TICKS ON FARM ANIMALS

Pukekohe & Waiuku Times, Volume 7, Issue 356, 1 March 1918, Page 4

TICKS ON FARM ANIMALS

By C. J. Keakes, D. V.Sc, M.R.C.V.S, Director Live Stock Division.

(Reprinted from "The Journal of Agriculture.")

Officers of the Live Stock Division have lately made a special investigation into the apparently unusual prevalence of ticks upon cattle, dogs, horses, and occasionally sheep, in portions t>f the northern Auckland district. For this purpose Mr W. T. Collins, M.R.C.V.S., Government Veterinarian, spent some time in the district, and went fully into the whole of the questions involved, particular attention being directed to the point,whether any diseased condition of cattle was associated with the presence of these ticks. Prior to joining the New Zealand Government service Mr Collins had been od gaged in special post-graduate work at the laboratory of the Royal Veterinary College, London, and the experience there gained in the scientific side of veterinary work has rendered his services of particular value to the Department. A considerable amount of concern and uncalled for alarm has been felt by settlers and others on account of the presence of these ticks, it being feared that the Dominion was faced with the necessity for combating the serious disease of cattle known as tick fever, which exists in Queensland, the United States, and some other countries. It should be made clear that the presence of ticks on cattle in New Zealand does not imply the existence of this disease, which is not, and never has been, present in the Dominion. The degree of significance to be attached to the presence of ticks in the presence or absence respectively of tick fever is made clear in the following extract from a bulletin published in 1917 by the Commonwealth advisory Council of Science and indus'ry (Australia): The cattle tick is the natural intermediary in the dissemination of tickfever, and it is probable that a single infected tick is capable of reproducing the disease in a susceptible beast. The transmission of the disease usually occurs soon after the larval tick attaches itself to the skin of the host, the infection being transbeing transmitted to the larval tick from the infected adult female parent through the egg. Non-in-fected ticks become infected when they feed upon an animal that harbours the piroplasma in its bloodstream. Consequently i those ticks which develop upon cattle that have not suffered tick fever, or upon other animals naturally insusceptible to the fever, are incapable of spreading infection. This fact accounts for the absence of tick fever in certain centres where the tick has been introduced by horses or sheep. The "cattle tick" mentioned in this extract is of the variety known as Boophilus australis. In North America the same disease is spread through th* agency of a tick termed Boophilus annulatus or Rhipicephalus annulatus, which differs only in slight structural features from the Queensland tick, the life history of the two being practically identical. These ticks have never been discovered here. Two varieties of the ticks have been found in New Zealand, one being named Ixodes ricinus (popularly termed the " dog-tick " or the " castor-bean tick"), the other being a tick of the subfamily known as Hoemaphysalis. Both represent branches of one family termed Ixodinae, of which the Queensland and North American varieties of tick ait also branches. All are blood-suck-ing parasites, and probably all are capable of acting as carriers of tick fever when that disease exists among cattle, but nr.ne of them can set up the disease independently.

In Great Britain and other European countries Ixodes ricinus acts as a carrier of the infection of a form of red-water affecting cattle. This disease does not cause any serious loss to British farmers, and has never been found in New Zealand. We occasionally get cases here of what is termed red-water, but this trouble is due to dietetic causes, and when taken in time is readily curable by a change to a more nutritious diet containing plenty of albuminoids, combined with simple medicinal treatment.

Tick fever, technically known as " piroplasmosis," is a specific disease of cattle caused by a protozoan parasite, termed Piroplasma bigeminum, which is found present in the blood of affected animals; and ticks, being blood - sucking parasites act as carriers of infection from animal to animal. So long as we can continue to keep this disease out of the Dominion there is nothing to fear from that point of view from the ticks we have here. But these can do harm in other directions if they become very numerous, and on this account it is considered necessary to take steps to control their dissemination, and to go as far as is possible towards eradicating them. The closest inquiry has failed to indicaie any form of sickness or acy serious trouble caused by ticks in New Zealand, but the experience of other countries goes to show that they may, if present in very large numbers, cause trouble to stockowners in the future, even though the serious disease, tick fever, is absent. The directions in which, under the worst conditions, trouble may be caused may be summarized as follows:

(a ) By the lowering of condition through loss of blood when large numbers of ticks are harboured by one animal. (b.) By decreased milk-yield of cows harbouring large numbers of ticks. (c) By deterioration in the value of hides. When large numbers of ticks are present the value of the hide for conversion into leather is reduced It is stated that a badly affected "ticky" hide is worth from Is to 10s less than if sound.

(d) Possible mortality among animals harbouring large numbers of when they nn< already weaken-

Ed by various tormy of sickness, insufficient food, etc. Ticks of the Ixodinae family are found over all Europe, in North and South Africa, .Asia, Australia, and America, and they thrive well in temperate climates, though they appear to multiply most extensively in countries possessing a hot climate. In New Zealand they have been noted almost exclusively in the country lying north of the city of Auckland, the only other specimens obtained having been found in the northern part of the Bay of Plenty district, where their presence has been notified on two occasions only. Inquiry shows the probability of their having been found in the extreme north of Mongonui County some twenty-five years ago, and authentic information has been obtained of their presence in one part of Whangarei County eleven years since. TREATMENT

The Divisional officers have carried out a good deal of experimental work in the direction of ascertaining*, the best form of treatment for destroying the parasites, and it has been found that, in the case of dairy cows and other cattle which can be handled or sufficiently controlled, Stockholm tar isian effective method, as the ticks are killed by it in a few hours. The tar is sprayed on to the infested portions of the skin by means of a small spray pump known as the "Faultless" pump, costing only a few shillings, which was placed on the market for use in spraying garden plants, etc. fa) Kerosene A pint, linseed oil A pint, sulphur loz. (b) Kerosene 10oz., lard lOoz, tar 2oz, sulphur loz. These two mixtures, however, though ultimately destroying the ticks, proved much slower in their actfon than the Stockholm tar. Very strong solutions of sheep dips have also proved effective, but, owing to the strength of the solutions sometimes used, cases have occurred where cattle have suffered from the effects of them. The method of spraying with Stockholm tar can be recommended as the safest and most reliable, and it has been largely used by settlers. All dead ticks must be collected, if possible and destroyed, preferably by burning. As regards run cattle, unaccustomed to handling, dipping is the only effective method available.

It has been found that in New Zealand the ticks are first noted in 'each year about August and September, and are most numerous in November and December. During January their numbers diminish, and between February and August little or nothing is seen of them. CONCLUSION

The question of the best and most effective further measures to be adopted in dealing with ticks will be treated in a future issue of the Journal. Meanwhile it is trusted that the foregoing facta will enable s-tockowners to realize that, though the ticks found here may prove troublesome from the standpoint of monetary loss if they multiply sufficiently, they are not dangerous from the point of view of disease, so long as we can, by maintaining our present quarantine system, keep the specific disease out of the country; also that there is no risk of any kind involved by the movement of cattle from infested districts to others so long as care is taken to prevent them carrying ticks with them.