METHODS OF DIAGNOSIS 505 



Distinct agglutination with a 1 : 30 dilution of the serum in 

 half an hour may be taken as a positive reaction, sufficient for 

 diagnosis. The reaction is, however, usually given by much 

 higher dilutions, e.g., 1 : 500, and even higher. It is to be noted 

 that normal serum diluted 1 : 5 may produce some agglutination, 

 and this property is said to be destroyed at 55° C, whereas the 

 specific agglutinin is not affected. Some observers accordingly 

 recommend that, in applying the test, the serum ought to be first 

 heated to 55° C. As regards relation to prognosis, the observa- 

 tions of Birt and Lamb and of Bassett-Smith have given results 

 analogous to those obtained in typhoid (p. 374). 



The Commission found that vaccination with dead cultures 

 of the micrococcus confers a certain degree of protection amongst 

 those exposed to the disease. As a rule two injections were 

 made, 200-300 million cocci being the dose of the first injection, 

 and about 400 million the dose of the second. The use of vaccines 

 has also been carried out in the treatment of the disease, but 

 the observations are not sufficiently numerous to allow a definite 

 statement to be made as to its value. 



Methods of Diagnosis. — During life the readiest means of diagnosis is 

 supplied by the agglutinative test just described (for technique, vide 

 p. 116). 



Cultures are most easily obtained from the spleen either during life or 

 post mortem. Inoculate a number of agar tubes by successive strokes and 

 incubate at 37° C. Film preparations should also be made from the 

 spleen pulp and stained with carbol-thionin-blue or diluted carbol-fuchsin 

 (1 : 10). Cultures may sometimes be obtained from the blood by the 

 usual methods. 



Great care must be exercised in working with cultures of the 

 m. melitensis, as bacteriologists have become infected with the disease, 

 apparently from such sources, in an unusually high proportion of 

 instances as compared with other affections. 



