6i6 Insects and Disease 



of malaria, yellow fever, and the various forms of filariasis; house-flics 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 re{)ort of the work of Major Ronald Ross, 

 cne 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 ves.sels 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 

 larva; 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, 51,60x3 deaths occurred in Rio 

 Janeiro from this disease, and at times as many as 2000 patients have been 



