Dr. Manson has pointed out an interesting possible result of the crusade that is now being waged against the yellow fever mosquitoes. The immunity of the people native to the endemic regions is supposed to be due to their having had mild attacks of the fever during childhood, for the children in these regions are subject to certain fevers which are probably very mild forms of yellow fever.
Now if we kill practically all of the Stegomyia so that these children do not have this fever there will be developed, in due time, a population most of whom are non-immune.
This freedom from the disease for some time will allow us to grow careless in regard to fighting the mosquitoes. They will be allowed to increase and by some chance the yellow fever will again be introduced and there will then be very grave danger of most extensive and destructive epidemics.
DANGER OF THE DISEASE IN THE PACIFIC ISLANDS
I have already referred once or twice to the conditions in many of the Pacific tropical islands. In some of these various species of Stegomyia are abundant, and in some Stegomyia calopus is the most abundant and troublesome form. All the natives of these islands are non-immune because there has never been any yellow fever there. Unless extraordinary care is taken the disease will be introduced there sooner or later and the results are sure to be most appalling. The climatic and sanitary conditions and the habits of the people are ideal for the development and spread of the disease, and what I have seen of the conditions on some of these islands convinces me that it would be almost impossible to control the disease before it had a chance to kill a large percentage of the population.
With the opening of the Panama Canal these things become more possible. Heretofore, the shipping to these regions has not been from ports where yellow fever was endemic or even likely to be epidemic. But unless the yellow fever is kept out of the canal zone, the danger will be many fold what it is now.
The white man has already carried enough misery to these island peoples in the way of loathsome diseases, and it is to be hoped that this, another great curse, will not be carried to them with our civilization, the beneficial results of which have been so often very justly questioned.
What I have said in regard to these islands applies with equal force and in some instances with even greater force to parts of Asia, the Eastern Archipelago and other places.