4 MASS. EXPERIMENT STATION BULLETIN 323 



It is apparent that the tube test is more sensitive than the whole blood test. 

 However, the authors state that a higher degree of correlation (98 percent) was 

 obtained between the standard tube, rapid serum, and whole blood tests in 

 several flocks subjected to repeated testing. They conclude that these observations 

 indicate that the whole blood test, in properly trained hands, constitutes the 

 simplest and most practical diagnostic procedure yet described for diagnosis 

 of pullorum disease. 



Torrey and Graham (8) investigated the problem of doubtful or partial reactors 

 to the whole blood test from the standpoint of pullorum-disease control. It was 

 observed that doubtful reactors were encountered more frequently in heavily 

 infected flocks. In repeated testing of 25 doubtful reactors with the whole blood 

 and tube methods, two types of reactors ("consistent" and "inconsistent") 

 were observed. Among the 25 birds tested, 21 (84 percent) were classified as 

 inconsistent with the whole blood test, and 19 (76 percent) with the tube test. 

 Necropsies of these birds revealed no gross characteristic lesions of the disease. 

 S. pullorum was isolated from one bird which was positive to the tube test, except 

 on one test which was doubtful. With the whole blood test, this bird was negative 

 on three tests, doubtful once, and positive twice. These results suggest that the 

 tube test is apparently more sensitive than the whole blood test. 



Higgins and Schroeder (5) tested 108 pullets with the tube test (diagnostic 

 dilution not stated) and with five stained antigens for the whole blood test. 

 The results show that the tube test was more sensitive than the whole blood test, 

 yet the authors conclude that very satisfactory agreement in the comparative 

 results was obtained, and that the whole blood test was equal in diagnostic value 

 to the tube agglutination method for detecting infected birds. 



An extensive investigation relative to the efficiency of the whole blood test 

 was made by Lubbehusen and Beach (6). Equal amounts of blood and antigen 

 were employed. It was observed that more satisfactory results were obtained 

 by mixing the blood and antigen without subsequent rotating of the plate; 

 incubating the tests for at least six to eight minutes at a constant temperature 

 of 80° C; and employing adequate light in order to insure accurate interpreta- 

 tion of the tests. 



Fourteen groups of birds on five farms were tested, representing a total of 

 91,449 test birds of which 42,214 were also tested with the tube test. It was 

 emphasized that the efficiency of the whole blood test should not be based on 

 decrease in percentage of reactors, but instead upon comparative results with the 

 tube test and bacteriological findings in birds necropsied. A total of 405 reactors 

 was detected by both methods, of which 217 yielded S. pullorum and 188 were 

 negative. The routine whole blood test detected 84 of the 217 infected birds, 

 giving a test efficiency of 38.71 percent. With the whole blood test conducted 

 under laboratory conditions, a test efficiency of 76.5 percent was obtained. The 

 routine tube test (1:25 dilution) detected 216 of the 217 infected birds with a 

 test efficiency of 99.53 percent. The routine tube test failed to detect one infected 

 bird which had given a strong positive reaction with the whole blood tesi . 



The authors state that repeated testing by the whole blood test, although 

 rendering the flock completely negative to that test, failed in each instance to 

 detect all infected fowls or all that would react to the tube test. The whole blood 

 test was more efficient when conducted in the laboratory than when conducted 

 in the field. The number of infected birds in the various flocks was reduced to 

 1 percent or less by repeated testing with the whole blood method. 



