« PreviousContinue »
"Trekking" and grass burning are old methods, but even yet often employed, for ridding flocks or herds of disease.
One of the farmers' favourite summer grazing sections of South Africa, is the High Veld. Over this area -lying between 4 000 to 6 000 feet of altitude the ticks which transmit diseases are limited or nearly limited to B. decolaratus and R. evertsi, due to the fact that the other ticks cannot withstand the winter temperature. In the winter the stock farmers travel with their animals to the warm low veld, where the grass is abundant. If their animals become sick from some of the "tick diseases," they trek back to the higher country, where the disease would disappear.
By burning off the dry grass, the new green grass comes up much sooner and will furnish grazing for cattle and sheep at a much earlier date. Some farmers noticed that after the grass had thus been burned off, the animals suffered far less from ticks; the practice then came to be adoptad against the ticks themselves.
The starvation method of eradicating ticks - which has been so successful in the Southern United States, against B. annulatus · - has been tried in South Africa, but has not been so effective. Generally here the question is not only the eradication of the blue tick, but also of the brown and red ticks and the Bont tick. In theory even these could be destroyed by placing all the animals in B (see the annexed diagram) and keeping them there for a period of 15 months; then transferring the animals to C and keeping
them there for 18 days; then moving the cattle to D (so that the ticks which have dropped off in C will not have the time to moult and again seek the host) and keeping them there for another 18 days; and finally turning the animals - which are tick free into A. B, C and D could be closed against cattle for 14 to 16 months and the farm thus freed of ticks. This method in theory would rid the farm of all the ticks which are known to transmit diseases to oxen, horses, sheep and goats. In practice, however,
the starvation of ticks is not so easy, owing to the number of wild animals which will act as hosts to the ticks, thus carrying them over the starvation period. Of those ticks which transmit disease, but two species -B. decoloratus and R. capensis - do not find a host on the wild animals. The wild hosts of the other common African ticks are the following:
Amblyomma hebraeum: lion; wild dog; various antelopes; buffalo; giraffe; ostrich. Rhipicephalus appendiculatus: lion; various antelopes; buffalo; Cape hare. Rhipicephalus evertsi: reed buck; various antelopes; giraffe; Cape hare. Rhipicephalus simus: lion; wild dog; jackal; bush pig; hedgehog.
In an actual trial of the starvation method carried out by H. E. Laws in the East London district, it was seen that the blue tick can be starved, but also that R. capensis seems to have some host among wild animals which has not been observed. Hares and duiker (one of the antelopes) which had been running on the experimental area were tick-infested when shot. The usual and the most successful method employed in South Africa against ticks is dipping. The dipping fluid found most useful is that recommended by Pitchford, which is
51⁄2 lbs. of soft soap;
2 gals. kerosene ;
81⁄2 lbs. arsenite of soda;
Even dipping has its disadvantages, if the farmer has many species of ticks to destroy. If only B. decoloratus is to be destroyed, dipping every three weeks will suffice; if R evertsi is to be destroyed the dipping would have to be done every week; if also the brown ticks (Rhipicephalus sps.) are to be destroyed, dipping would have to be done every three days. In order to make dipping every three days possible, the above formula has been modified to: 3 lbs. soft soap; I gal. kerosene, 4 lbs. arsenite of soda (20% arsenic); 400 gals. water. In farms of over one or two thousand acres, dipping every three days would seriously interfere with any other farming operations; it seems more practical to dip every week and continue the dipping over a number of years.
44- Nodular, Intestinal and Ganglionic Helminthiasis.
GRIMALDI, ERCOLE: L'Helminthiase nodulaire, intestinale, et ganglionaire. — Hygiène de la Viande et du Lait, Year 6, No. 11, pp. 596-610. Paris, Nov. 10, 1912.
