PELLAGRA 



[3. It has a definite seasonal incidence — spring and autumn— 

 which coincides with the appearance of certain flies. 



4. It largely affects field labourers and new residents in endemic 

 areas. 



5. It is not contagious, and neither food nor water can account 

 for its peculiar epidemiology. 



6. In the endemic centres it affects all ages, both sexes (as a 

 rule, females are more frequently attacked than males). 



7. An endemic centre is one in which it is usually easy to find 

 young children with the symptoms of the disease. 



8. In endemic centres whole families may show signs of the 

 disease, but outside these only one or two individuals may be 

 affected. 



Researches on the Island ofBurano in the Venetian Lagoon. — With 

 regard to the theory of a biting fly, Sambon is supported by the 

 inquiry into the pellagra of the Island of Burano made by himself, 

 Colonel Belli, and one of us, in which it was found that the fisher- 

 men and the boys who went fishing with them, were attacked by 

 the disease, while the men who worked in the Venice Arsenal were 

 said by the medical authorities to be free from the disease. The 

 women, the girls, and the young children showed no signs of pellagra, 

 with the exception of two or three women, who gave a history of 

 working on the mainland or on other islands adjoining. Many 

 of these young children, girls, and even women, were alleged 

 never to have moved from Burano, with the exception in some 

 instances of an occasional visit to Venice. These points are con- 

 trary to the maize theory, as all the inhabitants in Burano eat maize. 

 They are also against a hereditary transmission of the disease, for 

 with pellagrous fathers it would be imagined that the young children 

 should show signs of pellagra, especially as the male influence is 

 said to be preponderant by those who believe in the heredity of 

 pellagra. They are against sexual infection, as the women would 

 acquire the disease; they are against infection by contact, by 

 kissing, etc., because certain men and boys have the disease, but 

 the women and girls are remarkably free; they are against a para- 

 site being carried from the sick to the healthy by house parasites, 

 such as bugs or fleas, or personal parasites, such as lice. The 

 difference between the persons who suffered from pellagra in Burano 

 and those who did not appeared to be the fact that the former 

 either worked upon other islands or fished on the lagoon and up 

 the streams leading into the lagoon. On the other islands and on 

 terra-firma there are plenty of pellagrins, and everywhere there is 

 a history of small black biting flies occurring on quiet days in the 

 early morning or late evening. 



Sambon considers that the peculiar feature of the erythema 

 coming in the spring and the autumn must be a correlation with 

 some insect, and considers that the Simuliidse or some allied family 

 would be the most likely to supply the requisite fly. He chose first 

 the Simuliidse because its larvae lived in running water, and because 



