152 POULTRY DISEASES AND THEIR TREATMENT. 



The presence of these nodules on the epithelium of the head 

 is often (but apparently not always) accompanied with char- 

 acteristic roup lesions of the nasal cavities, mouth and throat. 

 As long as the disease is confined to the skin of the head the 

 general health of the bird does not seem to be affected. Recov- 

 ery may take place without treatment in from 10 to 20 days. 

 The nodules in such cases dry up and fall off. Usually, how- 

 ever, the disease is not self-limited, but advances. The eyes 

 may become closed so that the birds cannot see to eat. They get 

 poor and die from exhaustion. When the mucous membrane 

 of the mouth developes diphtheritic membranes death occurs 

 earlier than in other forms. 



Etiology. The lesions of this disease resemble the lesions of 

 roup and many of the same micro-organisms are found in the 

 two cases. The organisms isolated from the lesions of sore- 

 head include several bacteria, a coccidium, a yeast and several 

 moulds. The coccidium, one of the moulds, and one of the 

 bacteria have each been considered the- cause of the disease by 

 different workers. The real cause of the disease and its rela- 

 tion to roup must be determined by further investigations. The 

 following discussion of the etiology of sore-head is given by 

 Gary (Chicken-Pox or Sore Head in Poultry. Alabama Agric. 

 Expt. Stat. Bulletin 136) : 



"Transmission and Dissemination. It is evidently infec- 

 tious ; because the disease in all its forms, spreads rather rapidly 

 from one chicken or pigeon to another. Ward, Harrison and 

 others have transmitted, in some cases quite readily by carrying 

 small amount of diseased material (exudate and blood), from a 

 sore-head chicken to healthy chickens. It is also quite certain 

 that chicken pox and pigeon pox are identical or one and the 

 same disease." 



"Mosquitoes, gnat flies, chicken mites (ticks), chicken lice, 

 chicken foot mites {Sarcoptes mutans) and possibly cock-roaches 

 may sometimes be carriers of the real virus. It seems quite cer- 

 tain that mosquitoes can transmit the virus from water or some 

 other source, under certain conditions. Warm and wet weather 

 seem to increase the virulency of the virus and favor the rapid 

 transmission of the disease. It is not impossible that ants may 

 have a role to play in the transmission or cause of sore-head." 



"Pathological Ancttomy. On the skin the small, greasy-like 

 nodules, or hypertrophied nodules of the skin, contain epithelial 



