246 



Arthropod Transmission of Disease 



Pellagra 

 Pellagra is an endemic and epidemic disease characterized by a 

 peculiar eruption or erythema of the skin (figs 144 and 145), digestive 



disturbances and nervous trouble. 

 Insanity is a common result, rather 

 than a precursor of the disease. 

 The manifestations of pellagra are 

 periodic and its duration indeter- 

 minate. 



The disease is one the very name 

 of which was almost imknown in the 

 United States until within the past 

 decade. It has usually been regarded 

 as tropical, though it occurs commonly 

 in Italy and in various parts of Europe. 

 Now it is known that it not only 

 occurs quite generally in the United 

 States but that it is spreading. Lav- 

 inder (19 11) says that "There are 

 certainly many thousand cases of the 

 disease in this country, and the pres- 

 ent situation must be looked upon 

 ■\¥ith grave concern." 

 It is not within the scope of this book to undertake a general 

 discussion of pellagra. The subject is of such importance to every 

 medical man that we cannot do better than refer to Lavinder's 

 valuable precis. We can only touch briefly upon the entomological 

 phases of the problems presented. 



The most commonly accepted theories regarding the etiology 

 of the disease have attributed it to the use of Indian com as an article 

 of diet. This supposed relationship was explained either on the 

 basis of, (a) insufficiency of nutriment and inappropriateness of 

 com as a prime article of food ; (b) toxicity of com or, (c) parasitism, 

 of j^ certain organisms — fungi or bacteria — ingested with either sound 

 or deteriorated com. 



In 1905, Sambon proposed the theory of the protozoal origin^of 

 pellagra and in 19 10 he marshalled an imposing array of objections 

 to the theory that there existed any relationship between com and 

 the disease. He presented clear evidence that pellagra existed in 

 Europe before the introduction of Indian com from America, as an 



144. Pellagrous eruption on the face. 

 After Watson. 



