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Page:Popular Science Monthly Volume 65.djvu/268

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of the epidemiology of typhoid fever. The most original and valuable work of the board is the proof that the infection of typhoid fever is spread in camps by the common fly, and by contact with patients and infected articles, clothing, tentage and utensils, as well as by contaminated drinking water.

In June, 1900, Major Reed was sent to Cuba as president of a board to study the infectious diseases of the country, but more especially yellow fever. Associated with him were Acting Assistant Surgeons James Carroll, Jesse W. Lazear and A. Agramonte. At this time the American authorities in Cuba had for a year and a half endeavored to diminish the disease and mortality of the Cuban towns, by general sanitary work, but while the health of the population showed distinct improvement and the mortality had greatly diminished, yellow fever apparently had been entirely unaffected by these measures. In fact, owing to the large number of non-immune foreigners, the disease was more frequent than usual in Havana and in Quemados near the camp of American troops, and many valuable lives of American officers and soldiers had been lost.

Reed was convinced from the first that general sanitary measures alone would not check the disease, but that its transmission was probably due to an insect. The fact that malarial fever, caused by an animal parasite in the blood, is transmitted from man to man through the agency of certain mosquitoes had been recently accepted by the scientific world; also several years before, Dr. Carlos Finlay, of Havana, had advanced the theory that a mosquito conveyed the unknown cause of yellow fever, but did not succeed in demonstrating the truth of his theory.

Dr. H. R. Carter, of the Marine Hospital Service, had written a paper showing that although the period of incubation of yellow fever was only five days, yet a house to which a patient was carried did not become infected for from fifteen to twenty days. To Reed's mind this indicated that the unknown infective agent has to undergo a period of incubation of from ten to fifteen days, and probably in the body of a biting insect. Up to this time the most generally accepted theory as to the causation of yellow fever was that of Sanarelli, who claimed that the Bacillus icteroides discovered by him was the specific agent of the disease. Major Reed, in association with Dr. Carroll, had, however, already demonstrated that this bacillus was one widely disseminated in the United States, and bore no special relation to yellow fever.

In June, July and August, 1900, the commission gave their entire attention to the bacteriological study of the blood of yellow fever patients, and the post-mortem examination of the organs of those dying with the disease. In twenty-four cases where the blood was repeatedly examined, as well as in eleven carefully studied autopsies, Bacillus icteroides was not discovered, nor was there any indication of the presence in the blood of a specific cause of the disease.