Insects and Disease 
616 
of malaria, yellow fever, and the various forms of filariasis; house-flies aid 
in spreading typhoid fever and other diseases; fleas are agents in distribut¬ 
ing the germs of bubonic plague. Other insects are known to spread other 
diseases. Howard says: “While in malaria and typhoid we have two 
principal diseases common to the United States which may be conveyed 
by insects, the agency of these little creatures in the transfer of the disease-germs 
is by no means confined to human beings. In Egypt and in the Fiji Islands 
there is a destructive eye-disease of human beings the germs of which are 
carried by the common house-fly. In our southern states an eye-disease 
known as pinkeye is carried by certain very minute flies of the genus Hip- 
pelates. The so-called Texas fever of cattle is unquestionably transferred 
by the common cattle-tick, and this was the earliest of the clearly demonstrated 
cases of the transfer of disease by insects. In Africa a similar disease of 
cattle is transferred by the bite of the famous biting fly known as the tsetse- 
fly. The germs of the disease of cattle known as anthrax are carried by 
gadflies, or horse-flies, and when these flies subsequently bite human beings 
malignant pustules may result. And other discoveries of this nature are 
constantly being made. Even the common bedbug is strongly suspected 
in this connection.” 
These statements are not guesses; they are proved facts of science. It 
will be some time before these facts and their significance receive their full 
recognition in medical practice; the knowledge of medicine is always in 
advance of its practical recognition. But modern medical practice is much 
swifter to incorporate the new facts of biology than was the practice of even 
a decade or two ago, and in such lines of work as army and other govern¬ 
mental service the new methods of preventive medicine are quickly adopted. 
Already there are organized movements all over the world to make use of 
the new knowledge concerning the relation of insects to human disease. 
As I write these pages comes the report of the work of Major Ronald Ross, 
one of the discoverers of the malaria-disseminating capacity of the mosquito 
and one of the leaders in the anti-mosquito crusade, in nearly stamping out 
malaria in the long notorious pest-hole of Ismailia. Malarial cases have been 
reduced there from 300,000 cases annually to 300, by effective war on mos¬ 
quitoes. Dr. Cruz reports that Rio Janeiro has abolished its old-fashioned 
quarantine regulations, and vessels with yellow fever on board will hereafter 
simply be disinfected and supervised. In October, 1903, Cruz directed the 
operations of twelve hundred men specially employed in destroying the 
larvae of the mosquito in their breeding-places in and around the city, and as 
a result only nine cases of yellow fever developed in the midsummer months 
of January and February (1904), as against 275 cases in the same months 
in 1903. In the period from 1850 to 1896, 51,606 deaths occurred in Rio 
Janeiro from this disease, and at times as many as 2000 patients have been 
