7b THE PROBLEM OF HORSE SICKNESS. 



sorry to say that in none of these modern drugs has a cure yet 

 been found. 



Another method of attacking the causal organism in the 

 system is by means of the serum therapy. Immunity in an 

 infectious disease is usually accompanied by the production of 

 specific anti-bodies usually found in the blood-stream. By 

 means of hyperimmunisation an increase of immune bodies in 

 the blood-stream can be effected. They are present in the 

 serum withdrawn from such an animal, which, properly pre- 

 served, represents the remedy. These anti-bodies are either 

 anti-toxic — z'ic. they neutralise the toxin produced by the 

 organism — or anti-infectious — z'ic, they kill the organisms. Also 

 in horse-sickness we can produce an anti-serum, notwithstanding 

 that the micro-organisms is ultravisible and not cultivable. It 

 is done simply by transfusing the blood of a sick animal which 

 contains the virus into an immune animal, and in due time, 

 about 14 davs later, the serum of the immune animal is ready 

 for use. That such a serum is powerful is shown by the fact 

 that the addition of serum to a quantity of corresponding virus 

 renders this virus harmless ; it is also capable of arresting the 

 evolution of horse-sickness in a horse which has been injected 

 with a strain of less virulency than that which served to produce 

 the serum, and is even so powerful as to turn a reaction pro- 

 duced by such an attenuated virus to a recovery in a great 

 number of cases. The activity of the serum on the fully- 

 developed disease, as recognised bv the layman, even when due 

 to a weak virus, is almost nil. The lesions produced by the 

 horse-sickness organism seems to be irreparable after they have 

 reached a certain stage. Serum is. therefore, of but little use 

 from a curative point of view. An attemi^t for the solution of 

 the problem must be directed towards the prevention of the 

 disease. This can be undertaken in two different wavs. The 

 one, the radical one. which goes at the root of the evil, means 

 the eradication of the disease ; the other one, of a temporary 

 character, means the protection of the animals agfainst the 

 attacking transmitting hosts, or bv means of immunity against 

 the causal organisms injected by the transmitting hosts. 



The eradication of the disease would be the ideal solution 

 of the problem. Can it be achieved? 



In the chain of events which lead to horse-sickness there 

 are two links, which, when they could be broken, would lead to 

 this great object. The one is the destruction of the virus 

 reservoir (the virus carrier), the other of the virus transmitting 

 insect. Since the virus carrier is not as yet known, further 

 suggestions are out of place. The question is nevertheless of 

 theoretical importance. The destruction of the transmitting 

 agency would be possible, although we do not as yet know it 

 exactly. In the past we have not pressed home this point as 

 much as it deserved, simplv because we did not, and do not, 

 know the actual insect. We do not know its whereabouts, its 



