Nov. i, 1920 Control of Fluke Diseases 207 



solution of the correct amount of the salt from a sack attached to the 

 back of a canoe or boat, or, in very small pools, to the end of a pole. 

 Dissolved copper sulphate can conveniently be sprayed on small pools 

 from a spray pump or even an ordinary garden watering pot. In most 

 cases Bullinus, Physopsis, Planorbis, and Limnaea could be destroyed by 

 these methods. 



(7) For the treatment of running streams the use of a barrel of suitable 

 size, fitted with a screened spigot, is recommended. The barrel is filled 

 with water, and sufficient copper sulphate is dissolved into it so that the 

 desired amount will be fed into the water per hour. Inasmuch as no two 

 spigots will flow at exactly the same rate and since the rate of flow will 

 diminish as the level of the fluid in the barrel is lowered, it is necessary 

 to determine beforehand the rate of flow at different levels and to cal- 

 culate the amount of copper sulphate to be dissolved according to the 

 average rate of flow. By the use of a tube of equal or greater length than 

 the height of the barrel, so that the head is increased, the diminution in 

 rate of flow can be greatly lessened. The addition of a few cubic centi- 

 meters of sulphuric acid to the solution in the barrel prevents the pre- 

 cipitation of iron sulphate, which is present as an impurity in commercial 

 copper sulphate and tends to clog the filter. Melania and Blanfordia 

 would probably have to be attacked by this method, since they live in 

 flowing water. 



(8) In water which is not alkaline, large streams could be treated 

 more easily by allowing the copper sulphate, in the form of uniform 

 crystals, to dissolve directly into the stream through the screened end of 

 a tube. The amount of salt which would go into solution per unit of 

 time would depend on the diameter of the tube, the speed of the stream, 

 and the temperature of the water. If some feasible method could be 

 devised for slightly acidifying the water at the point where solution of 

 the salt is taking place, this method could be used advantageously in all 

 but very small streams. 



(9) It is believed that by attacking the intermediate hosts of the 

 various pathogenic flukes of man and domestic animals by the use of 

 copper sulphate as herein outlined trematode diseases can successfully be 

 brought under control and can either be greatly reduced or entirely 

 eliminated in endemic areas, and this with comparatively little expense 

 and without active cooperation on the part of natives. With Govern- 

 ment aid and supervision, the work being carried out under the direction 

 of scientifically trained men or commissions, it seems entirely possible 

 that entire States or countries, at least in the vicinity of towns and 

 villages, could be freed of human fluke diseases, and that seriously 

 affected districts where sheep and cattle are raised could have the fluke 

 scourge wiped out in a short time with little expense. 



