332 DISEASES OF UNCERTAIN .ETIOLOGY 



Pro. Sambon supports his view c!T; tlie basis of its being protozoan 

 because : — - 

 (i) There is a mononucleosis present in the blood. 



(2) There are long intervals of quiescence followed by relapse. 



(3) There is a constant and characteristic topographical dis- 

 tribution. 



(4) The symptoms, course, duration, and morbid anatomy are 

 similar to those found in other parasitic diseases. 



(3) Sambon found a spirochcCte in a bulla on the hand of a 

 severe pellagra case. 

 Con. No parasite has yet been found. 



Fluids from pellagrins have not reproduced the disease 

 when injected into other animals. 



A biting fly is bhivicd because: — 



It is a disease of rural districts essentiallv. 



It is in some way related to moving water. 



It has a definite seasonal influence, spring and autumn, which 



coincides with the appearance of certain flies. 



It affects labourers in the field. 



It is not contagious (Goldberger). 



Young children and whole families often are readilv affected in 



an endemic centre. 



Sambon suggests one of the simulidcv because: — 

 Their larv^ live in running water. 



They have two seasons, spring and autumn, when they attack 

 man and beast in swarms. 



But 



They are not found in the Xile, where pellagra is common. 

 The Illinois Commission does not agree on this point. 



(4) The Mineral Acidosis Theory. 



The findings of Professor Alessandrini and Scala of the Pellagra 

 Commission of Rome may be summarized thus : — 



Pellagra is strictly localized and limited to areas where the water 

 drunk has almost exclusively been in contact with clav. 



Clay is silicate of alumina. 



The action of rain water upon tliis produces bv hvdrolvsis silicic 

 acid and hydrate of alumina which pass into the water in a colloidal 

 form . 



A colloidal silica-alumina is formed, some as a deposit and some 

 remaining in suspension. 



