ISO ANNUAL RErOUT OF THE Off. Doe. 



symptom of the disease is expressed ii) Ihe term hydrophobia, and as 

 this symptom is not seen in animals, but in men, tlie appropriateness 

 of the term of tlie disease in man it at once apparent. 



Late in the eighteenth century, a highly acute and fatal disease 

 among dogs of Alassachusetts, near Boston, was recognized as rabies, 

 and before the close of that century, rabies was also recognized in 

 Pennsylvania. Since then it has been a matter of interest to note the 

 spread of the disease from the East to the West, which has been most 

 rapid during the last two decades, and the disease is now known to 

 exist in every state in the Union. Jn the Eastern states, particu- 

 larly New York and Pennsylvania, the disease has taken the pro- 

 portions of alarming epizootics within the past two years. 



Infection, under natural conditions, usually occurs following the 

 bite of an infected animal, the saliva containing the specific cause 

 or virus. Experimental transmission may be successfully accom- 

 plished by the injection of the portion of the brain tissue, spinal 

 cord, saliva, lachrymal secretion, pancreatic secretion or milk of an 

 animal with rabies. From the results of the inoculation of such ma- 

 terial, it has been shown that the virus is present in the brain and 

 spinal cord in its purest form and more constant in those tissues 

 than in the saliva or the other secretions. Accidental inoculation 

 with the subsequent development of the disease may follow the pene- 

 tration of slight and superficial wounds with saliva, etc., containing 

 the virus. Symptoms do not immediately follow the bite of a rabid 

 animal or injection of virus, but as in all infectious diseases, par- 

 ticularly those caused by protozoa, there is a period during which 

 nothing unusual is observed. This period of incubation, i. e., from 

 the time of infection to the beginning of symptoms, varies in the 

 different animals, depending upon the virulence of the virus, dose, 

 seat of inoculation and susceptibility of the victim. The symptoms 

 in the majority of cases are slow in developing, and as a rule an 

 animal when attracting attention has shown symptoms for many 

 hours, and not infrequently for a day or two. In that infected ani- 

 mals may show symptoms of the disease one or two days before the 

 symptoms attract attention, the question naturally arises, how long 

 before actual or noticeable symptions is it x>ossible for an animal 

 developing rabies to transmit the disease by means of a bite or other- 

 wise? Nocard and Eoux have both shown by experiment that the 

 saliva of a dog is infectious at least three days before the dog shows 

 symptoms of rabies, while in experiments conducted by the Athens 

 (Greece) Pasteur Institute, the virus was demonstrated in the saliva 

 eight days before the dog showed signs of the diseased This con- 

 clusively demonstrates that the saliva may carry the cause of rabies, 

 and that the presence of the virus may be demonstrated in the saliva 

 before the animal shows premonitory or actual symptoms. 



In establishing a diagnosis, the history, symptoms, gross autopsy 

 findings and laboratory examination are all of importance, but are 

 not all absolutely necessary in any one case, as at times a clear his- 

 tory of the animal having been bitten some weeks previous by a 

 rabid animal, and subsequent development of the characteristic symp- 

 toms following a period of incubation, may be sufficient for an ac- 

 curate diagnosis. Then again, the symptoms and gross autopsy find- 

 ings, without any history may be conclusive enough to suggest the 