In this article, which contains the results of observations made in the Municipal Abattoirs of Genoa, the writer, after giving a review of the literature on the question, calls to mind the fact that nodular helminthiasis attacks a large number of domestic animals and some wild species, being of general occurrence. It is found in cattle, sheep and pigs, and also infests deer. It occurs in Europe, Algeria, Tunis, America, Australia and Japan and, like all parasitic diseases, spreads especially quickly among wild animals. The nodular helminthiasis of cattle is due to an osophagostomosis and attacks by preference young animals.
The eggs, which are disseminated by infected cattle, when they fall in suitable places, hatch out and the larvæ become free. It is not known whether the latter have an independent life in the ground, or pass into an intermediate host. The eggs are laid at the beginning of autumn and the larvæ at the same season penetrate into the intestines of the animals. Water is probably the vehicle of infection in the case of cattle. This parasitic disease is never found in dry districts, but occurs in those which are irrigated and where the water has remained stagnant for some time. The larvæ, having found their way into the intestine, penetrate the mucous membrane by means of their rapid movements and reach the sub-mucosa, where they usually remain. Some of them, however, traverse the muscle layer and find their way beneath the serous layer, while others penetrate into the ganglia of the mesentery by way of the chyliferous ducts. Having penetrated into the thickness of the wall of the intestines, or below the serous layer, or even into the ganglia of the mesentery, the larvæ cause the formation of nodules, within which they remain for some months. But while those which are in the walls of the intestines emigrate towards the intestinal aperture from June to July, the others never succeed in overcoming the hindrances in their path and perish within the nodules. Having reached the intestine, the parasites differentiate sexually, and eggs are produced; these are expelled with the faeces and set at liberty larvæ ready to infect new hosts. The disease is characterised anatomically by the occurrence of nodules containing a nematode larva, in the course of the intestines and in the ganglia of the mesentery. The lesions of the ganglia have an undoubted similarity to those of tuberculosis and a confusion between the two might lead to very serious consequences. Bilharzia crassa also produces a helminthic form of nodule, which differs in its smaller size and its less resistant capsule. Tubercle nodules differ from the parasitic ones chiefly in that the former contain more caseous than purulent matter, and are clearly isolated from the surrounding tissues, besides being often surrounded by small tu bercles.
The most characteristic symptom of nodular helminthiasis is severe diarrhoea, the fæces being greenish and watery; this attacks several animals at once and assumes an enzootic character. The disease lasts about twɔ months, and then gradually disappears; its evolution is slow and progressive. The sick individuals are low-spirited and emaciated; they suffer from pica and sometimes die exhausted by diarrhoea during the cachexic period. From researches carried out by the writer on a large number of cattle, it seems logical to conclude that:
1. Bovine nodular helminthiasis is due to an Osophagostoma larva. 2. The larvæ leave the nodules to penetrate into the intestine in the months of June and July.
3. Contrary to what is maintained by some writers, the mesenteric ganglia can fairly frequently take part in the infection process and also simulate very closely one form of tuberculosis.
45- Wireworms in Sheep and their Treatment.
THEILER, ARNOLD in The Agricultural Journal of the Union of South Africa, Vol. IV, No. 4, pp. 572-586. Pretoria, October, 1912.
The writer first describes the development of the wireworm (Strongylus contortus) which lives in the fourth stomach of the sheep (1) and sucks nutriment from the mucous membrane (2). The female worm lays eggs which leave the sheep's body with the droppings. The eggs hatch out at a temterature of 40° to 50° F.; the young worm feeds on the organic matter of phe manure and reaches the so-called ensheathed form, which withstands the influence of cold or dryness. This ensheathed form grows into the adult stage in the stomach of the grazing sheep, being taken up with the grass.
It is thus very necessary that the pastures should be kept free from infection. To this end, the sheep-breeder must always have at his disposal some pasture, on which no sheep or other ruminants have been grazing for at least nine months to one year. If, however, a flock is infected, which can be ascertained by examining the sheep manure, the worms must be got rid of by dosing the sheep, and the flock should be driven to a clean pasture. If the sheep again show signs of infection, for the parasites are not always all killed by dosing, this treatment should be repeated. By adopting this system of dosing and moving on to cleaned ground, it will in time be possible to eradicate the disease.
