DISTRIBUTION OF DISEASE GERMS 101 



mosquito, Culex, does not, so far as we know, carry any disease 

 germ. Yellow fever is produced by another animal germ that 

 is carried by the mosquito known as Stegomyia (fig. 55). 



115. Disease germs distributed by other insects. House flies 

 and mosquitoes are not the only insects that transmit diseases. 

 It is known that the germs of bubonic plague are transmitted 

 from person to person by a kind of flea that commonly lives 

 upon rats. The rats are subject to the plague., and when they 

 die from it the infected fleas leave their bodies and find new 

 hosts. If they take up their abode on the body of a human 

 being, their bites will probably infect the person with the 

 plague bacteria. Very obviously the disease is much less 

 likely to attack the careful and cleanly person, living in a 

 well-kept dwelling, than it is to attack his less cleanly, vermin- 

 infested neighbor. The only complete protection from the 

 disease in countries in which it is prevalent is to be .secured 

 by the total destruction of the rat population. The facts men- 

 tioned above explain how it is that in such a country as India 

 the natives may die of the plague in great numbers, while 

 their European neighbors, with cleaner surroundings, usually 

 escape. During the Middle Ages, when all dwellings, from 

 the hovel of the peasant to the palace of the king, were un- 

 sanitary and infested with vermin, epidemics of the plague 

 and other diseases frequently swept Europe, but in modern 

 times nothing of the sort is likely to occur in enlightened 

 nations. 



Various other insects, as bedbugs, roaches, and certain flies, 

 have been accused of carrying different diseases. The very 

 deadly spotted fever is carried by a tick, and another tick 

 carries the Texas fever of cattle. 



