Report on protective inoculation against tick fever : an account of an experimental inquiry into its effect on cattle, and on meat and milk, together with some notes on protective measures other than inoculation / by FrankTidswell.
- Tidswell, Frank, 1867-1941.
- Date:
- 1899
Licence: Public Domain Mark
Credit: Report on protective inoculation against tick fever : an account of an experimental inquiry into its effect on cattle, and on meat and milk, together with some notes on protective measures other than inoculation / by FrankTidswell. Source: Wellcome Collection.
Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.
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![AV’’c have seeu that iinmuuity against tick fever only becoines coin])lete and lasting as the result of repeated infection. As satisfactory and durable iuimuuity is not secured by a single attack of the natural disease, so the protection of cattle is not finally effected by a single inoculation. The condition of acquired immunity is an artificial one, and the tendency in all such cases is reversion to the natural state. In animals immunised against anthrax, diphtheria, snake poison, &c., it is necessary, in order to keep up the immunity, to occasionally inject virus, toxin, or venom. In vaccination against small-pox, the protection afforded by the infancy vaccination becomes diminished during growth, and requires to be sup- plemented by revaccination after puberty. By analogy, it is to be expected that the acquired immunity of cattle against tick fever, in the absence of reinfection, will gradually become lessened as time goes on. This reasoning induces the suspicion that we may prepare for tick infestment too long beforehand. If we inoculate now, the immunity may be lost again before the ticks come. But on the other hand it is necessary to be ready, for the ticks may come at any time. There are two courses open to us. We can either reinoculate annually until the ticks arrive, or we can attempt to secure an enduring immunity by inoculating and reinoculating several times in succession, with, say, a month or six w'eeks interval between each operation. The first suggestion is based on the view that inoculation is probably most valuable when performed shortly before exposure to ticks, and the interval of a year is chosen as being the time during which the immunity conferred by a single attack has been shown to last, in some cases at least. The second suggestion is based on the view that the immunity becomes intensified by repeated attacks, and is therefore likely to last longer. It has the advantage of picking up the animals that escape satisfactory treatment on the first occasion. It is impossible to be more precise about these suggestions, because they have never been put to the test. But there is little room for doubt that in this Colony, where the exact time of the advent of the ticks is a matter of uncertainty, rcinoculation in some form or other is the wisest plan. The choice of a method must be governed by practicability, but all direct and indirect evidence indicates that the immunity, once obtained, must be maintained by repeating the infection within a limited interval of time. This advice has the recommendation of being an imitation of the natural course of events consequent on tick infestation. If the ticks come, they may be relied upon to perform the reinoculation on their own account. It may be questioned, however, whether it is advisable to inoculate all animals until the closer approach of the ticks. In view of the rapidity with which the immunity can be produced, the inocuLation of the older cattle might be advantageously deferred until actually nece.ssarv, the operation being restricted in the meantime to the young stock. In this way there will be avoided the fatality attendant on inocu- lation, which mostly occurs in adult cattle. The present generation of old cattle might never need to be inoculated, but we should see to it that our future herds consist of highly-protected animals. By commencing as soon as possible, we shall gain the time necessary to properly immunise the cattle, and the advantage of being able to conduct our operations with a calmness and deliberation which will be impossible after the actual warfare begins. The total outcome of the above considerations, as to the manner in which we should bring our forces to bear to restrict the consequences of tick invasion, is to the following effect :—-AV^e should ener- getically maintain our border defences, and we should set about rendering our internal position as secure as possible by inoculation and reinoculation of our cattle. The young stock should be inoculated at once, and the old stock later on if necessary. The immunity conferred by the first inoculation should be supplemented by systematic reinoculation according to some definite plan, until the arrival of the ticks makes it no longer necessary. This, or something like this, must be our plan if we are to avoid the disaster which has befallen our Queensland neighbours. Sydney, December 29th, 1898. (Signed) DRANK TIDSAVELL. LIST](https://iiif.wellcomecollection.org/image/b28036116_0017.jp2/full/800%2C/0/default.jpg)
