PULLORUM DISEASE 7 



36. What is the intradermal, pullorin, or "wattle" test? This test consists 

 of injecting a biological preparation into the skin of the wattle. If a swelling 

 appears at the point of injection within a certain limit of time, the bird is regarded 

 as infected. 



37. Is the intradermal test reliable in eradicating infection from a flock? 



Leading investigators believe that the test in its present state is not so reliable 

 as other tests which are employed for eradication of the disease. 



38. What is the macroscopic tube agglutination test? In general this test 

 consists of the following steps: all birds are legbanded; a small amount of blood 

 is taken from the bird and the sample labeled with the legband number; a small 

 portion of serum is removed from the blood sample to a tube containing turbid 

 test fluid; the serum and test fluid are thoroughly mixed; the mixture is incubated 

 for 24 hours or longer at body temperature; and the results are recorded at the 

 end of the incubation period. A test is regarded as positive when a deposit has 

 formed in the bottom of the tube leaving the test fluid partially or completely 

 clear, and upon shaking of the tube the deposit breaks up into fine clumps. In 

 a negative test the turbidit}' of the mixture is not changed. All birds whose 

 samples react positively are reported as reactors or "carriers." 



39. What is the rapid serum agglutination test? This test is a modification 

 of the tube agglutination test. A small amount of serum taken from the blood 

 sample is placed on a glass plate. To this serum is added a small amount of 

 test fluid whose turbidity is far greater than that of the test fluid used for the 

 tube method. The serum and test fluid are mixed by stirring and after a few 

 minutes the result of the test is recorded. A test is positive when definite white 

 clumps form in the mixture of serum and test fluid. In a negative test the 

 mixture remains uniformly turbid. 



40. What is the whole blood agglutination test? The whole blood agglutina- 

 tion test consists of mixing whole fresh blood or whole dry blood with a stained 

 test fluid which is quite similar to that employed in the rapid serum method. 

 The results are recorded within a few minutes after the blood and test fluid are 

 mixed. A positive test is indicated by definite clumps floating in the mixture. 

 A negative test shows no cluni.ping. This test is used on the premises, usually in 

 the poultry house, and tested birds are retained in trapnests or improvised re- 

 tention coops until the results of the test are recorded. This makes it possible 

 to remove positive birds from the flock immediately. 



41. Have any of these tests been adopted as standard? At the present time, 

 the macroscopic tube agglutination test is regarded as the standard test for de- 

 tecting puUorum disease carriers. All three tests are recognized as ofificial tests 

 in the National Poultry Improvement Plan. However, for official certification 

 of flocks as free of pullorum disease, only the macroscopic tube agglutination 

 test should be accepted. 



42. Has a test been developed which has proved practical and reliable in the 

 hands of poultrymen? At the present time, no test for pullorum disease eradica- 

 tion is recognized as reliable and effective when placed in the hands of poultry- 

 men or persons not properly trained. The different tests are of such a nature 

 that they require thorough knowledge of the biological sciences in order to obtain 

 most expeditious and successful results in eradication of the disease. The results 

 of a test must be judged by the quality of the operator and the methods employed. 



