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6652
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No. 100.
REPORT BY DR. SAMBON UPON PELLAGRA IN THE WEST INDIES. (Received in Colonial Office, 9th February, 1915.)
I HAVE the honour to submit below a short preliminary report on my trip to the West Indies, made for the purpose of establishing whether the disease lately reported from some of the Caribbean Islands is genuine pellagra, and of studying so far as time would allow, the conditions under which it prevails, with a view to the adoption of suitable preventive measures.
In my forthcoming extended report I am giving a full account of the numerous researches and experiments made, from time to time, to elucidate the nature of pellagra Nevertheless, for the better comprehension and appreciation of the statements made in the present communication, I consider it necessary to preface the relation of my West Indian observations with a brief summary of the more recent developments in the study of the disease.
Previous Researches.
My researches and investigations concerning the etiology of pellagra began in the year 1900, when, returning from the Roman Campagna at the conclusion of experiments on the mosquito transmission of malaria carried out on behalf of the Colonial Office, Dr. G. C. Low and I had the opportunity of visiting the Lom- bardic pellagra district of Inzago and its well-known Pellagrosario.
Five years later, at the Leicester meeting of the British Medical Association, having made a careful study of the literature of pellagra, I ventured to announce the conclusions at which I had arrived. I suggested:-
L-That, having been reported from such widely sundered places as Europe, Egypt, Asia Minor, Mexico, and New Caledonia, pellagra, like malaria and leprosy, was obviously a disease of world-wide distribution, and, though probably still unrecorded, might be expected to be found in other intervening countries.
II. That, notwithstanding the universal acceptance of the Italian maize theory, the causation of the disease, when critically investigated, could not possibly be ascribed to the consumption of Indian corn (Zea mays), either sound or deteriorated.
III. That, if clinically and epidemiologically scrutinized, it would be found to exhibit all the features of an insect-borne infectious disease.
IV. That, judging by analogy, its causative agent might probably be some minute protozoal organism.
Since the publication of my Leicester paper, pellagra has been recognized in the United States of America, on the Isthmus of Panama, in British Guiana, in the Island of Porto Rico, in the Bahamas, in the Lesser Antilles, in Hawaii, in the Philippine Islands, in the Straits Settlements, in Nyasaland, in Natal, in Cape Colony. Finally, in the fall of 1912, I was able to show that pellagra prevails endemically throughout the British Islands, including the far north Shetlands.
The most important development, in so far as the investigation of pellagra is concerned, was the discovery of the presence of the disease in the United States of America, because, so soon as it was recognized to be a widespread, prevalent, and serious malady in the more Southern States of the Union, the American people set themselves to work out its elucidation with that earnestness, thoroughness, and ability which distinguishes them.
In October, 1908, a National Pellagra Conference was held in the city of Columbia, under the auspices of the State Board of Health of South Carolina. At this meeting my new etiological theory of the disease was strongly advocated by Dr. Noel M. Moore, of Augusta, Georgia, Dr. Edward J. Wood, of Wilmington, North Carolina, and Dr. J. H. Taylor, of Columbia, South Carolina.
The great prominence so suddenly given to the subject in the American medical journals, and the favourable acceptance of my views abroad by such men as Pro- fessor R. Blanchard in France, and Professor F. Rho in Italy, enabled me to arouse Dr. in this country some interest in the study of a disease which was known to be causing insanity and death in some of the British Colonies and Protectorates. James Cantlie, supported by Sir Patrick Manson, Sir Lauder Brunton, Sir William Osler, Sir Clifford Allbutt, Sir William Leishman, Professor W. J. Simpson, Dr. F. M. Sandwith, Dr. J. M. H. MacLeod, and other leading medical men, organized
71
a British Pellagra Commission and, with money collected by the committee, to which the Colonial Office contributed a grant, was able to proceed to Italy in the spring of 1910 to carry out a preliminary investigation.
The investigation lasted about three months (15th March to 12th June), and extended over the provinces of Milan, Bergamo, Brescia, Padua, Venice, and Perugia.
During the first six weeks I had the valuable co-operation of Dr. J. F. Siler, Captain Medical Corps, United States Army, who had already been engaged in the study of pellagra in Illinois, U.S.A. During the last six weeks I had the advantage of being joined in my researches by Dr. C. H. Lavinder, Passed- Assistant Surgeon, United States Public Health Service, who had been detailed to investigate the disease in Europe, and by Dr. Rupert Blue, now Surgeon-General, United States Public Health Service.
I
My researches in Italy in 1910 enabled me to establish quite definitely that pellagra is not in any way due to the eating of maize, either good or spoilt. found that the disease everywhere presented the same peculiar distribution, its stations or endemic foci being irregularly scattered, and always confined to well- defined rural areas intersected by swiftly running streams.
I was able to show that in certain provinces (Brescia, Padua, Belluno), for which we had the necessary records, both the areas of endemicity and of immunity had kept their respective locations practically unchanged for at least a century.
I noticed that, within its endemic areas, the disease had affected at one time or another practically the entire population, being, like malaria, especially mani- fest among the very young children, a fact of considerable epidemiological impor- tance entirely overlooked by previous observers.
Everywhere I found ample confirmation of the well-known fact that, in the absence of some as yet undetermined factor, pellagrin immigrants do not communi- cate their long continued disease to the inhabitants of non-pellagrous localities. notwithstanding the most intimate association, and that pellagrin wet-nurses who go to the large towns for fosterage never transmit the disease to the town-born children they suckle.
At Morra, near Citta di Castello, in the province of Perugia, I obtained evidence showing that, given the necessary ecological conditions, a previously immune locality may become an endemic centre of the disease in consequence of the immigration of pellagrins.
In various places I came across examples showing that robust, healthy people migrating to a pellagrous area usually contract the disease within their first year of residence.
By studying the disease in infants I was able to ascertain that the period of incubation may be shorter than a fortnight.
By a process of exclusion, after carefully considering all the available infor- mation concerning the epidemiology of the disease and the bionomics of the phleboto- mist Arthropoda. I was led to incriminate the Simuliidæ as the possible carriers of the pellagrous infection.
Fleas, lice, and bed-bugs were excluded because of the peculiar variations in the age and sex distribution of the disease in different places, and because of the well-known immunity of town folk, notwithstanding constant and intimate inter- course with pellagrins from the country. Mosquitoes were excluded on account of their domestic habits, and because pellagra and malaria, though overlapping in places, show a decidedly inverse distribution. The stable-fly (Stomoxys calcitrans) was discarded on account of its ubiquitousness. Pellagra is essentially. a rural disease, and its vector (if there be one) had to be looked for amongst the rural blood-sucking Diptera, such as the Chironomide and the Simuliidæ, because their habits, so far as they were known, seemed to explain most satisfactorily the striking peculiarities of the epidemiology of pellagra. In Italy I found them invariably present, and as a rule very prevalent, in all the pellagrous areas I had the opportunity of visiting.
In 1911, thanks to the keen scientific interest and ready generosity of Mr. Henry S. Wellcome, I was able to return to Italy for a short time, and to visit the best known pellagra districts of Spain, France, Austria, Hungary, and Roumania. In this second trip I had the invaluable assistance of Dr. Albert J. Chalmers, of the Ceylon Medical Service. Our researches fully confirmed previous observations, but left a doubt whether other small blood-sucking flies of the family