Page:Popular Science Monthly Volume 13.djvu/737

This page has been validated.
717
YELLOW FEVER.

vomit, indicating, as it does, a profound disorganization of the blood, is, in most cases, a fatal sign. Alvarenga states that, in the epidemic of 1857, at Lisbon, out of one hundred and seventy-eight cases of black vomit, forty recovered, but this is an isolated experience, and in this country, at least, such recoveries are rare. The mortality varies between five and seventy-five per cent, of those attacked.

The disease develops in from one to fourteen days after exposure. Those most liable to it are strangers or recent comers. Old residents enjoy a certain immunity, excepting in severe epidemics, and, even if they are attacked, the disease is generally mild. Women and children, old persons, and those of delicate constitutions, are visually less liable to it than robust, healthy men. This year the children are said to have suffered most. The negro natives are generally exempt, though it has been noticed that negroes who have left the South for the North, and have returned during an epidemic, do not possess this immunity. In the present epidemic, even the negroes seem to succumb in great numbers. It is a singular fact that persons exposed to offensive effluvia when working at their trade, as tanners, butchers, soap-boilers, and scavengers, are almost exempt from the disease, while those whose trade exposes them to great variations of temperature, as bakers and cooks, are extremely prone to it. Like small-pox, it may occur more than once in the same person, but, as a rule, those who have had it once are never attacked again.

All methods of treatment agree in the principal points. The bowels must be cleared at the start, and the patient kept perfectly quiet. The temperature is kept down by applications of cold water, and ice is applied to the head if symptoms of congestion of the brain appear. The excessive thirst is relieved by swallowing lumps of ice, and the nausea controlled to some extent by iced lemonade or champagne. In the West Indies, lemon-juice plays an important part in the treatment, and the old negro nurses rub it over the surface of the body. When the appetite revives, great caution has to be exercised, as a premature return to solid food may result fatally.

The first fully recorded outbreak of the disease was in the West Indies in 1647, and since then it has recurred at irregular intervals, and has gradually extended its range. Epidemics have occurred as far north as Quebec and as far south as Montevideo, as far west as Mexico and as far east as Algiers. It is endemic in the West Indies, Venezuela, New Granada, and Mexico, on the easterly coast of the United States as far north as Charleston, South Carolina, and on the northerly coast of Africa. To become epidemic, it requires a mean temperature of at least 72°, and Griesinger holds that the temperature must be as high as 80° for a considerable time before it can acquire a foothold, though West Indian physicians have seen the temperature fall suddenly just before an outbreak. If the temperature falls during an epidemic its severity abates, and at 32° it disappears entirely. It