CHAPTER XI 
INFECTIOUS ENTERO-HEPATITIS OF TURKEYS 
Synonym. Blackhead. 
Characterization. Entero-hepatitis is an infectious disease of 
turkeys and fowls, characterized by distention of the ceca with ne- 
crotic material and the formation of yellowish or yellowish-green ne- 
crotic areas in the liver. 
Geographic distribution. It is widely distributed over the 
United States, and has also been reported from Canada, Europe, Aus- 
tralia and Africa. 
Etiology. The causative organism as described by Smith belongs 
to the genus ameba and has been designated by him Ameba mele- 
agridis. Through the researches of Hadley, the réle of an ameba in 
the causation is disputed. The latter investigator asserts that a fla- 
gellated protozoal organism, Trichomonas, is the causative agent and 
that the organism described by Smith merely represents a transitory 
stage in the life cycle of the flagellate. The difficulties to be met 
with in establishing the etiologic factor of this disease are far greater 
than is the case in bacterial affections. In routine examination of 
entero-hepatitis cases by the present writers, it has been observed that 
flagellate forms are frequently present in the cecal exudate of tur- 
keys dead of entero-hepatitis while more often protozoal organisms 
of the ameba type are seen in comparatively large numbers. Fur- 
ther and more extensive investigation appears to be necessary in order 
to establish firmly the specific etiology of this disease. 
The organism described by Smith is round or oval in form with 
a single contoured outline. The structure appears homogeneous 
throughout with the exception of a small granular area eccentrically 
located and representing the nucleus. This encloses a smaller 
rounded body distinguished as the nucleolus. The protozoa in fixed 
or hardened tissue are from 6 to 10 microns in diameter, in fresh. 
smears from 8 to 15 microns in diameter. 
The organism attributed by Hadley as the causative agent is a 
flagellate. ‘This is most easily recognized in the motile stage. In 
this form it presents an irregular outline. It may be pear shaped, 
ovoid, triangular or elliptical in form. It has three anterior fla- 
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