JnlyT, 1887] 



NA TURE 



233 



rabies, and, with rare exceptions, all of the second set will so 

 die. 



It may, hence, be deemed certain that M. Pasteur has dis- 

 covered a method of protection from rabies comparable with that 

 which vaccination affords against infection from small-pox. It 

 would be difficult to over-estimate the importance of the dis- 

 covery, whether for its practical utility or for its application in 

 general pathology. It shows a new method of inoculation, or, 

 as M. Pasteur sometimes calls it, of vaccination, the like of 

 which it may become possible to employ for protection of both 

 men and domestic animals against others of the most intense 

 kinds of virus. 



The duration of the immunity from rabies which is conferred 

 by inoculation is not yet determined ; but during the two years 

 that have passed since it was first proved there have been no 

 indications of its being limited. 



The evidence that an animal may thus, by progressive inocula- 

 tions, be protected from rabies suggested to M. Pasteur that if 

 any animal or any person, though unprotected, were bitten by a 

 rabid dog, the fatal influence of the virus might be prevented ^ 

 by a timely series of similar progressive inoculations. He has 

 accordingly, in the institution established by him in Paris, thus 

 inoculated a very large number of persons believed to have been 

 bitten by rabid animals ; and we have endeavoured to ascertain 

 with what amount of success he has done so. 



The question might be answered with numerical accuracy if it 

 were possible to ascertain the relative numbers of cases of hydro- 

 phobia occurring among persons of whom, after being similarly 

 bitten by really rabid animals, some were and some were not 

 inoculated. But an accurate numerical estimate of this kind is 

 not possible. For 



(1) It is often difficult, and sometimes impossible, to ascertain 

 whether the animals by which people were bitten, and which 

 were believed to be rabid, were really so. They may have 

 escaped, or may have been killed at once, or may have been 

 observed by none but persons quite incompetent to judge of their 

 condition. 



(2) The probability of hydrophobia occurring in persons bitten 

 by dogs that were certainly rabid depends very much on the 

 number and character of the bites ; whether they are on the 

 face or hands or other naked parts ; or, if they have been in- 

 flicted on parts covered with clothes, their effects may depend on 

 the texture of the clothes, and the extent to which they are torn ; 

 and, in all cases, the amount of bleeding from the wounds may 

 affect the probability of absorption of virus. 



(3) In all cases, the probability of infection from bites may be 

 affected by speedy cauterizing or excision of the wounded parts, 

 or by various washings or other methods of treatment. 



(4) The bites of different species of animals, and even of dif- 

 ferent dogs, are, probably, for various reasons, unequally danger- 

 ous. Last year, at Deptford, five children were bitten by one 

 dog and all died ; in other cases, a dog is said to have bitten 

 twenty persons, of whom only one died. And it is certain that 

 the bites of rabid wolves, and probable that those of rabid cats, 

 are far more dangerous than those of rabid dogs. 



The amount of uncertainty due to these and other causes may 

 be expressed by the fact that the percentage of deaths among 

 persons who have been bitten by dogs believed to have been 

 rabid, and who have not been inoculated or otherwise treated, 

 has been, in some groups of cases, estimated at the rate of only 

 5 per cent. , in others at 60 per cent. , and in others at various inter- 

 mediate rates. The mortality from the bites of rabid wolves, 

 also, has been, in different instances, estimated at from 30 to 95 

 per cent. 



To ascertain, as far as possible, the influence of these sources 

 of fallacy in cases inoculated by M. Pasteur, the members of the 

 Committee who went to Paris requested him to enable them to 

 investigate, by personal inquiry, the cases of some of those who 

 had been treated by him. He at once, and very courteously, 

 assented, and the names of 90 persons were taken from his note- 

 books. No selection was made, except that the names were 

 taken from his earliest cases, in which the periods since inocula- 

 tion were longest, and from those of persons living within reach 

 in Paris, Lyons, and St. Etienne. 



_ ' The terms referring to "preventive" trcitment will be used for that de- 

 signed to prevent the occurrence of the disease in one already infected ; 

 t^osc referring to " protective" treatment for that designed to protect a man 

 or an animal from the risk of becoming infected. And it may be well to state 

 that, though the usual custom is followed of employing the name of " hydro- 

 phobia " for the disease in men, and of " rabies " for that in animals, they 

 are really the same disea^s. 



