414 Hydrophobia, Lyssa, or Rabies 



tomed the animal first to them and then to stronger and 

 stronger ones until immunity was established. 



For the treatment of infected cases exactly the same method 

 is followed as for the production of immunity. Indeed, the 

 treatment of a patient bitten by a rabid animal is simply the 

 production of immunity during the prolonged incubation 

 period of the affection, so that the disease may not develop. 

 The patient, to be successfully treated, must come under 

 observation early. 



Method. To protect human beings from the development 

 of hydrophobia after they have been bitten by rabid animals, 

 it is necessary to use material of standard or known virulence. 

 This can be prepared, according to the directions of Hogyes,* 

 by the passage of virus from a rabid animal through from 

 21 to 30 rabbits. For this purpose some of the hippocampal 

 tissue of the dog is made into an emulsion with sterile salt 

 solution and injected subcutaneously into a rabbit. As soon 

 as this animal dies, its spinal cord is removed, a similar emul- 

 sion made with a fragment of it, and a second rabbit inoculated, 

 and so on through the series until a standard virulence is 

 attained and the virus is said to be " fixed." It has a much 

 higher degree of virulence than the " street virus " taken from 

 the rabid dog, but its virulence does not vary. In most 

 laboratories the "fixed virus" is obtained from other labora- 

 tories and kept passing through rabbits. In this manner 

 uniformity of dosage and virulence is most easily main- 

 tained. 



The technic of obtaining the rabbit's cord given by Oshidaf 

 is the one now generally employed. As given by Stimson, J it 

 is performed at the Hygienic Laboratory as follows: "The 

 rabbit, when completely paralyzed, is killed with chloroform 

 and nailed to a board, back uppermost, and thoroughly 

 wetted down with an aseptic solution (i per cent, trikresol). 

 An incision is made through the skin from the forehead nearly 

 to the tail and the skin laid back on each side, the ears 

 being cut close to the head. An area i inch wide is seared 

 with a hot iron around the occiput and nuchal region and ear 

 openings. The skin is then transversely divided in the center 



* See Kraus and Levaditi, "Handbuch der Immunitatsforschung," i. 

 t "Centralbl. f. Bakt. u. Parasitenk.," 1901, xxix, Orig., 988. 

 t" Facts and Problems of Rabies," Hygienic Laboratory Bulletin, 

 No. 65, June, 1910, Washington, D. C. 



