ERADICATION OF PULLORUM DISEASE 1931-32 19 



Conclusions 



1. Fresh eggs, laid by reacting hens, may produce pullorum disease when 

 fed to non-infected hens and pullets. 



2. It is probable that younger birds may contract the disease more readily 

 through eating infective eggs than older birds. 



3. The habit of "egg-eating" or "egg-picking," in an infected flock, should 

 be regarded as a hazard to an eradication program for such a flock. 



EXPOSURE OF PULLORUM DISEASE-FREE BIRDS 



TO SOIL AND LITTER CONTAMINATED WITH FECES 



FROM POSITIVE REACTING BIRDS 



The object of the experiment reported in this paper was to determine whether 

 pullorum disease-free birds could be infected through exposure to soil and litter 

 contaminated -^vith feces from positive reacting birds. 



From the results reported bj^ several investigators, it can be concluded def- 

 initely that pullorum disease does spread through the association of infected 

 with non-infected, sexually mature birds. Rettger, Kirkpatrick, and Stonebum 

 (74) have reported cross-infection when 7 non-infected hens were penned with 7 

 infected hens for a period of 2 years. To determine whether a bird became in- 

 fected or not, all eggs laid by the negative birds were examined for S. pullorum. 

 By this method it was determined that 3 of the original non-infected hens had 

 become infected. The same authors also were able to infect non-infected hens by 

 sprinkling a broth culture of 5. pullorum on the litter two or three times a week. 

 Doyle (27) was unsuccessful in transmitting pullorum disease when 50 positive- 

 reacting hens were housed with 30 non-reacting hens for 1 year. Leynen (59) 

 concluded that the spread of pullorum disease through cohabitation does not 

 occur readily. Brunett (11, 14) after an ex-tensive study concluded that pullorum 

 disease spreads between mature birds but not to as great an extent as is generally 

 beheved. He was successful in demonstrating the spread of pullorum disease 

 both in the presence and absence of male birds. Edwards and Hull (31) con- 

 cluded that the transmission of pullorum disease may occur without the presence 

 of males. Kernkamp (55), from the results of two experiments, concluded that 

 pullorum disease spreads between sexually mature birds. In both of these ex- 

 periments, male birds were present in the pens. Warrack and Dalling (94, 95), 

 after a series of experiments, made the following conclusion: Transmission of 

 pullorum disease takes place among sexually mature birds and the smaller the 

 space in which birds are penned the greater the chance of transmission taking 

 place. Investigations at the CaUfomia (16) and Illinois (50) Agricultural Ex- 

 periment Stations have also shown the transmission of pullorum disease between 

 infected and non-infected adult birds. Kerr (56) reported the isolation of S. 

 pullorum from the feces of three adult hens by bacteriological methods. This is 

 the only reference noted in which S. pullorum has been isolated from the feces of 

 adult birds. 



Although Doyle (27) was unsuccessful in transmitting pullorum disease 

 through the association of infected and non-infected hens, he was successful in 

 transmitting the disease to day-old chicks housed with positive-reacting hens. 



Mathews (63) working with day-old chicks and infected hens failed to dem- 

 onstrate 5. pullorum in the feces of the infected hens. Fifty day-old chicks were 

 divided into three groups. Group I was fed chick feed containing 5 per cent of 

 fresh feces from 8 positive-reacting hens. Group II was brooded in a pen which 

 communicated with another pen in which there were 3 positive-reacting hens. 

 Chicks mingled with the hens freely. Group III was a control pen. At the end 

 of two to three weeks the chicks were killed and examined bacteriologically for 



