OUR KNOWLEDGE OF INSECT VECTORS OF DISEASE. 



157 



The virus of acute anterior poliomyelitis is still not isolated with certainty. Flexner 

 and his colleagues have been able to cultivate a filterable micro-organism which 

 produced the disease in experimental animals, and more recently Rosenow and his 

 fellow- workers have isolated a polymorphous streptococcus with which they were also 

 able to produce paralysis in certain animals. Nuzum and Horzog were able to do 

 likewise by a gram-positive micrococcus isolated from the brain and spinal chord of 

 persons dead from the disease. Poliomyelitis has been very generally suspected of 

 being transmitted by insects, particularly by Stomoxys calcitrans (the stable fly), 

 fleas, and Tabanidae (gad-flies). Nevertheless it appears more likely that it has an 

 aerial transmission, infection being acquired through the buccal and nasal mucous 

 membranes. 



Wolbach claims to have discovered the causative organism of Rocky Mountain 

 spotted fever in the bodies of infective ticks (Dermacentor venustus). 



Table I. 



The more Important Insect-borne Diseases of Unknown Origin. 



(N.B. — Names in these tables marked with an asterisk are certain vectors ; names 

 not so marked are probable vectors ; names followed by (?) are possible 



vectors.) 



Organism. Host. 



Disease. 



Vector. 





I 



• 



Man. 



Dengue, or breakbone 

 fever. 



Sandflies (Phlebotomus),* mosquitoes 

 ( Culex fatigans). * 





\ 



>» 



Three -day fever (sandfly 

 fever, Phlebotomus 

 fever). 



Sandflies (Phlebotomus),* mosquitoes 

 (G. fatigans).* 





8 



»j 



Yellow fever. 



Mosquitoes (Stegomyia fasciata).* 





? 



>? 



Trench fever. 



Lice (?). 



% 



Salivary toxin 



>» 



Tick paralysis 

 (American). 



Ticks (Dermacentor venustus).* 



% 



Salivary toxin 



• 



Tick paralysis 

 (Australian). 



Ticks (Ixodes ricinus).* 





•> 



>> 



Rocky Mountain 

 spotted fever. 



Ticks (Dermacentor venustus).* 





-» 



- 



Japanese river fever 

 (Shima mushi). 



Mites (Larval Trombidiidae, " aka 

 mushi "). 





V 



»5 



Acute anterior polio- 

 myelitis (infantile 

 paralysis). 



Many insects have been claimed as 

 vectors, notably Stomoxys calci- 

 trans (%). 





! 



5> 



Pellagra. 



Flies of the genus Simulium (?) have 

 been claimed. 



