ROT (FASCIOLOIDIASIS) IN

By A.A. KING-SCOTE'

INTRODUCTION A sometimes serious and fatal liver disease of , , , and A1 is caused by the large American , magna (Bassi, 1875). The parasite was first observed by Bassi in , to which country it bad been introduced by an American Elk (Cervus canadensis). The flukes spread to deer in Italy and Southern Germany causing enzootic liver rot disease (Swales (1) ). In the United States Dillon (2) reports F. magna was first recorded at an early date in white-tailed deer of the west and subsequently spread eastward in deer and elk. In 1934 flukes were found in deer and moose of the upper Michigan Peninsula and twelve years later the parasite was recorded in Cer- vidae of the lower Peninsula. Olsen (3) in 1949, states 69 per cent of the white-tailed deer in Texas were infested. At an abattoir in Logan, Utah, 867 out of 2,364 cattle were condemned because of liver flukes. These con- demnations represented more than 9,500 lbs. of liver. No figures were avail- able for weight losses or interference with milk production in cattle or from stunting and deaths in sheep (Krull (4)). In Canada, the parasite was observed by Hadwen (5) in 1915 in deer of British Columbia. Swales (1) studied infestations of F. magna in the buffalo, elk and other in 1935 and conducted extensive researches on the life history, and published a paper with specific reference to liver flukes in deer (Swales (6)). Concern regarding the existence of F. magna in Ontario arose when meat inspectors observed beef livers from the Burwash district seriously damaged by the flukes. Subsequent investigations revealed elk and buffalo which had shared ranges with the infested cattle, were also parasitized. A herd of over 400 Hereford cattle and a large flock of Oxford sheep were involved in the Burwash, Ontario, enzootic. Swales (7), Fallis (8) and Clarke (9) report other records of the para- site from the Rainy River and Kenora Districts and Frontenac County, res- pectively. Until the summer of 1949, therefore, knowledge regarding the distri- bution of the flukes in Ontario was limited to three widely separated locations in the central and extreme eastern and western parts of the Province. It was considered advisable to obtain definite data on the range of the parasites and specific information on their incidence in wild and domestic ruminants with the ultimate object of curtailing the spread of fluke disease. A survey was organized and preliminary information was obtained jointly by personnel of lDepartment of Parasitology, Ontario Veterinary College, Guelph, Ontario [2031 Canadian Journal o' LIVER ROT Vol. XIV, No. 6 [204]' Comparative Medicine June, 1950 the Fish and Wild Life Division (Ontario Department of Lands and Forests) and the Ontario Veterinary College (Ontario Department of Agriculture). *~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~...... -.1......

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Fig. 1. Large American Liver Flukes, FaEcioloides mamna (Bassi, 1875), (x2). Right, dorsal; left, ventral. MORPHOLOGY AND LIFE HISTORY The large American liver flukes are aptly described by hunters as re- sembling "blood suckers" or "leeches". The adult worms are thick and flesh- coloured measuring up to 100 by 26 mm. Individual adults produce an estim- ated 6000 eggs per day. The eggs are oval, operculated at one pole and mea- sure 109-168 by 75-96 microns. The life history has been described in detail by Swales (1). Briefly, the eggs are passed from the liver of natural hosts, through the bile ducts to the intestines and then out of the host's body with the droppings. Only those eggs which reach water or wet ground complete their development. The larval flukes (miracidia) take a month or longer to hatch. The young flukes, only complete the next stage of their lives (sporocysts and rediae) in certain aquatic or amphibious species of snail. (Fossaria parva and Stagnicola palustris nutta- ana) in Canada. Growth and multiplication in the snails takes 7 to 8 weeks. For each young fluke that enters a snail a great many may emerge as cercariae. These larvae attach themselves to aquatic or shoreline vegetation and be- come cysts which are resistant to a variety of climatic conditions for at least three months. Any suitable (usually ruminants) which feed upon plants contaminated with cysts may become infested with the flukes. The pa- rasites take. about five months to reach maturity in the liver. The flukes normally complete their life cycle in wild ruminants. In do- mestic animals when they ultimately reach the liver, they cause violent tissue reactions which encapsulate the worms and prevent escape of the eggs. Canadian Journal of LIVER ROT Vol. XIV, No1 6 Comparative Medicine June, 1950 [205] PATHOGENFSIS Sudden infestation of animals with large numbers of larval flukes, whikh penetrate the intestinal wall and wander about the body cavities, may cause death in a relatively short time. In cases where infestation is moderate and gradual no signs of ill health are usually observable. Later, when the worms commence to burrow into the liver, tracts, cysts, abscesses and secondary bac- terial infections may destroy much liver tissue. These lesions, in the advanced stages, are associated with marked dark pigmentation of the liver surface and associated lymph glands. The flukes are usually found in pairs, within cysts containing a dark liquid. In chronic cases the lesions become calcified, scar tissue is formed and the livers become rough, irregular and lumpy. Succeed- ing years of infestation result in progressive and permanent damage to the livers. The classical symptoms of the disease are "bottle-jaw" (a swelling in the intermandibular space), anaemia and jaundice associated with unthrifti- ness. These symptoms, however, are not always constant. Cervidae are the natural hosts of F. magna and tolerate moderate infes- tations. Deer and elk in Ontario containing up to 30 flukes per liver show little ill effect from the parasites. Olsen (3) on the other hand described cysts and destruction of 10 per cent of the livers of Texas deer with 30 flukes. The great damage that large numbers of flukes are capable of causin-g in Ontario has been demonstrated in the elk herds of Pembroke and Burwash and in a herd of over 400 Herefords in the last named district. Cattle and sheep which are unnatural hosts of F. magna suffer severely even with light infestations of the parasites. DtIAGNOSIS The most certain method of recognizing F. magna infestations is by find- ing the parasites in the livers by cutting the latter into thin slices. F. magna