The notes made on the spot concerning all these cases are 

 given in the Appendix, and they include, as far as was possible, 

 the evidence whether the dogs deemed rabid were really 

 so, the situation and kind of bites, the immediate treatment of 

 them, the statements of medical practitioners and veterinary 

 surgeons to whom any useful facts were known.* 



Among the 90 cases there were 24 in which the patients were 

 bitten on naked parts by undoubtedly rabid dogs, and the wounds 

 were not cauterized or treated in any way likely to have pre- 

 vented the action of the virus ; there were 31 in which there was 

 no clear evidence that the dog was rabid ; others in which the 

 bite, though inflicted by undoubtedly rabid animals, having been 

 through clothes, may thus have been rendered harmless. Among 

 these, therefore, it is probable that, even if they had not been 

 inoculated, few would have died. Still, the results observed in 

 the total of the 90 cases may justly be compared with those ob- 

 served in large numbers of cases similar to these as regards the 

 uncertainties of infection, but not inoculated. The estimates 

 published as to the mortalities in such unassorted cases are, as we 

 have said, widely various. We believe that among the 90 per- 

 sons, including the 24 bitten on naked parts, not less than eight 

 would have died if they had not been inoculated. At the time 

 of the inquiry, in April and May 1886, which was at least 

 eighteen weeks since the treatment of the bites, not one had 

 shown any signs of hydrophobia, nor has any one of them since 

 died of that disease. 



Thus, the personal investigation of M. Pasteur's cases by 

 members of the Committee was, so far as it went, entirely satis- 

 factory, and convinced them of the perfect accuracy of his 

 records. 



After the first few months in which M. Pasteur practised his 

 treatment, he was occasionally obliged, in order to quiet fears, 

 to inoculate persons who believed that they had been bitten by 

 rabid animals, but could give no satisfactory evidence of it. It 

 might, therefore, be deemed unjust to estimate the total value 

 of his treatment in the whole of his cases as being more than is 

 represented by the difference between the rate of mortality ob- 

 served in them and the lowest rate observed in any large number 

 of cases not inoculated. This lowest rate may be taken at 5 per 

 cent. Between October 1885 and the end of December 1886, 

 M. Pasteur inoculated 2682 persons, including 127 who went 

 from this country. Of the whole number, at the rate of 5 per 

 cent., at least 130 should have died. At the end of 1886, the 

 number of deaths stated by M. Vulpian, speaking for M. Pasteur, 

 was 31, including 7 bitten by wolves, in three of whom the 

 symptoms of hydrophobia appeared while they were under treat- 

 ment, and before the series of inoculations were complete. 

 Since 1886 two more of those inoculated in that year have 

 died of hydrophobia. 



The number of deaths assigned by those who have sought to 

 prove the inutility of M. Pasteur's treatment i.s, as nearly as we 

 can ascertain, 40 out of the 2682 ; and in this number are in- 

 cluded the seven deaths from bites by wolves, and probably not 

 less than four in which it is doubtful whether the deaths were 

 due to hydrophobia or to some other disease. Making fair 

 allowance for uncertainties and for questions which cannot now 

 be settled, we believe it sure that, excluding the deaths after 

 bites by rabid wolves, the proportion of deaths in the 2634 per- 

 sons bitten by other animals was between i and i"2 per cent, 

 a proportion far lower than the lowest estimated among those 

 not submitted to M. Pasteur's treatment, and showing, even on 

 this lowest estimate, the saving of not less than lOO lives. 



The evidence of the utility of M. Pasteur's method, indicated 

 by these numbers, is confirmed by the results obtained in certain 

 groups of his cases. 



Of 233 persons bitten by animals in which rabies was proved, 

 either by inoculation from their spinal cords, or by the occurrence 

 of rabies in other animals or in persons bitten by them, only 4 

 died. Without inoculation it would have been expected that at 

 least 40 would have died. 



Among 186 bitten on the head or face by animals in which 

 rabies was proved by experimental inoculations, or was observed 

 by veterinary surgeons, only 9 died, instead of at least 40. 



And of 48 bitten by rabid wolves only 9 died ; while, without 

 the preventive treatment, the mortality, according to the most 

 probable estimates yet made, would have been nearly 30. 



• The Committee are much indebted to M. Arloing, Director of the 

 Veterinary School at Lyons : M. Savary. Veterinary Surgeon at Brie-Comte- 

 Robert ; and M. Charlols, Veterinary Surgeon at St. Etienne, for assistance 

 in their inquiries. 



