224 ANNUAL REPORT OF THE Off. Doc. 



measures than it is to cure the disease after is has developed. 

 Now, this is largely due to several things. For one thing, we do 

 not appreciate the dangers of the disease until the disease has ap- 

 peared. The disease itself is a tangible thing; the causes of the 

 disease are in most cases intangible — at least to the ordinary ob- 

 server. Our tendency to depend wholly upon curative measures in 

 combatting disease perhaps comes down to us from former times, 

 when the idea seemed to prevail that disease was something that 

 bad to be borne as a visitation, or as something that could not be 

 avoided — that must be taken as a matter of course. For many 

 years men gave all their attention to developing methods for curing 

 disease. The search for curative measures began with the ancients, 

 but it was not until 179G, when Jenner applied his discovery of 

 vaccination for smallpox, that the first advance was made in pre- 

 ventive medicine. But for a long time after that little attention 

 was paid to that side of the question. The invention and perfec- 

 tion of the microscope and the subsequent discovery of bacteria and 

 their relation to disease developed knowledge of value in the pre 

 vention as well as in the cure of disease. In fact, much of the 

 knowledge that has come to us today is more valuable in prevent- 

 ing or controlling disease than in curing it. There are some dis- 

 eases which we can prevent by preventive measures but which, 

 when developed, we cannot cure. We have also learned that drugs 

 are not the only means of combatting disease. Years of search 

 has failed to reveal a drug that will cure tuberculosis, but it has 

 been discovered that much headway can be made against this dis- 

 ease in man with pure air, sunlight, judicious exercise, and plenty 

 of wholesome, nourishing food. The sources of infection are better 

 known and the relation existing between the diseases of animals 

 and the dis'eases of man is receiving more consideration than for- 

 merly and there is great interest today all over the country in 

 milk inspection and in meat inspection. 



I said that many of our discoveries were of more value in the 

 prevention of diseases than in the cure of them. Koch was seeking 

 a cure for tuberculosis when he discovered tuberculin, and while 

 this substance was not a success as a curative agent, it has proven 

 most valuable in the control and eradication of tuberculosis in 

 herds of cattle. It is needless to speak here of its value in this 

 connection. It has been used for this purpose since 1890 and has 

 proven most reliable. Attacks are made from time to time on 

 the tuberculin test, but all the men who have had the greatest 

 experience with it are firmly convinced that it is absolutely reliable. 

 Experiments have been under way in the laboratory of the State 

 Livestock Sanitary Board for several years to develop a method of 

 vaccinating cattle that will render them resistant to tuberculosis 

 so that if they should be exposed to infection they will not contract 

 the disease. The great practical value of such a vaccine will be 

 apparent to everyone. These experiments have been so far suc- 

 cessful that a vaccine has been produced that will render the 

 treated animals proof against infection, and experiments now under 

 way are to determine how long the protection will last. 



The control of contagious diseases of aninuils is regulated by law 

 in many states. In Pennsylvania, as you know, the enforcement of 



