Page Fourteen 



MONTANA STATE FISH AND GAME DEPARTMENT 



VKR fluke disease or 

 what is often called by 

 hunters "rotten liver" 

 is caused by a flat ova, 

 leaf shaped, fluke-like 

 worm (fasciola hepat- 

 ica). This parasite may 

 infest any ruminant, 

 that is, any animal that chews its cud. 

 It may also occasionally infest other 

 animals and man. Sheep are the prin- 

 ciple sufferers closely followed by goats, 

 deer, elk and cattle. 



The lite cycle of this parasite is par- 

 ticularly interesting. The adult fluke 

 is found in the bile ducts and liver sub- 

 stance of the infested animal. The ma- 

 ture fluke is flat, grayish or pale 

 brown in color and approximately one 

 inch long by half an inch wide. Imma- 

 ture flukes also may be observed in the 

 liver as small as one-eighth of an inch 

 in length. The matured fluke may pro- 

 duce one hundred thousand eggs or 

 more. These eg gs pass down the bile 

 ducts into the intestines and then into 

 the outer world along with the drop- 

 pings of the infested animal. Eggs 

 which reach water hatch, those which 

 remain on dry ground do not hatch. 

 When eggs hatch they liberate a 

 minute embryo fluke which is called the 

 miracidium. These miracidium are mi- 

 croscopic in size. They swim about 

 in the water by means of a coat of 

 cilia or small hairs. In this form it 

 lives only from one to three hours un- 

 less it finds a right handed snail. The 

 miracidium does not penetrate into a 

 left-handed snail. Why this micro- 

 scopic immature fluke does not pene- 

 trate into a left-handed snail or how it 

 can tell a right-handed snail from a 

 left-handed snail is a phenomenon that 

 no one as yet has explained. Neverthe- 

 less, this is a fact and a very import- 

 ant one in the control of liver flukes. 

 If there are no right-handed snails in 

 an area then there will be no liver 

 fluke disease. It we find right-handed 

 snails in an area we know that liver 

 fluke disease will undoubtedly make its 

 appearance in that dlHlrict unless we 

 destroy these right-handed snails, which 

 can be done In most districts by means 

 of broudi:aHtiiiK copper sulphate. 



The miracidium has two stages of 

 development within the snail. The time 

 required for this development Is from 

 50 to 80 days. When the final dovolop- 

 mcnt has taken place the Immature 

 fluke leaves the snail in lln; form tit 

 what Is called u riri-.swIninilhK cir- 

 curlue. Kor every nilincldliiin thai pen- 

 elrales Into the right handed suiiil there 

 develops anywhere from 15 lo 10H free- 

 HWlnimlng cercarlae. These cercurlae 

 resenilile a tadpole in shape, having a 

 flat, heurt-Hhaped body with u long 

 tall. They wiggle around in (he wa- 

 ter and under ordinary conditions attach 

 tlieniHelveH to graKM or leaves. They 

 lose their lull, excrete u sticky Hub- 

 Hlance In wlilirh they eiicyHl thoniHulvuH 

 and which glues them to the Hleni ut 



grass or leaf. If they do not become 

 attached to a stem of grass or a leaf 

 they encyst themselves with a sticky 

 substance and float around on the wa- 

 ter. A susceptible animal that comes 

 along and eats grass that has these 

 cysts on it or drinks water that con- 

 tains these encysted cercariae becomes 

 infested with flukes. When these en- 

 cysted cercariae are taken into the 

 stomach of a susceptible animal the 

 cysts are absorbed and the young flukes 

 liberated. These young flukes then 

 penetrate through the walls of the in- 

 testines, get into the body cavity where 

 they wander about and in about 14 

 days reach the liver. When they reach 

 the liver they penetrate the liver cap- 

 sule, get into the bile ducts where they 

 grow to sexual maturity and the whole 

 cycle starts over again. The time re- 

 quired for the completion of their life 

 cycle from egg to egg is from six to 

 eight months. 



In cooperation with the Zoological 

 Division of the United States Depart- 

 ment of Agriculture, the Livestock 

 Sanitary Board has located most of the 

 areas infested with liver fluke. So far 

 we have never found a case of liver 

 fluke east of the the foothills of the 

 Ilocky Mountain Divide. Practically all 

 areas infested with the fasciola hepat- 

 ica are west of the Rocky Mountain di- 

 vide and a small area on the eastern 

 slope of the Hocky Mountain Divide. 



