Pellagra 251 



"In May, 1913, in company with Capt. J. F. Siler of the Thomp- 

 son-McFadden Pellagra Commission, I visited the region of which 

 Midland in Midland County is the center. This region is very dry 

 and totally devoid of running water for a long distance in every 

 direction. The only natural source of water-supply, a few water 

 holes and ponds, were visited and found to be of such a nature that 

 the survival of Simulium, far less its propagation in them, is abso- 

 lutely impossible. The nearest stream affording possibilities as a 

 source of Simulium is 60 miles away, while the average distance of 

 such possibility is not less than 100 miles." 



11 Artificial sources of water-supply were also investigated care- 

 fully and were found to offer no opportunity for the breeding of 

 Simulium. 1 ' 



"At Midland the histories of five cases of pellagra were obtained, 

 which gave clear evidence that this place or its immediate vicinity 

 was the point of origin. Persons of long residence in the country 

 were questioned as to the occurrence of such flies as Simulium and 

 returned negative answers. These included a retired cattle owner, 

 who is a man of education and a keen observer, an expert veterinarian 

 stationed in the country who has the cattle of the country under 

 constant observation, and a practical cattle man, manager of a ranch 

 and of wide experience. The latter had had experience with 'Buf- 

 falo gnats' in other localities (in the East) and is well acquainted 

 with them. His close personal supervision of the cattle under his 

 charge, makes it practically certain that he would have discovered 

 these gnats had they been present in the country." 



"At the time the study was made, Simulium was breeding and 

 active in the adult state in the vicinity of Dallas, Texas, in the 

 eastern part of the state. We have here a region in which cases of 

 pellagra have originated, yet in which Simulium does not and cannot 

 breed." 



Other possible insect vectors of pellagra have been studied in 

 great detail and the available evidence indicates that if any insect 

 plays a rdle in the spread of the disease, Stomoxys calcitrans most 

 nearly fills the conditions. This conclusion was announced by 

 Jennings and King in 1912, and has been supported by their subse- 

 quent work. 



Yet, after all the studies of the past decade, the old belief that 

 pellagra is essentially of dietary origin is gaining ground. Gold- 

 berger, Waring and Willets (1914) of the United States Public Health 



