[CHAPTER XXI]
INSECTS AS CARRIERS OF DISEASE
Some insects that carry disease
Certain diseases are given to human beings by the bites of insects. We know that certain ticks and mosquitoes carry certain germs. It is also probable that disease germs are transferred from diseased to well persons by bedbugs and other insects that bite.
How yellow fever is transmitted
For a long time it was thought that yellow fever was carried through the air, but now it has been proved that yellow fever is not carried in this way. A well person can sleep with one who has yellow fever and not catch the disease. Yellow fever infection is carried from a yellow fever patient to a healthy person only by a certain mosquito. Keep this mosquito away from the yellow fever patients and there can be no spread of the disease.
Fig. 48. The mosquito that carries yellow fever.
It is not many years since yellow fever was one of the most dreaded diseases in warm countries. To-day there is not the same fear of it, for the source of the disease has been discovered and practical methods have been devised to get rid of the mosquito which carries it.
How malaria is transmitted