"Sleeping sickness" destroys millions in Africa and has always prevented dense populations because the natives did not know how to avoid it. Modern science has discovered the cause and method of transmission, and under white man's control, it is quite likely that the disease will disappear. Similarly typhus fever attacked European crowds, but it has mysteriously disappeared, though we do not know why. Somehow modern sanitation keeps it out or renders us immune.
Cholera occasionally sweeps around the world, wiping out populations too concentrated to escape infecting each other. In Russia, for instance, in 1892 to 1894, it is said that 800,000 died of this disease, and in 1902-1903 several hundred thousands - no one knows exactly how many. This disease is now harmless in the higher civilized communities who know how to get good water and dispose of their excreta.
In the Philippines, though the native keeps his person scrupulously clean, the state of sanitation is low, as he is utterly unable to understand what we mean by our protective measures. Diseases are endemic and the population far beyond its saturation point. Smallpox was formerly endemic, but as every one had had it, the adults were nearly all immune, and it was confined mostly to the infants. It was like measles - a disease of infancy - and the adult native did not mind it. To be sure it killed about one-third or one-half of the little ones, but this was of no moment when each young woman has a new baby every year or two. If smallpox did not kill them something else would - all could not possibly survive. As a measure of self protection we vaccinated all the natives. By these means and other sanitary measures we were congratulating ourselves that we had saved 500,000 lives in the four years of our occupation. But what good was it? Cholera entered and in a few months destroyed 250,000 or more. Plague does not seem able to flourish in the Philippines, perhaps because the people live in houses on stilts, protected by this isolation from rat fleas. In Asia the people huddle in huts on the ground where they can harbor the pests and be infected.
In Porto Rico we stopped the ravages of smallpox and gained great renown for it. Have the natives profited, and do they thank us? The following news dispatch can answer: "United States officials in Porto Rico do not make concealment of their belief that the present wholesale emigration from the Island is a good thing for Porto Rico. They say that any method of relieving the crowded conditions of the Island, which are largely responsible for the misery and suffering everywhere manifest, will be a good thing for those who are left." But they need not worry over Porto Ricans, who can import food in plenty if they will only work their plantations and make something they can sell.