THE RELATION OF MOSQUITOES TO MAN. 
THE CARRIAGE OF DISEASE BY MOSQUITOES. 
That certain mosquitoes are an essential factor in the propagation of certain 
diseases is now well demonstrated and generally accepted. In every case where 
such relation of the mosquito has been proved the réle of the insect is not that of 
a purely mechanical carrier or transmitter, as is, for example, the conveyance of 
typhoid fever by the house fly. The diseases in question are caused by organisms 
which have a complex life-cycle, part of which is passed in man and part in the 
mosquito, and in the absence of one or the other of the hosts their existence or 
continuance is impossible. In other words, the causative organisms of these 
diseases, as far as we know them, are animal parasites. These parasites can 
exist only in definite hosts. This restriction goes so far that a given parasite is 
restricted, on the one hand to a certain vertebrate host (for example, man, the 
dog, the sparrow), on the other to a certain species of mosquito. It is the full 
recognition of these facts that has made the thorough investigation of mosqui- 
toes, systematically and biologically, such an important study. 
In the following, the causative organisms, their life-cycles, and the mosquitoes 
concerned in each case, are discussed under the heading of the respective diseases. 
EARLY IDEAS. 
The idea that mosquitoes carry disease is not only very old historically, but 
occurs among primitive nations in various parts of the world. References have 
been found in the very early literature of India, in writings that are practically 
prehistoric, that indicate that the idea was held in those early days, especially 
with reference to malaria. The natives of different parts of Africa and in Assam 
are said to hold the same idea, and it has been pointed out that the belief has 
long been prevalent among the Italian peasants and among those in the southern 
Tyrol. According to Humboldt the inhabitants of the upper Orinoco at the time 
of his visit accused the mosquitoes of being the cause of the febrile maladies from 
which they suffered. Koch points out that the negroes of the Mschamba tribe 
on Mount Usambara in Africa do not descend into the lower regions on account 
of fear of fever. Fever in their language is called mbui and mbz is also their 
name for mosquito, indicating that they understand the connection between the 
two so perfectly that they have but one name for both. 
Dr. A. F, A. King, of Washington, in an important paper published in 1883, 
called attention to an article by John Crawford entitled: “ Mosquital Origin 
of Malarial Diseases,” said to have been published in the Baltimore Observer in 
1807, but subsequent investigations by Dr. King and Dr. W. S. Thayer, of 
Baltimore, have failed to find the article, either in the newspaper itself, or in a 
review of Crawford’s papers published in the Baltimore Medical and Physio- 
logical Recorder, 1809. 
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