PULLORUM DISEASE 17 



45. — Are non-reacting infected birds considered as spreaders? In- 

 vestigators have found the causative organism in eggs laid by such birds. The 

 organism has also been isolated from the ovary and other organs on necropsy. 

 Fortunately such birds are rare, as shown in flocks which are tested annually. 



46. — Are all reactors infected with the organism? Reacting birds are 

 observed in which no gross signs of the disease can be found. Few such birds are 

 found infected on bacteriological examination. A plausible explanation for 

 failure to isolate the organism from some reacting birds is that such liirds either 

 have been infected recently or the organism has been eliminated recently. How- 

 ever, it must also be recognized that the methods of examination have their 

 limitations. 



47. — Do all reactors lay infective eggs? No. If the infection is locahzed 

 in those parts of the body wliii'h have no direct relation or communication with 

 the oviduct, the organism is not eliminated through the egg. Furthermore, 

 not all eggs laid by an infected bird contain the organism. 



48. — Should fresh eggs from infected or untested flocks be fed to non- 

 infected stock? No. Investigations have shown that birds may be infected 

 when fresh eggs laid by infected birds are fed. 



49. — Why do negatively reacting birds suddenly become positive 

 reactors? Non-reacting birds that suddenly react positively, in all probability 

 have been infected recently. Artificial infection has shown that birds may first 

 react between the fourth and seventh day after the first exposure. The avenue 

 of infection, the size of dose, the ability of the organism to infect the bird, the 

 i-esistance of the bird, and the ability of the bird to produce antibodies are fac- 

 tors that determine the reaction of the bird. 



50. — Should the flock be tested annually? Yes. Poultrymen who use 

 part or all of their flocks for breeding purposes should test all birds on the premises 

 each year. The test is a means of detecting infected birds. It does not assure 

 the owner that once his flock is free of infection it will remain free. Flocks do 

 become re-infected, and through annual testing the infection is detected and 

 eliminated before it has an opportunity to cause great losses. Therefore, annual 

 testing is necessary to determine, from year to year, the status of the flock in 

 regard to this disease. 



51. — At what age may birds be tested? Reactors have been detected 

 among chicks seven days of age or older. However, infected chicks do not all 

 react at this age period. Birds tested between four and twelve weeks of age will 

 show a larger percentage of reactors than if tested at a younger age. On the other 

 hand, some young birds detected as reactors may become negative towards 

 maturity. Since this disease will be disseminated as long as infected birds are 

 present, the purpose should be to eliminate the majority if not all of the infected 

 birds at the earliest practical age. Birds three to four months of age may -be tested 

 successfully. 



52. — Should birds attain egg production before they are tested? 



Since the majority of infected birds can be detected before they attain egg 

 production, it is advisable from an eradication point of view to eliminate the 

 infected birds before they attain egg production in order to prevent the spread 

 of the disease through the eating of infective eggs laid by diseased birds. Further- 

 more, elimination of infected birds at an early age will also prevent dissemina- 

 tion by other means common in a diseased flock. 



