6 MASS. EXPERIMENT STATION BULLETIN 407 



LOSSES DUE TO PULLORUM DISEASE 



27. Do adult flocks suffer a mortality from this disease? Yes. Occasionally 

 a high mortality may be experienced when the disease develops into an acute form. 

 Carriers in general do not possess the disease resistance of normal birds; there- 

 fore, a higher mortality is observed among carriers' than among healthy individ- 

 uals. 



28. Is egg production affected? Yes. Investigations have shown that in- 

 fected birds do not lay as well as noninfected birds. This may be accounted for 

 by the diseased ovary, underdevelopment, and low disease resistance of the bird. 



29. Are fertility and hatchability affected? Yes. The percentages of fertility 

 and hatchability may be markedly reduced. ' 



30. Do chicks suffer a mortality? Frequently high mortalit\', sometimes as 

 high as 100 percent, is observed among infected chicks; infrequently little if any 

 mortality is observed. Overheating, chilling, overcrowding, and insanitary con- 

 ditions markedly influence the mortality rates. 



31. Do infected chicks mature normally? In severe outbreaks the normal 

 development is markedly aftected, as shown by a lack of uniformity of growth 

 and underdevelopment of birds. Chick flocks which have passed through an 

 outbreak of puUorum disease should not be retained for breeding or egg produc- 

 tion purposes. 



32. Does the presence of the disease affect the salability of eggs and stock? 

 Yes. The public has been and is being educated to buy only puUorum disease- 

 free stock. A buyer who has had the unfortunate experience of buying and losing 

 infected chicks will avoid repeating that experience if at all possible. A poultry- 

 man who has spent several years in developing a pullorum disease-free flock of 

 good breeding, and then unthinkingly or unknowingly introduces infection, will 

 suffer a great loss not only through the cost of eradicating the disease, but also 

 from reduced sales. 



CONTROL AND ERADICATION OF THE DISEASE 



33. Can the disease be eliminated by culling birds that lack vigor and vitality? 



No. "Carriers" of the disease are not always the poorest individuals in the flock. 

 Apparently normal, well-developed birds may be infected with the disease. 



34. Is incubator disinfection effective in eradicating the disease? Incubator 

 disinfection, while partially efi'ective in decreasing the spread of the disease in 

 the incubator, is not recommended as a means of controlling or eradicating the 

 disease because it is unable to destroy the organisms in the live chick. Infected 

 live chicks are spreaders of the disease, and complete control or eradication re- 

 quires the elimination of the spreader. Therefore, poultrymen who have outlined 

 an incubator disinfecting program with the intention of eradicating this disease, 

 can expect but one result — failure. Incubator disinfection should be regarded 

 as part of the general sanitary program and not as a disease eradication measure 

 in itself. 



35. How may carriers of this disease be detected? Infected birds may be 

 detected by the following tests: Intradermal test; macroscopic tube agglutination 

 test; rapid serum agglutination test; and whole blood agglutination test. 



