tropical Medicine 

 p. 248, Vol. V. 



