The results arrived at in this volume may be briefly summarised as follows : (1) That leprosy has greatly increased during the last half century, and that it is prevalent in many places where it was formerly unknown.
(2.) That whilst the opinion of medical authorities and experts varies considerably on the subject of the contagiousness of leprosy, the preponderance of authority is in favour of the theory that it is not contagious in the ordinary sense of the term, but is communicable by means of a cut, sore, or abraded surface; and this view is confirmed by my own personal investigations.
(3.) That other alleged factors such as malaria, a fish diet, syphilitic cachexia, heredity, and insanitation are admittedly unequal to explain the rapid growth of the disease in certain of our crown colonies and dependencies, as well as in other countries.
(4.) That on one point there is much agreement and hardly any dissent, namely, the inoculability of leprosy; and that the view of leprosy as an inoculable disease, while it is most clear to those who take the malady to be due to a bacillus, is older than the bacteriological evidence, and is not dependent thereon.
(5) That the most frequent opportunities of inoculating the virus of leprosy are afforded in the practice of inoculating vaccine, which is the only inoculation that is habitual and imposed by law; and that the evidence here adduced is calculated to show that vaccination is a true cause of the diffusion of leprosy.
(6.) That the official information, collected by interrogatores and otherwise, has not been hitherto of a kind to show how far vaccination has determined the amount of leprosy in recent times; and that any interrogatories that may be sent out in future should not be limited to ascertaining the effects, as regards leprosy, of hypothetically "pure" lymph. When on very rare occasions interrogatories have been submitted, they have been framed to ascertain the results of a purely hypothetical system of vaccination which is not anywhere discoverable in practice, and alleged to be unattainable (i.e., with pure lymph, and free from hereditary taints, and the replies are therefore futile and misleading.
(7.) That with the exception of two groups of cases those adduced by Dr. Roger S. Chew, of Calcutta, and Dr. S. P. Impey, of Robben Islandthose reported in this volume have not been the result of special investigation, but have cropped up accidentally in the course of medical practice, and in some instances have been published by practitioners with apologies to the profession for presenting such unwelcome disclosures.
(8.) That the increase of leprosy in the Sandwich Islands, the West Indies, the United States of Colombia, British Guiana, South Africa, and New Caledonia, has followed pari passu with the introduction and extension of vaccination, which in nearly all these places, without previous inquiry or demand from the inhabitants, has been made compulsory.
(9.) That as leprosy is a disease of slow incubation, often taking years to declare itself, and in its incipient stages can be detected only by practitioners of large experience, it follows that, in countries where leprosy exists, there is great danger of extending the disease by arm-to-arm vaccination.
(10) Leprosy being one of the most loathsome diseases to which the human race is subject, and being practically incurable, it behoves all interested in the public well-being to do their best to prevent its diffusion, and, as a means thereto, to discourage the practice of vaccination on that ground, if on no other.