Conto,gious PLeuro- Pneumonia of Cattle. 19^3 



Compared with the complement fixation test in contagious 

 pleuro-pneumonia, the agglutination test appears to possess a 

 reliability and accuracy in reaction which is at least equal to, if 

 not greater, than that of complement fixation. 



Agglutination reactions are not affected by the presence of 

 •conglutinin in bovine sera, whereas that same substance is always 

 liable to affect the result of complement fixation reactions, and 

 may be responsible for a large number of false reactions. 



To prevent the action of conglutinin interfering with the ac- 

 curacy of the complement fixation test, an exceedingly intricate 

 and laborious technique has to be followed in each detail by the 

 operator. In these successive manipulations the possibility of 

 personal error on the part of the operator is very largely in- 

 >creased. By reason of its simpler technique the agglutination 

 test is not so liable to errors on the part of the worker. 



So far as it has been tested, the agglutination reaction in con- 

 tagious pleuro-pneumonia appears to provide us with a simple 

 .means for determining the presence of the disease, at least in 

 the acute form, in the living animal. Although the number of 

 positive sera tested is not very large, being only 18 from animals 

 in which the disease was acute, and five from animals in which 

 the disease was chronic, it would appear that the possibility of 

 error in acute cases of the disease is not very great owing to 

 ,the well marked differences in the end point values of sera taken 

 from acute cases, and those taken from animals free from the 

 disease. In the case of animals in which the disease is chronic, 

 diagnosis by means of the agglutination test does not appear to 

 be so certain, although there is still a fairly wide difference in 

 the end point values of such sera when compared with the values 

 of known negative sera. 



Application of the test to a large number of cases showing 

 chronic lesions is necessary to justify any firm conclusions on 

 this point. 



Specificity of the Complement Fixation and Agglu- 

 tination Reactions in Contagious Pleuro-Pneumonia. 



Since the publication of the results of the examination of 63 

 different serum samples for complement fixation and the sub- 

 sequent post-mortem findings when the animals were slaugh- 

 tered, experiments have been conducted to ascertain whether, 

 when a positive complement fixation result is obtained, the reac- 



