6 



INSECTS AND HUMAN WELFARE 



(4) Mosquito-borne disease may be combated either by the 

 ehmination of the mosquito responsible; by the protection 

 of the popuhxtion from its bites; by the careful screening of 

 human patients to prevent tliem from infecting mosquitoes; 

 or by a medical prophylaxis or inmiunization of the suscept- 

 ible population. (5) Remedial measures are preferably ap- 

 plied against only the specific mosquitoes responsible, not 

 against mosquitoes in general. The last is primarily a matter 

 of economy, that the most vital needs of the community be 



Fig. 1. Distribution of Malaria in the United States. (After Trask.) 



first fulfilled; often more willingness on the part of the com- 

 munity is evinced to cooperate in fighting the most annoying 

 or abundant species of mosquitoes rather than the ones most 

 deleterious to the public health. 



Of these methods, the first has proved the most generally 

 applicable, preferably combined with the second and third. 

 The last has not proved generally suitable even with malaria, 

 where quinine is a specific remedy, or with plague, where 

 immunization is possible. 



One of the best known insect-borne diseases, and one which 

 is of great importance in many parts of our own country is 

 malarial fever, variously termed ague, chills and fever, etc. 

 This was the first human disease traced directly to insect 

 carriers and gave the impetus which has led to the unraveling 

 of the facts connected with other insect-borne diseases. 



