432 VACCINE VIRUS 



The thorough cauterization of the dog-bite wound with pure nitric 

 acid, as soon as possible after the bite, is imperative even when the Pas- 

 teur treatment can be given later. 



Smallpox. The etiology of this disease is very obscure, the virus 

 being grouped under the Chlamydozoa. Smallpox and vaccinia are 

 often classed as filterable viruses. Park, however, was unable to pass 

 the virus of vaccinia through a Berkefeld filter with 40 pounds pressure; 

 the failure may have been due to lack of sufficient dilution. They did 

 find that the virus would pass through the finest filter-paper. 



In 1892 Guarnieri noted cell inclusions in the cornea of rabbits inoculated with 

 smallpox and under the name Cytorrhyctes variola, Councilman has described what 

 he regards as a protozoon invading cell nuclei. Certainly ordinary bacteria are not 

 concerned in the etiology of smallpox. The virus is not only contained in the skin 

 lesions but also in nasal and buccal secretions, the disease being communicable 

 before the eruption appears. The period of incubation of variola vera is very con- 

 stantly twelve days, while that of variola inoculata (a method of prophylaxis by 

 inoculating discharges from a vesicle or pustule which preceded the present 

 method of vaccination) is eight days. Monkeys are quite susceptible to both small- 

 pox and vaccinia as is also true of corneal inoculations of rabbits. 



Cutaneously the rabbit shows a typical eruption after vaccination, 

 but does not show characteristic lesions after smallpox inoculation. 



It is usually accepted that vaccinia is simply a permanently modified smallpox 

 resulting from animal passage and it is stated that repeated passage of smallpox 

 virus through calves produces vaccine virus. Inoculation of calves with smallpox 

 virus is a most uncertain procedure and Park states that he has been unable to obtain 

 success after many such experiments. 



Of great practical importance is the differentiation of smallpox 

 and chicken-pox. In efficiently vaccinated persons the cutaneous in- 

 oculation of material from the suspicious vesicle will give rise to a skin 

 reaction similar to the Pirquet Tb. one, occurring within twenty-four 

 hours. If the vesicle were of chicken-pox no reaction occurs. Heating 

 the material to 6oC. for thirty minutes eliminates all danger and does 

 not interfere with the reaction. (Tieche.) 



Vaccinia. Vaccinia is a disease produced artificially by the injection 

 of vaccine virus obtained from the calf. The material for vaccine is 

 taken from vesicles about one week after the inoculation. The most 

 potent material is in the pulp at the base of the vesicle and not in the 

 lymph which exudes from the vesicle. The pulp is ground up and mixed 

 with an equal amount of glycerine, which acts not only as a preservative 

 but as a mild antiseptic for nonsporing bacteria. The calves are autop- 



