Yellow Fever

an infectious disease peculiar to low, warm countries. It is a bacterial disease. The germs which were once thought to float in the air, it is now known are conveyed from the blood of one person to that of another through the agency of the yellow fever mosquito which breeds in low lands partly under water. After the mosquito has drawn blood from a fever patient it requires about twelve days for the germs to develop in the mosquito's body so as to be transferred by a mosquito bite to another person. Scientists go so far as to say that the fever can be transmitted in no other way. People who live in such countries become more or less hardened or immune, that is to say, the germs of the fever are not so likely to thrive in their blood as in that of strangers. An investigation of yellow fever epidemics at New Orleans, where it is at times prevalent, shows that the mortality among fever patients varies from four out of 1,000 for native white people, that is to say, creoles, to 329 per 1,000 for strangers. The mortality of negroes is less than that of creoles. The entire list runs negroes, creoles, strangers from the West Indies, from the Southern States, from Spain and Italy, the Middle States, New York, New England, Western States, France, British America, Great Britain, Germany, Scandinavia, Austria and Switzerland, and the Netherlands.

As in the case of smallpox and other infectious diseases, attempts have been made to inoculate against yellow fever, but without success. As a means of preventing the spread of the disease, yellow fever patients are surrounded by mosquito bars to keep the mosquitoes away. Most infectious diseases, as typhoid or cholera, spread more rapidly in unsanitary conditions, but filthy surroundings seem to have no effect on yellow fever, except as they further the breeding of mosquitoes. The entire problem seems to be one of exterminating or controlling this insect.

The geographical range of yellow fever is chiefly American, extending along the seacoast from Boston to Rio Janeiro, including the cities of the West Indies and Central America. It also extends up the Mississippi Valley as far as Memphis or St. Louis. It is believed that climatic conditions in other parts of the world would be favorable, if the mosquito and the germs were once established. Great pains are taken, therefore, to quarantine all ships and travelers from regions in which yellow fever is raging. The original home of yellow fever is believed to be the west coast of Africa, whence it was imported by the slave trade. The West Indies are the American center of the pestilence, whence it has been carried to the seaports of Spain and Portugal. An epidemic of yellow fever visited Philadelphia in 1793. Between August and the middle of September one person out of ten of the entire population died of the disease. Another serious invasion of the fever in the United States occurred in 1878 when over 15,000 deaths occurred in the lower Mississippi Valley. Since the Spanish-American War in Cuba in 1898 the danger of infection from Cuba has been considerably lessened owing to the thorough cleaning of the chief cities of the island by the Americans and their improved sanitary condition since. A frost hard enough to do up the mosquito never fails to stay the spread of yellow fever.

See Mosquito