The grass of the infected pastures should be burnt each time on the removal of the sheep. Where, however, change of pasture and burning the grass are impossible, the repeated use of vermicides is the last resource.
The two best known medicines for dosing sheep are bluestone and "Cooper's Dip" and lately they have been used in combination. The result of a series of experiments as to the safe maximum dose of this mixture may be summarized as follows:
For sheep from 4 to 8 tooth: 15 grains of Cooper's Dip and 15 grains of bluestone.
For sheep of 2 tooth: 10 grains of Cooper's Dip and 10 grains of bluestone.
For lambs from five months old: 71⁄2 grains of Cooper's Dip and 7% grains of bluestone.
Experiments proved that smaller doses were effective and accordingly the doses recommended were as follows:
Sheep of 4-8 tooth: 10 grains of Cooper's Dip and 10 grains of bluestone. Sheep of 2 tooth: 7 grains of Cooper's Dip and 7 grains of bluestone. Lambs, six to nine months old: 5 grains of Cooper's Dip and 5 grains of bluestone.
It was found that one dose did not in every case destroy all the worms; therefore experiments were made as to how often, and with what intervals, these remedies could safely be used and it was found that sheep could be
(1) It also occurs in the goat, deer and cow.
(2) See No. 1544, B. Nov. 1912.
dosed ten times at weekly intervals with the maximum safe dose and thus freed from the parasites. This also applied to lambs.
Further experiments were made as to the effect of the above-mentioned remedies: 30 pregnant ewes were given, from some days up to some weeks before lambing, the whole or the half of the maximum dose; this was followed (in two instances where twins were born) by the death of the twins. This may be due to the actual dose, since in one other instance where the twins survived, the ewe had only been given half the safe dose.
The dosing of ewes with the maximal dose of Cooper's Dip and bluestone, given on the day of lambing or some days after, had no bad effect on the suckling lambs.
A second method of dosing sheep is by placing a lick of bluestone, Cooper's Dip, slaked lime, sulphur and salt in troughs to which the sheep could have free access. Although they each consumed on average 2.3 grains of Cooper's Dip and 2.3 grains of bluestone daily over a period of three months, these remedies had no effect in improving their condition. Thus direct dosing with the mixture is preferable to the use of the lick method. Other remedies are "Kamala ", a medicine which is at present being tested, and "Bert Bowker's Powder ": this, according to the farmers, seems to have the desired effect.
46 The Action of Anthelmintics on Parasites located outside of the Alimentary Canal.
RANSOM, BRAYTON HOWARD and HALL, MAURICE C.: U. S. Department of Agriculture Bureau of Animal Industry, Bulletin No. 153, 23 pp. Washington, 1912.
This paper gives a systematic summary of all previous work concerning the use of anthelmintics against parasites located outside of the intestinal lumen, and also details the results of some attempted medicinal treatment of sheep for tapeworm disease (Chysanosoma actinoides). From the literature quoted, it appears that anthelmintics have been claimed to be efficacious in 8 cases of human somatic taeniasis (male fern); inefficacions in 8 cases of somatic taeniasis in the lower animals (male fern); inefficacious in at least 6 cases of intestinal and extraintestinal thysanosomiasis (carbon bisulphide and male fern); efficacious in over 14 cases of hepatic distomatiasis (carbon bisulphide and male fern); efficacious in 8 cases of venal distomatiasis (salvarsan); inefficacious in 5 cases of venal distomatiasis (salvarsan); and efficacious or inefficacious, according to various authors, in an indefinite number of cases of venal distomatiasis (male fern). Objections based on a critical examination of the cases are made by the writers to these figures; on the other hand their experimental results (with carbon bisulphide and male fern) were negative. However, the total evidence collected here indicates that further work along this line is necessary and desirable.
(A bibliography of 43 papers is appended).