Fig. 2. Section of beef liver showing extensive chronic pathological changes caused by. F. magna Canadian Journal of LIVER ROT Vol. XIV, No. 6 [26[206] Comparative Medicine June,19N0 must be distinguished from , which is a smaller fluke with a pronounced cone protruding from the anterior end. Dicrocoelium dentriticum a still smaller fluke than the preceding species; it is 5-12 mm. long and 1 mm. wide. The eggs of F. magna may be found with the aid of a microscope in the bile or droppings of infected natural hosts. For dropping examinations sedi- mentation methods of egg concentration are used. Flotation techniques are un- satisfactory. INCIDENCE OF F. MAGNA IN THE RUMINANTS OF ONTARIO The results of the 1949 summer and fall survey revealed F. magna over a much greater area than had been expected. Sixteen counties or districts with a total of 42 townships or localities were checked. Deer, elk, and/or moose were found infested with the parasit-es in 11 counties or districts viz: - Renfrew, Hastings, Peterborough, Frontenac, Bruce, Carleton, Algoma, Ni- pissing, Rainy River, Kenora and Sudbury. In Ontario 203 deer of various ages from widely separate localities were examined. Ninety-one livers examined showed 13.2 infested with from 1 to 31 flukes. Microscopic examination of 112 deer droppings revealed 11.6 per cent animals infested withe F. magna. Records obtained regarding the incidence of F. magna in elk during 1949 and preceding years showed 78 positive on post mortem and 36 per cent posi- tive by faecal examination in 77 animals checked. These results are exclusive of known super-infested herds. Ten moose droppings showed an incidence of 40 per cent infestation with F. magna. One moose liver examined was negative. As regards domestic animals available records indicate that during the past decade approximately 1200 head of cattle and sheep in Ontario, have suf- fered or died from fluke infestation. In 1949, 9 flocks of sheep (all in one district) out of 29 flocks examined in the Province, harboured F. magna. Forty-four beef livers in one abattoir were infested. DISCUSSION The information gathered during preliminary studies of F. magna in Ontario indicates that flukes are widely established in the Cervidae of the Prov- ince and have caused several enzootics among domestic animals. Elk with an average of 58 per cent infestation are the main reservoir of the flukes, and as such are the greatest danger in spreading and increasing the incidence of the di- sease among their own species as well as deer and moose. Some five hundred elk are estimated to be superinfested with flukes at the present time. Other herds known to be infected on restricted ranges, if they increase in numbers, may be expected to follow a similar fate. The high incidence in elk is attributed to their original importation from a liver fluke area (Wainright) ; their habit of herding, often on restricted ranges and to their feeding habits. Canadian Journal of LIVER ROT Vol.J-XIVNoe 6 Comparative Medicine June, 1950 [2071fL7J The white-tailed deer (Odocoileus virginianus) in Ontario, as has been indicated, show an overall incidence of approximately 12 per cent infestation with F. magna in Ontario. This is comparatively low when compared with the degree of parasitism in elk (58 per cent) and white-tailed deer in Texas (69 per cent). Up to the present, F. magna in Ontario deer has not been observ- ed to cause any serious damage. The parasite, however, is a potential danger and will be serious if it increases to the point where it produces ill health or losses in deer, and they in turn spread it more frequently to domestic animals. Swales (1) has pointed out that super-infestations with F. magna are encountered in areas abnormally crowded with definitive hosts and rich in suitable snail life. The wide spread distribution of F. magna together with information obtained on preliminary snail surveys, indicate that suitable snail intermediate hosts exist over large areas of Ontario.

