NA TURE 



t'7 



THURSDAY, DECEMBER 13, 1877 



HYDROPHOBIA 



POPULAR alarm has of late been aroused by the 

 publication of an unusual number of cases of death 

 from this most terrible disease, and interest and hope have 

 been excited by the statement that, at last, a drug has 

 been found — curare — which does exert such an influence 

 that at least one case is said to have been rescued from 

 otherwise certain death. We propose to discuss briefly 

 in this article the chief points in the natural history of 

 hydrophobia, to examine what light, if any, science has 

 thrown upon its nature, and to inquire what reasons there 

 are for believing in the alleged efficacy of drugs in its 

 treatment. 



Hydrophobia is a disease which never occurs spon- 

 taneously in man, being invariably communicated to him 

 by the bite of some animal affected with it — commonly by 

 the dog, more rarely the cat, more rarely still the fox and 

 wolf. The bite induces the disease by permitting the 

 absorption of the saliva of the diseased animal, the peculiar 

 poison or '^ inateries tnorbi" of the disease being con- 

 tained in the saliva. Inasmuch, then, as man only 

 becomes affected with hydrophobia through the inter- 

 mediation of the lower animals, it will be necessary to 

 consider it, first of all, as it makes itself manifest in them. 



It has been, and still is, a subject of dispute amongst 

 veterinarians whether hydrophobia, or " rabies," was origi- 

 nated spontaneously in the dog. Avowedly the immense 

 majority of cases of the disease can be proved to have 

 been due to the bites of rabid animals; some cases do 

 occur, however, in which it is stated that there was no 

 possibility of contact with a diseased animal, and these 

 are held to prove the occasional spontaneous origin of the 

 disease. Now, whilst we are not prepared absolutely to 

 contradict such a surmise, and to allege that at no time, 

 and under no circumstances, hydrophobia originated 

 spontaneously, we do hold that there is no better evidence 

 of such a new origin now than there is of the spontaneous 

 generation of the poisons which induce small-pox, scarlet 

 fever, or measles. In the case of these diseases, as in 

 that of hydrophobia, it does sometimes happen that some 

 of the links in the chain of evidence are lost which are 

 required to prove the connection between one case of 

 disease and its precursor, but the exceptional cases do 

 not outweigh the immense mass of evidence which proves 

 that each of the diseases previously mentioned is as 

 certainly the offspring of a previous case as is each 

 animal or plant at present living the offspring of a pre- 

 existing parent organism. We shall then probably be 

 quite right in assuming that not only is it true of hydro- 

 phobia as it affects man, but of the disease as it is 

 manifest in all animals, that it is always due to the 

 inoculation of poison from a diseased into a healthy 

 organism. 



In commencing a description of hydrophobia we must 

 point out that whilst the disease is always more or less 

 prevalent, periods when it becomes much more frequent 

 occur from time to time. Within the present century, 

 especially between 1800 and 1830, several such outbreaks 

 occurred ; in this respect hydrophobia resembles other 

 Vou XVII,— No, 424 



diseases of the zymotic cla«s, which, though always more 

 or less prevalent, only occasionally prevail with epidemic 

 intensity. We must assume that at this period the cir- 

 cumstances which are required for the spread of the par- 

 ticular disease are specially favourable, though it is only 

 rarely that we can do more than surmise what these 

 special circumstances really are. 



In the dog, as indeed in all animals, there is a period 

 of latency, or as it is technically termed, of " incubation," 

 which intervenes between the inoculation of the poison 

 of hydrophobia and the development of any symptoms ; 

 this period varies remarkably : it may be as short as a 

 week, or as long as three months ; the greater number of 

 cases occurring, however, between the twentieth and 

 fiftieth days after the poisonous wound has been inflicted. 

 It must not be supposed that the bite of a rabid dog 

 always induces the disease in other dogs which it bites ; 

 a certain number of such bites prove abortive. Thus, 

 out of 131 dogs which had been bitten by, or inoculated 

 with, the virulent saliva of certainly rabid dogs, only sixty- 

 three fell victims. The failures in these cases are to be 

 explained in several ways. In some cases it is probable 

 that the saliva was not active, just as sometimes the 

 liquid from the vaccine vesicle, when fairly tested, is found 

 to be incapable of reproducing vaccinia ; in other cases 

 the poisonous saliva has doubtless been prevented from 

 penetrating the wound, having been retained by the hair 

 and cuticle of the bitten animal ; finally, in a third class 

 of cases, it must be assumed that the bitten animal did 

 not offer conditions required for the development of the 

 disease. A case is, indeed, recorded, on the best 

 authority, in which a pointer dog was caused to be bitten 

 on seventeen separate occasions by dogs affected with 

 rabies, without the disease being induced. 



The period of incubation having passed, the fii*st 

 symptoms of rabies usually consist in a change in the 

 temper of the dog, which becomes sullen and snappish, 

 and which often bites those around it, even without 

 any provocation. This prominence of the cerebral 

 symptoms in the early stages of hydrophobia in the dog 

 is very remarkable, and contrasts, as will be seen in the 

 sequel, with the phenomena of the disease in man. 

 It is evidenced not merely by the tendency to bile, but 

 by the whole changed aspect of the animal, which is now 

 observed to be obviously ailing. The appetite becomes 

 capricious, food often being refused, and all kinds of 

 rubbish swallowed, and often, though ^by no means 

 invariably, the dog utters dismal howls. It is in this 

 stage that the dog often wanders from home, and ap« 

 parently under the influence of maniacal excitement, 

 rushes on, biting all dogs which it meets, and often all 

 human beings who happen to come in its way. It is 

 to be noted that the dog does not exhibit any of the 

 dread of water which is so painfully evident in the disease 

 as it affects man ; this depends upon the fact that in the 

 dog there appears to be little, if any, tendency to spasm 

 of the muscles of deglutition. As the disease advances 

 palsy of the posterior extremities often occurs ; in other 

 cases a peculiar paralysis of the muscles connected with 

 the lower jaw sets in, so that the suffering animal ii 

 unable to utter any sound, and is said to be suffering from 

 " dumb-madness." Throughout the disease there is 

 usually an increased secretion of viscid saliva. The 



