PELLAGRA 



Pathology. — As the causation of pellagra is entirely unknown, 

 the pathology must be purely speculative. 



The Zeists see in the phenomena exhibited by the morbid anatomy 

 and histopathology changes which appear to them allied to those 

 found in scurvy, beri-beri, or ergotism, and believe that these 

 changes support the maize theory. 



The Fagopyrists see in the phenomena found in the skin lesions 

 as well as in those of the rest of the body the signs and symptoms 

 which can be produced in white animals fed on maize and exposed 

 to sunlight, and believe that these changes support the photo- 

 dynamic theory. 



Those who support the Parasitic Theory quote the mononucleosis 

 of the blood, the leptomeningitis, the perivascular infiltration, 

 and the primary degeneration of the nerve cells, as well as the 

 long intervals of apparent quiescence, as phenomena similar to 

 those seen in syphihs and sleeping sickness, and therefore beheve 

 that these changes support the parasitic theory. 



Sambon, however, has extended the parasitic theory by arguing 

 that the erythemata appearing on the hands, feet, face, and neck, 

 and more rarely on the genital organs, in the spring and autumn, 

 are brought about by the combined action of the parasite, whatever 

 it may be, and sunhght in correlation with the habits of some 

 biting fly. From epidemiological studies he suggested that some 

 member or members of the family Simuliidfe might be the insect 

 in question. He came to this conclusion because of the knowm 

 habits, life-history, etc., of the Simuliidse, which were in general 

 agreement with the epidemiology of pellagra. 



The reason why there is such a confusion of ideas with regard 

 to the pathology is not difficult to understand, as a post-mortem 

 made on a case of acute pellagra within an hour or so of death 

 is of great rarity, and has often been performed under conditions 

 of difficulty as regards cleanliness or preparation. Post-mortems 

 on cases of recurrences or of chronic pellagra have been abun- 

 dantly performed under the best auspices, but the main features 

 of the disease are often obscured by secondary changes ; while 

 even in the acute cases the phenomena are complicated by the 

 presence of malaria, typhoid, tuberculosis, syphilis, etc. 



Notwithstanding all these objections, there is some evidence in 

 favour of an early lesion of the central nervous system, especially 

 the posterior portion of the spinal cord in the lower cervical and 

 dorsal regions, as congestion and haemorrhages have been found 

 there, while in the more chronic condition degeneration of the 

 cells in the posterior cornu, in Clarke's column, and in the spinal 

 ganglia have been seen, as well as the later degeneration of some 

 of their axones. Further, according to Brugia, acute degenerative 

 changes can be seen in the cells of the sympathetic ganglia of the 

 cervical and abdominal regions associated with a diffuse, round- 

 celled infiltration of the interstitial tissue, which eventually leads 

 to sclerosis. Degenerative changes have also been recorded in 