This condition is of particular inter- 

 est to sportsmen and all interested in 

 wild game life. It is not a question of 

 sheep or cattle being on a range. Deer 

 and elk are just as badly infested as 

 sheep or cattle. How long these flukes 

 have been in this country no one 

 knows but probably long before there 

 were any domestic animals. As long 

 as we have right-handed snails we will 

 have liver flukes because there are al- 

 ways susceptible animals wandering 

 around. Ordinarily liver fluke infesta- 

 tion does not kill mature animals but 

 if a young animal becomes heavily In- 

 tested with these liver flukes the death 

 loss may be considerable. In this 

 country infestation generally takes 

 place between July and the third frost 

 In September or October. 



Sheep may be Indlvlduully treated 

 with carbon tetrachloride but it Is dan- 

 gerous to treat cattle wllh carbon telra- 

 i'hlorlde and of course when we conic 

 to wild life like deer and elk, Individ- 

 ual treatment Is out of the question. 



In many districts, however, we nniy 

 prevent liver fluke InfeHlatlon by kill- 

 ing off right-handed Hnalls. Ulght- 

 liamled snails are very easily destroyed 

 by nieunH of copper sulpliale and by 

 proper drainage of Intesli'd aruuB. 



Dr. Hoberl Jay Blutes that; "Copper 

 HUlphutu kills the snallH, the nilriiclilla, 

 and the free-MwImmluK curcurliui. It 

 does not Injure the fluke eggs ur the 

 encyKird cer<'»rlae, therefore, to pre 

 vent InfeMlallon, lliu hiiuIIh hIuiuUI be 



destroyed bef> I] • il.. .*,ii-r and grasses 

 are infected. 



"In the dilutions used for killing 

 snails, copper sulphate is not Injurious 

 to grasses, flowering plants, or to live- 

 stock which drink it. It will kill the 

 low^er form of plant life, such as the 

 algae and mosses and will kill tish." 



It has been our personal observation 

 that copper sulphate will kill fish and 

 especially trout in very dilute quanti- 

 ties. Therefore, to treat our running 

 fish streams with copper sulphate is 

 out of the question. 



We can, however, treat marshes, stag- 

 nant water holes and quite a number 

 of our ponds without injury to game 

 fish. 



Dr. Maurice C. Hall, chief of the 

 Zoological Division of the United States 

 Bureau of Animal Industry, has ttae 

 following to say; 



"In view of the fact that snails are 

 essential as intermediate hosts in the 

 lite history of the liver fluke, it is 

 highly desirable to destroy tJie snails in 

 flukey areas, as any young flukes which 

 hatch and tail to find a suitable snail 

 are incapable of ever infecting sheep 

 or cattle. The best known method of 

 destroying the snails is by means of 

 copper sulphate. Walton, in Europe, 

 recommends spraying the pasture, either 

 with a knapsack sprayer or with a 

 power sprayer, using on dry pastures 

 a Vz per cent solution made by dis- 

 solving a half pound of copper sulphate 

 in lU British or imperial gallons of 

 water. The British gallon contains 16U 

 fluid ounces; the United States gallon 

 contains l-'S fluid ounces. A solution 

 of approximately Va per cent would cull 

 for 12.5 U. S. gallons of water lo a 

 half pound of copper sulphate. In his 

 experiments he found that it would 

 require from SO to 137 gallons of the 

 solution to spray an acre, or usually 

 from luo to 120 gallons. The cost was 

 about 11.75 an acre plus labor cost. 

 When surface water Is present the 

 strength of the solution should be in- 

 creased to I or 2 per cent, or even 

 stronger It necessary. For largo arcus 

 of swampy land, Walton suggests broad- 

 casting with 1 part of powdered copper 

 sulphate by weight lo i to S ports of 

 fine, dry sand; this costs about ii.M 

 an acre plus cost of labor and sand. 

 For the margins of ponds and dttchoH 

 he KUggOHls the use of u dust nuule of 

 1 part by weight of powdered copper 

 sulphate to -I parts of kaolin tchlnu 

 clay); this cosls about )3.0U an acre 

 plus labor cost. SubstaucoH other than 

 sand or kaolin (o mix with copper sul- 

 phate tor liroadcaMtlug or dumlnK mlgbl 

 bo found." 



Wo have looked Into this eoiidlllon in 

 wild anlnuilH as well an In donieallc 

 animals and Just this full wo uiudo n 

 cuuHuary Miirvey of (ho Sun Klvor coun- 

 try. Appuronlly ihuro Is not Hufflcloni 

 liver fluke tnfoHlutlon In thai dlslrlct 

 lo cauHu serious alarm ul Ihls timo. 



