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This article was published in 1956
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
LIVER FLUKE
Control With Copper Sulphate
C. D. GEE, B.V.Sc., Inspector of Stock, Condobolin.
The control of Liver Fluke of sheep and cattle by a direct attack against the "fluke snail" has been advocated, of course, for many years. The particular fresh-water snail involved (Simlinea subaquatilus) is the essential host of the Fluke parasite, and consequently where the snail has been destroyed, or does not exist naturally, the life cycle of the parasite cannot be completed: and the disease cannot occur.
Bluestone has been used for a very long time now for the control of the fluke snail, and with a widely varying degree of success. In fact, Robinson ("The Stock Inspector", 1954), in discussing some experimental work with various chemicals considered likely to supersede copper sulphate, said: "Ever since the inception of copper sulphate as a molluscacide it has been realised that this chemical had certain serious drawbacks; not least among these being the rapid rate at which the concentration fell below the amount required to kill snails. Furthermore, in alkaline water it rapidly formed basic copper carbonate, which is insoluble".
However, and apart from any chemical considerations, the use of copper sulphate often has been regarded by owners as an arduous and expensive task, and for this reason many of them have preferred to adopt the fundamentally unsound attitude of reconciling themselves to living with the discase, and attempting to control the Fluke by attacking, with drenches, the parasite when it is mature in the liver of the host animal. This method has the added disadvantage, of course, of living also with the damage caused by the parasite before it reaches maturity and becomes accessible to attack by drenching.
Despite the drawbacks of alkalinity, it apparently is a fact that in the past the fluke snail has been controlled on, or eradicated from, very many properties with the use of bluestone applied by various means; and the purpose of this article is to show that, with modern spraying equipment and an intelligent approach, the work can be carried out not only efficiently but economically and without undue effort.
On the property concerned the snails have been reduced to such an extent that the sheep are being drenched for Fluke once only each year, while the owner is considering eliminating such drenching entirely.
TYPE OF COUNTRY: This varies from fairly flat to undulating and hilly. The areas harbouring the snails were well-defined small creeks. There are no large areas of swamp country on the property, and although in places the creeks spread out to form wider swampy areas, these are not extensive.
DRAINAGE: Not generally carried out because of the owner's fear of causing soil erosion. However, the properly carries an excellent cover of improved pasture and erosion should not be a factor to be considered in this case. Only one small swampy area of about sixty yards by twenty has been partly drained. Drainage has a great deal of value in Fluke snail control and can reduce greatly the amount of bluestone required to treat a given area of country.
BLUESTONE SPRAYING: Spraying is carried out twice each year: once in the autumn and once in the spring. Different techniques have been used in the application of the chemical but the unit which so far has proved most efficient and economical is a Land Rover with a power take-off operating a fire-fighting type of spray unit.
The strength of the bluestone solution used is 10 per cent or greater; the procedure being to dissolve as much bluestone as any given quantity of water will take comparatively easily.
The spraying is restricted largely to small creeks and a large number of small tanks. There is no hard and fast rule as to how extensive an area on each side of the creek is sprayed; the spray simply being applied wherever there is water or mud likely to be harbouring snails. Normally dry portions of the creek beds are missed and the extent of the spraying is greatly increased where the creeks spread out to form wider swampy areas.
The average width of country treated along the creek beds would be about six feet, and the approximate length of creeks treated about twelve miles. In addition, seventy tanks averaging about 500 cubic yards in capacity are treated; the edges of the tank being given special attention, but the whole of the surface of each sprayed. The owner considers that this has other beneficial effects; such as the control of Algae in the tanks.
The drainage does not all originate on this owner's property, but all catchments draining on to the holding are treated with permission of the adjoining owners. In addition, drainage from the property is treated to a distance of about fifty yards from the boundary fence. The total length of creeks treated in this way would be about two miles, of the total twelve miles mentioned above. A rough estimate of the actual amount of surface to which the spray is applied is fifteen (15) acres.
The finest commercial bluestone is used, and four or five cwt. is applied twice a year. As stated, the application is at about 10%; so that the amount of fluid used per treatment would be four or five hundred gallons per treatment, or about thirty gallons to the acre.
COST OF TREATMENT: The cost per treatment for bluestone and labour only is £80, or £5/6/- per acre for the 15 acres actually sprayed. No information is available regarding other costs, but the owner is of the opinion that costs other than for labour and the chemical are negligible.
In terms of the cost per acre of country kept free of Fluke in this manner, the relative figures are 5½d. per acre per treatment, or 11d. per acre per year,
COMPARATIVE COSTS: It is interesting to draw a comparison between the cost of treating this property twice a year with bluestone and the cost of a drenching campaign such as would be necessary to control Liver Fluke if the bluestone treatment were not carried out.
As mentioned above, the cost of applying bluestone is £80 per treatment or £160 per year. If the bluestone treatment were not carried out, drenching for Fluke would have to be undertaken up to six times per year. The cost of sufficient single strength Carbon tetrachloride to treat the 5,000-odd sheep on the property would be about £8/6/- per treatment, or £50 per year. Add to this the cost of labour, which would be not less than four man days, or about £12 per treatment or £72 per year.
The cost, then, for drench and labour would be £122 per year, as compared with a cost of £160 to keep the property free of Fluke by treatment with copper sulphate.
However, drenching never can be expected to keep sheep entirely free from Fluke, and even with such a drenching programme in operation there still would be some Fluke damage to the livers between drenchings. This would result in loss of production due to unthriftiness, as well as the possible sickness or death of sheep. It must be remembered also that there is a degree of risk of poisoning with Carbon tetrachloride drenching, and that losses from that cause, when they do occur, are always heavy.
EFFECTIVENESS OF TREATMENT: The treatment of this property, which is situated in the heart of the area accepted generally as the "home" of Fluke in New South Wales, has reduced infestations in the sheep to a particularly low level. In fact, the parasite seldom is seen in the livers of killers at the present time, and several post-mortem examinations carried out by the writer have failed to reveal a single Liver Fluke or any sign of Fluke damage.