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 unknown 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 
vStates but that it is spreading. Lav- 
inder (1911) says that “There are 
certainly many thousand cases of the 
disease in this country, and the pres¬ 
ent situation must be looked upon 
with 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 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 1910 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 corn from America, as an 