CONTROL Control of F. magna must be primarily directed toward preventing the increase of the parasite within the Province, in order to conserve the health of domestic ruminants and native Cervidae. Elimination of the introduced elk herds as the main reservoir hosts of flukes is recommended. Increases in the sizes of the elk herds, already distributed widely throughout Ontario, may be expected to result in dispersal, perpetuation and increase in the incidence of flukes. The movements of deer, to private herds and parks, from known danger- ous areas should be avoided. Careful maintenance of deer populations, keeping their numbers within reasonable bounds, to prevent overstocking, will do much to prevent super-infestations with F. magna. It has been demonstrated at Burwash, Ontario, that enzootics of fascio- loidiasis may be controlled in cattle and sheep by the combined administration of hexachlorethane, the eradication of snails with copper sulphate and selection of pastures and hay from safe' ground. The methods of using hexachlorethane described by Alicata (10) have been applied successfully in Ontario. The snail intermediate hosts on farm lands have been controlled by the intelligent use of copper sulphate in streams and bogs by following the procedure recommended by Ross and Gordon (I 1). SUMMARY The history of the large American liver fluke (Fascioloides magna) and its life history are briefly reviewed. The results of a survey made in 1949 are given revealing the incidence of the parasite in domestic ruminants and the deer, elk and moose of Ontario. Recommendations are made regarding control measures. Canadian Journal of Vol. XIV, No. 6 [2081 Comparative Medicine ALGAE POISONING June, 1950 RESUME L'auteur repasse brievement 1'historique et la biologie de la grande douve hepatique d'Amerique, son role pathogene et le diagnostic de l'infection. Les resultats d'une etude poursuivie en 1948 sur la frequence du parasite chez les ruminants domestiques, le chevreuil, le caribou et l'orignal en Ontario sont rap- portes. Des moyens de controle de l'infection sont aussi recommandes. REFERENCES 1. SWALEs, W. E. The life cycle of Fascioloides magna (Bassi, 1875) the large liver fluke of ruminants in Canada. Can. J. Res. 12: 177-215. 1935. 2. DILLON, W. R. Personal communication to W. J. K. Harkness. 1949. a. OLsN, 0. W. White-tailed deer as a reservoir host of the large American liver fluke. Vet. Med. 44: 26430. 1949. 4. KRuLL, W. H. Liver fluke causes serious losses to sheep and cattle in the intermountain States. U.S. Bureau of Animal Industry. 5. HAWDEN, SEYMOUR. A new host for Fasciooides magna, Bassi, together with observations on the distribution of Fasciola hepatica, L. in Canada. Amer. Vet. Med. Ass. 49: 511-515. 1916. 6. SWALES, W. E. Researches on liver fluke in deer. Transactions of 21st American Game Conference, New York City, Jan. 21-23, 406-411, 1935. 7. SwALES, W. E. Personal communication. 1949. 8. FALLS, M. Personal communication. 1948. 9. CLARKE, C. H. D. Personal communication. 1949. 40. ALICATA. J. E. The control of liver fluke of cattle in Hawaii. Circular 25, Univ. of Hawaii Agricultural Experiment Station, Honolulu, T. H. 1946. 11. Ross, CLUNIEs I, and GORDON, H. McL. Internal parasites and parasitic diseases of sheep. Angus and Robertson Limited, Sydney, 1936.

REPORT ON ALGAE POISONING A.F. MacKINNON1 D URING 1948 and 1949, a number of cattle in the area around the shores of Sturgeon Lake, Ontario, was affected by a condition of unknown origin. Within the two-year period, about 20 of these animals died and ap- proximately 18 were treated by the writer. The condition was characterized by stupor and in other instances un- consciousness. The patient usually would not eat or drink for four or five days. During that time, it remained comatose. The head and neck were extend- ed and in some cases retracted. Sixty cc. of Thio-nitrite, Stronger (Pitman Moore preparation for the treatment of prussic acid poisoning) were given intravenously to each cow. In addition. Thio-nitrite tablets (Pitman Moore - sodium nitrite 10 grs.; so- dium thiosulphate 50 grs.) were given every four hours. Each animal was also given one-half gallon of mineral oil and a gastric sedative. The 18 animals to which this treatment was administered responded favourably and recovered. I Bobcaygeon, Ontario.