OUR KNOWLEDGE OF INSECT VECTORS OF DISEASE. 



159 



Table II cont. 



Organism. 



Host. 



Disease. 



Vector. 



Bartonia hacilliformis 



Man 



Verruga 



Phlebotomus verrucarum.* 



Spirillum cholerae 



Man 



Cholera 



Flies,* cockroaches, ants. 



Micrococcus melitsntds . . 



Man and 

 goats. 



Undulant fever 

 (Malta fever, 

 Mediterranean fever, 

 remittent fever). 



Flies,* although the main 

 channel of infection is 

 the consumption of goat's 

 milk.* 



Diplococcus intracellularis 



Man 



Cerebro-spinal fever 



Flies (?)• 



Diplococcus pemphigiconta - 

 giosi. 



Man 



Tropical impetigo 



Lice. * 



Notes to Table III. — Diseases of Spirochaetal Origin. 

 With these diseases the usual method of transmission is direct, that is to say, through 

 the bites of the insect vectors. A possible exception occurs in the case of yaws, 

 where Musca domestica may at times convey the organism from diseased to healthy 

 persons. 



Table III. 



The more Important Insect-borne Disease of Spirochaetal Origin. 



Organism. 



Host. 



Disease. 



Vector. 





Spirochacta carteri 



Man 



Indian relapsing 

 fever. 



Lice. * 





„ duttoni 



Man 



African relapsing 

 fever (tick fever). 



Ticks ( Ornithodo rv s 

 bata,* 0. savignyi).* 



mou- 



„ gallinarum . . 



Fowls 



Spirochaetosis 



A rgas persicus. * 





,, novyi 



Man 



American relapsing 

 f ev er. 



Lice. * 





„ pertenais 



Man 



Yaws (Framboesia) 



Flies (?). 





„ recurrent is . . 



Man 



European relapsing 

 fever. 



Lice,* bed-bugs (?). 





Notes to Table IV. — Diseases of Protozoal Origin. 



Both direct and indirect methods of transmission by insects occur with diseases of 

 this class. With the intestinal parasites indirect transmission takes place by the 

 flies feeding on faeces containing the resistant stages (cysts), and later depositing them 

 on human food and drinking water either by regurgitation of the stomach contents 

 or per anum. Needless to say, infection also occurs — and perhaps principally- by 

 mechanical and aerial transmission of the cysts to food and w r ater. 



The majority of the protozoal blood- parasites have insect vectors, on which they 

 depend solely for transmission, and in certain cases these vectors are specific : 

 Malaria — Anopheles ; sleeping sickness — Glossina ; European relapsing fever 

 Pediculus. Other insect-borne blood protozoa are apparently able to be transmitted 

 by more than one vector; e.g., kala-azar may be carried by bed-bugs (Patton), 

 or by Triatoma rubrofasciata (Donovan) ; and souma (trypanosomiasis) may be 

 carried by Glossina, or by Stomoxys caMtrans. . 



