CHAPTER XVII 



Diseases Transmitted by Mosquitoes ^ 

 W. Dwight Pierce 



Probably more entomologists and sanitarians are familiar with the 

 facts of mosquito transmission of disease than with any other phase of 

 our subject, but a review of their role will not be amiss, especially as it 

 will be presented in a different form from that usually adopted in text 

 books. In this volume all of the chapters on disease transmission are 

 handled in one manner, that is, by a systematic arrangement of the 

 organisms transmitted. We may perhaps get a new conception of the 

 relation of mosquitoes to parasitic organisms by this arrangement. Those 

 organisms which are parasitic only need to be listed in order that 

 students take into account the possibility of confusing them with the 

 pathogenic organisms being sought. 



Teachers using these lectures as material for the study of their 

 classes may find it of value to have the students make rearrangements 

 of the subject by the name of the disease or the species of insects involved, 

 or by the method of transmission. 



In our study of the non-bloodsucking flies we found that the disease 

 transmission was principally through the feces, although also through 

 the vomit, but never by direct inoculation. In the discussion of the 

 bloodsucking flies it was shown that they usually transmitted disease 

 while in the act of sucking blood. All known cases of disease transmission 

 by mosquitoes are by direct inoculation at the time of the bite. In dengue 

 fever the organism has not been demonstrated ; in malaria of all types we 

 have a known organism which undergoes a definite life cycle in the mos- 

 quito ; in filariasis we also have the mosquito serving as an intermediate 

 host for the early stages of the worm. 



For complete studies of the life history of the malaria organism in 

 the mosquito refer to Hindle (1914) in which you will also find lists of 

 Anopheles of the world, with tables for identification, tables of malaria 

 carriers and much more of a valuable nature, which should be carefully 

 studied. Many other works deal very carefully with the subject, how- 

 ever. The names of mosquitoes used in this and following lectures are on 

 the authority of the late Frederick Knab. 



*This lecture was presented August 19 and issued August 23, 1918, and has been 

 more or less modified to its present form. 



247 



