RABIES 401 
should be free from exudates and the brain should appear perfectly normal, except that 
in rare cases there may be a slight injection of the blood vessels. The viscera are 
ordinarily normal in appearance, with possibly the exception of the liver, which we have 
frequently found to be deeply reddened, and the gastric mucosa, which not infrequently 
shows dark patches, indications of disintegrated hemorrhagic areas. 
Animals other than rabbits have been used and a number of other methods of inocula- 
tion have been proposed. 
Diagnosis by complement fixation method. Zell applied the com- 
plement fixation test to rabies, following the Wasserman technique. 
He used for an antigen a preparation of the salivary glands following 
the method of Poor and Steinhardt.* 
The serum of animals infected with street rabies was found by Zell 
to give a positive reaction, usually several days before clinical symp- 
toms appeared. He points out that by this method it is possible 
to make diagnoses without destroying the suspected animal and there- 
fore that it furnishes a test after the completion of the Pasteur treat- 
ment to determine whether or not immune bodies are present in the 
patient’s serum. In a later publication he recommends the use of 
the serum of the immunized animal as a prophylactic agent. He 
considers the serum from the immunized animal as efficient a prophy- 
lactic as tetanus antitoxin. 
The employment of sera has not been generally accepted as a means 
of diagnosis, but Zell’s report suggests that it may be of much value. 
Differential diagnosis. Rabies is to be differentiated from morbid 
conditions caused by certain parasites, paralytic forms of other 
diseases, and disorders manifested by nervous symptoms such as 
meningitis. Besson states that dogs are susceptible to Ps. pyo- 
cyaneus which develops symptoms resembling those of rabies. 
Prevention. The only means of preventing rabies after infection 
has taken place is to employ some one of the prophylactic treatments. 
The method formulated by Pasteur has proven to be most successful 
in the past. The serum immunizing method has been recently 
reported to be giving satisfactory results. 
“The Pasteur method of treatment is based upon the fact that the rabic virus in the 
spinal cord of rabbits loses strength at a fairly regular and even rate when the cord is 
removed from the body after death and carefully dried. In the preparation of material 
for the preventive treatment rabbits are inoculated with “fixed virus’—a term given 
*The method consists first, in the application of collodion sacs for the dialysis of 
glycerin. Second, the use of aspiration for obtaining the virus of rabies from the sub- 
maxillary glands of rabid dogs. This aspiration extract is virulent when filtered through 
the Berkefeld filter. 
