128 TROPICAL MEDICINE AND HYGIENE 



Leiper, in addition to showing that the larvae did not 

 escape from the cyclops under natural conditions, showed 

 that if these infected cyclops were placed in water con- 

 taining hydrochloric acid to the extent of 0*2 per cent., the 

 equivalent of the acidity of the gastric juice during healthy 

 digestion, the cyclops became motionless and died, whilst 

 the Guinea-worm larvae became active and escaped from 

 the body of the cyclops. This pointed to infection taking 

 place by the infected cyclops being swallowed and the 

 embryos stimulated in this way becoming active, and 

 then passing from the stomach into the tissues. He fed 

 a monkey on cyclops infected five weeks previously, and 

 in this monkey, which died six months later in England, 

 three immature females, which closely resembled in all 

 essentials the Dracunculus (Filarid) medinensis, and two 

 males were found. As from numerous observations it is 

 known that nearly a year elapses before Guinea-worms 

 mature in man, these immature worms must have been 

 derived from the cyclops. 



The course of events is therefore clear. The embryos 

 are discharged by the parental forms in the water in 

 which men bathe. The cyclops in this water serve as 

 intermediate hosts, and these cyclops about five weeks 

 later contain mature larvae. If swallowed by man they 

 are set free in the stomach, and in the course of a year 

 make their appearance as adult fertilized females, full of 

 embryos, beneath the cuticle, which they perforate. They 

 can then discharge the embryos into the water in which 

 man bathes, and infect a fresh generation of cyclops. 



Prophylaxis. There are three measures which may be 

 considered: (i) Destruction of cyclops. (2) Prevention 

 of the infection of the intermediate host cyclops by 

 prevention of persons with Guinea-worm bathing in water 

 containing these cyclops. (3) Prevention of infection of 

 man by infected cyclops. The last is the most practical 

 method. It involves drinking only water in which 

 bathing has not been, permitted, or the boiling of such 

 water before use. 



