CHAPTER XIV 



Diseases Transmitted by Bloodsucking Flies-"^ 

 W, Dwight Pierce 



As stated before it was necessary to discuss the transmission of 

 diseases by flies in three lectures, non-bloodsucking flies, mosquitoes and 

 other bloodsucking flies. This is therefore the second lecture on fly- 

 borne diseases, and embraces quite a diff'erent category of diseases. For 

 convenience of reference and study it will be likewise handled from the 

 standpoint of the organism transmitted. The most important volume on 

 the subject of this lecture is by Hindle. 



PLANT ORGANISMS CARRIED BY BLOODSUCKING FLIES 



Thallophyta: Fungi: Schizomycetes: Bacteriaceae 



Bacterium tidarense McCoy and Chapin, the causative organism of a 

 RODENT PLAGUE, is probably normally carried by fleas, but Wayson 

 records some interesting experiments with the stable fly, Stomoxys cal- 

 citrans Linnaeus. He found that a fly after biting an acutely diseased 

 guinea pig eight times, if applied to a healthy animal within an hour, will 

 cff'ectively transmit the disease to the healthy animal and cause its death 

 in five to nine days. Washings of the flies in normal salt solution, and 

 also washings of the flies slightly crushed, when injected subcutaneously 

 will produce similar results. The transmission by bites occurs only from 

 those animals having an advanced stage of the bacteremia, as indicated 

 by their death within 24 to 48 hours after the fly feeding. The flies have 

 not been proven infective as long as 24 hours. This same organism has 

 been isolated from cases of DEER FLY FEVER or PAHVANT VAL- 

 LEY PLAGUE in Utah by Francis (1919). The disease is local and one 

 case in 1919 was fatal. The fever, lasting from 3 to 6 weeks, is said to 

 be initiated by the bite of deer flies (Chrysops). 



Bacterium anthracis Davaine, the causative organism of ANTHRAX 

 or charbon, can be carried by bloodsucking flies. Nuttall (1899) cites 

 many early references to the role of bloodsucking flies in the transmis- 



^This lecture was presented Octobe'* 7, 1918, and distributed October 19. It has 

 been somewhat modified for the present edition. 



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