YELLOW FEVER, an infectious con tinued fever, ushered in with languor, chilliness, and more or less severe lum bar pains and frontal headache, coun tenance flushed, eyes at first humid, then suffused, and ultimately ferretty, skin imparting a tingling heat to the touch, and, as the second stage advances, grad ually acquiring a lemon or greenish yellow tinge, mind usually disturbed with hallucinations, or more or less vio lent delirium, restless watchfulness, or, possibly, drowsiness even to extreme coma, epigastric uneasiness, spontaneous vomiting without effort, first of a clear glairy fluid, but subsequently with coffee-ground flocculi, or blood itself, often, toward the close, with irrepres sible hiccough, and wild shrieking or melancholy wailing, tendency fatal, but the disease generally confers an im munity from subsequent attacks.
The first recorded outbreak of yellow fever occurred in the West Indies in 1647, and since that time it has been re curring at regular intervals in an epi demic form, and gradually extending its range; but it is endemic in certain lo calities, and notably so in the islands of St. Thomas and Santo Domingo. Regard ing its altitudinal and horizontal ranges Dr. Macdonald says: "It may be very well to assign an altitudinal limit of the spread of yellow fever, and, roughly speaking, this may be estimated at be tween 2,000 and 3,000 feet above the level of the sea, but the local conditions of every country seem to determine a range peculiar to itself. Thus the dis ease has been known at Newcastle, Ja maica, at an elevation of 4,000 feet, while in the valley of the Mississippi its highest recorded range is about 600 feet (admitting the fever of Gallipolis to be of the genuine type). Humboldt al ludes to the farm of Encero, in Mexico, at an elevation of 3,243 feet, as the alti tudinal limit of the black vomit. At Santo Domingo the encampments of the French in 1792 and of the English in 1796 en joyed an immunity from the disease, while it was spread far and wide among the troops in the low country. Though the West Indian Islands, and the neigh boring coasts of North and South Ameri ca, may be looked on as the focal area of yellow fever, yet, taking the outlying points at which its occurrence in the epidemic form has been recorded, its geographical range must be regarded as very considerable indeed, i. e., between Ion. 97° W. and 2° E., and between lat. 48° N. and 35° S. At least for the space of a century and a half, up to the year 1850, the Amazon river, dividing the Brazils from Guiana, limited the ex tension of yellow fever S. of the line; and while the disease was raging at Rio and Bahia, at the close of that epoch, the Montevideans flattered themselves that they were without the geographical limits of the pestilence, till it fell to their turn to sustain its visitation several years later, when the illusion was dispelled.
Similar facts may be adduced regarding the extension of the disease along the shores of the Pacific; so that, however well we may be acquainted with its pres ent range, making all due allowance for temperature, we cannot tell what the future may bring forth. In this connec tion it may be mentioned that a temper ature of at least 72° is assumed to be es sential to the development of yellow fever, though cases exceptional to this rule may now and then happen. Yellow fever is communicated from one person to another only by a species of house mosquito (Stegomyia fasciata). As a result of this knowledge it was entirely eliminated from the Panama Canal zone, and from other tropical areas, including Havana.
In December, 1878, a board of experts, consisting of twelve medical men and a sanitary engineer, with Surgeon-General Woodworth as president, was appointed by the Health Committees of the Senate and House of Representatives of the Congress of the United States to investi gate the yellow fever epidemic, and they came to the following conclusions: (1) Yellow fever is a specific disease, due to a specific poison which has not been chemically or microscopically demon strated, nor in any way made evident to the human senses; it is material and particulate, and endowed with the vital properties of growth and reproduction; the disease is not malarial, and malarial influences do not contribute toward its dissemination or mortality to any greater extent than to other epidemic diseases; a concurrence of local conditions seems to be necessary to the evolution of the disease, but what these are we have no positive knowledge. (2) Yellow fever is a disease of singular local attachments, often prevailing in a very small section of a city, with remarkable indifference to topographical and social surround ings; while atmospheric air is the usual medium by which it is conveyed, it has been in no instance established that the disease has been carried to any consider able distance by atmospheric currents, or by any modes or vehicles of conveyance other than those connected with human traffic and travel; the period of incuba tion varies from two to five days; the fever is unknown in Asia; the white race is most susceptible to its in fluence, and furnishes the highest ratio of deaths.