4 MASS. EXPERIMENT STATION BULLETIN 407 



10. Through what avenues may birds become infected? Birds have been 

 infected by way of the digestive and respiratory tracts, eyes, abrasions in the 

 skin, and cloaca. 



11. How may infection be introduced into an adult flock? The disease may 

 be introduced into an adult flock through buying infected stock, returning birds 

 from shows or contests, using contaminated buildings and ranges, using equip- 

 ment (bird and egg crates, feed sacks, etc.) that may have been contaminated 

 elsewhere, feeding infective eggs, and feeding garbage which might contain infec- 

 tive eggs or offal of infected birds.- 



12. Can adult birds contract the disease by eating fresh eggs laid by in- 

 fected hens? Yes. Investigations have shown that birds may contract the 

 disease by eating infective fresh eggs. In some flocks birds have formed a habit 

 of egg-eating, perhaps as a result of birds laj'ing the eggs on the floor or dropping 

 board. At present the most important means of spread among adult flocks 

 appears to be through eating infective fresh eggs. 



13. Can the disease be transmitted through the egg? Yes. Infective eggs 

 used for hatching purposes transmit the disease to the chicks. Feeding of fresh 

 infective eggs to chicks or mature birds will infect them. Feeding of discarded 

 infective incubator eggs to chicks or mature birds will readily infect them. 



14. How does the disease affect young chicks? The disease may manifest 

 itself within a few days after hatching. The following symptoms may be ob- 

 served: depressed vigor, loss of appetite, a tendency to remain under the hover, 

 frequent cheeping, droopy wings, shortened bodies, pasting of the vent with 

 chalky excreta, marked depression and exhaustion followed by death. These 

 symptoms are neither characteristic nor specific for pullorum disease alone, since 

 they may be observed in other health disturbances of chicks. The mortality 

 rate may vary from low to as high as 100 percent. Losses may be observed 

 within two or three days after hatching and may continue until the chicks are 

 three weeks of age or older. The greatest losses usually occur during the second 

 week of chickhood. The onset and severity of the disease depend upon the 

 amount of infection in the body, the ability of the organism to produce the 

 disease, the resistance of the chick, and the care given by the poultryman. In 

 some cases diseased chicks show little or no evidence of infection, while in other 

 cases all the possible manifestations of the disease are found. 



15. Can the disease in young chicks be accurately diagnosed without bac- 

 teriological examination? No. The symptoms and lesions are not specific of 

 pullorum disease alone. Diagnosticians with considerable experience frequently 

 may arrive at a tentative diagnosis of pullorum infection based on symptoms 

 and lesions, which is later confirmed by bacteriological findings. As a routine 

 procedure it appears necessary that all diagnoses of pullorum disease should be 

 based on bacteriological evidence. 



16. Why is an accurate diagnosis important? An accurate diagnosis will make 

 it possible for the owner to follow proper eradication plans. An inaccurate 

 diagnosis of pullorum disease may be responsible for unwarranted efforts and 

 expenditures or cause further dissemination of the disease and delay eradication. 

 One must recognize that for infected and noninfected flocks the plans of manage- 

 ment should not be the same in order to obtain efi'ective and profitable results. 



