January 17, 1913] 



SCIENCE 



89 



and in August of three of them; while in the 

 two years for which our records are virtually 

 complete, the first wave is the highest in 1910, 

 and the second is highest in 1911. 



I believed at one time that we might make 

 out a relation of succession between these 

 separate waves of increase and the adult 

 periods of successive generations of Simuliuin, 

 but as my data accumulate this relationship 

 becomes decidedly doubtful; and certainly 

 these double pellagra periods can not be con- 

 nected with any seasonal differences in the 

 abundance of Simulium. If there were any 

 causal relation between these two facts there 

 should be but one high pellagra period to cor- 

 respond with the single spring outrush of 

 Simulium adults; or if there were another it 

 should be much lower than the first. 



Sambon reports a periodical character dif- 

 ferent from this observed in Illinois in the 

 fact that it relates to an increased activity of 

 pellagra — an intensification of its symptoms 

 in individual pellagrins — occurring in spring 

 and in fall, coincident, as he says, in Italy 

 with the time of flight of two generations of 

 the sand-flies ; and he uses this fact to support 

 his hypothesis of the dependence of the dis- 

 ease on the. insects. Assuming that pellagra 

 is produced by a protozoan parasite, he fur- 

 ther assumes that the aggravation of symp- 

 toms twice each year is due to a migration to 

 the surface of this hypothetical parasite, 

 which is thus exposed to be taken up by the 

 sand-flies as they draw blood from the skin 

 of pellagrins. The summer and fall recrudes- 

 cences of the disease he thus connects with 

 the summer and fall abundance of the sand- 

 fly imagos. His periods are, however, dif- 

 ferent from ours, the first coming in March 

 or April instead of May and June, and the 

 second in September or October, instead of 

 August as in Illinois. I have not been able to , 

 learn from our physicians that any periodicity 

 similar to this described by Sambon has been 

 noticed in Illinois cases, but if it has it would 

 be impossible to correlate it with the facts 

 above described concerning the development 

 of Simulium in our state. 



There are other interesting points of con- 



trast between our Illinois conditions and con- 

 clusions and those obtained by a study of the 

 problem in Italy and in other parts of Europe. 

 We are told, for example, that in Italy pel- 

 lagra is a rural disease, to which town-dwellers 

 are virtually immune, even where there is 

 free communication between the town and 

 adjacent pellagrous districts; but in Illinoia 

 we have every year several deaths from pel- 

 lagra in our largest city, with a population of 

 more than two million souls. Four cases of 

 this disease have lately been reported to me 

 from the private practise of Dr. Oliver S. 

 Ormsby, secretary of the State Pellagra Com- 

 mission, the sufferers from which had lived 

 continuously in Chicago for years. Pellagra, 

 in fact, can scarcely be said to be with us, as 

 yet, a rural disease, the asylums in which 

 ninety-six per cent, of the known new cases 

 have occurred being in or very near cities and 

 towns, and all cases reported from outside 

 such institutions having come from the town 

 and not from the country. The Peoria 

 asylum, containing sixty-three per cent, of our 

 known pellagrins, is in a suburb of our sec- 

 ond largest city. It draws its patients from 

 all parts of the state, but more than a third 

 of them come from Chicago or its immediate 

 neighborhood. Three other asylums, contain- 

 ing thirty per cent, more of our pellagrins, 

 receive between sixty-three and one hundred 

 per cent, of their inmates from Chicago. The 

 closest relations of these especially pellagrous 

 asylums thus seem to be with our largest 

 cities and not with our rural districts. These 

 facts would be more certainly significant, 

 however, if pellagra had been longer known 

 and more thoroughly studied throughout our 

 territory, and if we had complete and reliable 

 statistics from the state at large. 



Simulium is said in Italy not to live in 

 towns or to enter houses; but in the town of 

 Havana, a village of thirty-six hundred in- 

 habitants situated on the Illinois Eiver near 

 the central part of my state, it is so great a 

 pest in spring that the people screen their 

 windows to protect themselves from the bites 

 of the black-flies; and we have seen these 

 insects collecting there in great numbers on 



