122 SANITARY ENTOMOLOGY 



Nemathelminthes : Nematoda: Ancylostomidae 



Ancylostoma duodenale Dubini, cause of HOOK WORM disease of 

 man, has been found in the egg stage in house flies, Musca domestica, by 

 Shireore (1916) in British East Africa, and it is therefore possible that 

 the eggs may be placed on food, in which the hook worm larva could 

 hatch and be directly conveyed into the body with the food. No develop- 

 ment takes place in the flies. 



Necator americanu^ Stiles, the American HOOK WORM, was collected 

 in the egg stage in the intestines of Limosina punctipennis in St. Lucia 

 by Nicholls (1912). Galli-Valerio (1905) found that flies could carry 

 on the surface of their bodies not only the eggs but also the larvae 

 of this worm. 



Nemathelminthes: Nematoda: Trichosomidae 



Trichiuris trichiura (Linnaeus), the WHIP WORM of man, was col- 

 lected in the egg stage by Shireore (1916) in British East Africa in the 

 abdomen of Musca domestica and by Nicholls (1912) in St. Lucia in the 

 abdomen of Borhorus punctipennis {Limosina) , and the latter succeeded 

 in feeding Musca domestica on the eggs. It probably does not require 

 the flies as immediate hosts, but is undoubtedly distributed in this manner. 



Thus to the already long list of serious diseases in whose spread the 

 non-blood-sucking flies may play some part we may now add hog cholera, 

 poliomyelitis, amoebic dysentery, Lamblian dysentery, Oriental sore, 

 surra, murrina, yaws, purulent ophthalmia, trachoma, the fat-tapeworm 

 of cattle, the fowl tapeworm, bilharziosis of man, the stomach worm 

 of horses, equine granular dermatitis, human ascariasis (not normal 

 method), equine pinworm, pin itch, two hook worms, and the whip worm, 

 and possibly also smallpox, measles and scarlet fever. 



We found that the bacteria were only mechanically carried by the 

 flies, except in the case of Bacillus anthracis. Among the protozoa also 

 those organisms parasitic in vertebrates all seem to be mechanically 

 transmitted. The various parasites mentioned, however, pass complete 

 life cycles in the body of the fly. Among the worms, however, there are 

 cases of external mechanical carriage, transmission of eggs through 

 the intestinal canal, retention of the egg from larva to adult fly {Ascaris 

 lumbricoides), and also cases of the fly serving as an intermediate host 

 {Choanotaenia infundihulum, and Hahronema spp.). The last named 

 worms are the only organisms known to be transmitted by the fly which 

 work forward into the proboscis for transmission at time of feeding. 

 , A bibliography of the works cited in the lecture follows : 



