82 VACCINE AND SERUM THERAPY. 



is increased in virulence for rabbits. After a number of passages 

 through rabbits the virus finally can no longer be exalted in viru- 

 lence. This is then called the fixed virus, is usually obtained from 

 the cord and kills a rabbit in six to seven days. . This fixed virus 

 can, by drying, be gradually decreased in virulence so that after 

 fourteen days of drying it has lost all virulence for rabbits. To 

 immunize the individual, virus of low virulence is first injected, 

 after which inject ions are made with virus of greater virulence until 

 at the end of the treatment injections of cord which has dried only 

 from two to three days, are made. 



At the present time there are in the United States many so- 

 called ' 'Pasteur Departments" for immunization against rabies. The 

 particular technique employed in such departments varies in some 

 details, still the fundamental and essential principles are the same. 



In every case treated, an attempt is made to establish definitely 

 the diagnosis of rabies. Two methods are employed to accomplish 

 this: one is to examine for Negri bodies and the other is to make 

 inoculations into rabbits. For both of these methods it is es- 

 sential that the head of the rabid animal be preserved intact and 

 sent to the laboratory for diagnosis. It is therefore recommended 

 that rabid animals be killed by other methods than those which 

 mutilate the head. 



As soon as the diagnosis is established, or if this is impossible 

 because the animal cannot be found, the patient should submit to 

 treatment. This requires from two to four weeks and. consists 

 usually in daily injections of cord of hydrophobia rabbits, which 

 has been aseptically dried over caustic potash at a temperature of 

 about 23 C. for varying periods of time. After drying, a part of 

 the cord is suspended in bouillon to which either 0.25 per cent car- 

 bolic acid or glycerine has been added as a preservative. The in- 

 jections are made into the subcutaneous tissue and are usually not 

 followed by much disturbance. If there is an inflammatory reac- 

 tion, it is to be treated as any other cellulitis. During the treatment, 

 the patient may go about his work, his bowels should be kept open 

 and alcoholic excess avoided. Immunization is not fully attained 

 until about two weeks after the last injection of virus. 



Immunization is usually and preferably practiced at the hos- 

 pital of Pasteur departments. The New York City Department of 

 Health has also practised immunization by sending virus to physi- 



