RESPIRATORY DISEASES 147 



Chickenpox — Contagious Epithelioma 



This disease affects chickens, turkeys, pigeons 

 and geese. 



Cause. — Some investigators claim that it is due 

 to an ultra-microscopic virus (germ) and that the 

 same germ is also the cause of avian diphtheria, or 

 roup. (An ultra-microscopic germ is one that will 

 pass through the pores of porcelain filters and can- 

 not be seen with the microscope or grown in visi- 

 ble quantities upon culture media.) There are 

 just as many investigators who are certain that 

 their results show that the germ causing these 

 (pox and roup) are not the same, and that the 

 infection one time will not produce roup and at 

 another chickenpox (contagious epithelioma). Our 

 experiments do not lead us to the conclusion that 

 they are the same disease; that is, caused by the 

 same germ. 



In structure the nodules resemble an epithe- 

 lioma, described under that heading in the section 

 on tumors, and in that contagious chickenpox can 

 be transmitted from an emulsion of the material 

 of a pox nodule, by inoculating the face and comb 

 of a healthy bird. 



It has been proven that a maceration of the 

 scrapings from the pox in physiological salt solu- 

 tion and injected subcutaneously, will render im- 

 munity against further inoculation of the disease 

 by sacrification and introduction of the virus in 

 the face and comb. 



One investigator has claimed that chickenpox 

 is due to a protozoon (an animal parasite micro- 

 scopic in size), but other investigators have failed 

 to find this organism. 



Symptoms.— The disease appears as small nod- 

 ules, varying pin-point size up to the size of a pea, 



