RELATION OF INSECTS TO THE PARASITIC WORMS 71 



Besides those named about a dozen other species of mosquitoes have 

 been tested as hosts of Filaria bancrofti with negative results, or with 

 results showing that the parasites would only develop imperfectly. Fleas, 

 lice, and Stomoxys have been tested with negative results. 



Prophylaxis against Filaria bancrofti evidently consists in measures 

 similar to those employed in malaria eradication with reference to mos- 

 quito control. 



Filaria (Loa) loa (Cobbold, 1864) 



This parasite of man is a West African species. It has been brought 

 to America in the slave trade but never established in the New World. 

 The adults live usually in the subcutaneous connective tissue but have 

 been found elsewhere in relation with the serous membranes of the ab- 

 dominal and thoracic viscera. They move about from place to place 

 and can change their location rather rapidly ; for example, one of these 

 worms has been seen to cross the bridge of the nose beneath the skin 

 within a period of an hour or two. In their progress beneath the skin 

 in various parts of the body they give rise to transient edematous areas 

 known as Calabar swellings. The larvae produced by the females enter 

 the blood stream where they are found in the peripheral vessels during 

 the day time, contrary to the habits of the larvae of Filaria bancrofti. 

 Because of this characteristic periodicity of the larvae, Filaria loa has 

 been also named F. dkirna. The larvae of F. loa are provided with a 

 sheath relatively much longer than that of the larvae of F. bancrofti. 



Experiments with various anopheline and culicine mosquitoes, and 

 Glossina palpalis have given negative results as to the possibility of these 

 insects acting as intermediate hosts. From Leiper's (1913) researches, 

 it would appear that a species of Chrysops (probably C. dimidiata or 

 C. loTigicornis) acts as the intermediate host of Filaria loa, the larvae 

 undergoing their development in the salivary glands of the insect. Ac- 

 cording to Ringenbach and Guyomarc'h (1914), the intermediate host in 

 the Congo is Chrysops centuHonis. Kleine (1915) in West Africa found 

 32 out of 600 Chrysops examined, to be infested with larval nematodes 

 which he took to be the larvae of F. loa though he does not give sufficient 

 evidence to support his claims. 



Filaria demarquayi Manson, 1895 



This parasite, generally considered identical with Filaria juncea and 

 F. ozzardi, occurs in man in the West Indies and in British Guiana. The 

 adult has been found in the mesentery and under the peritoneum of the 

 abdominal wall. The first-stage larvae occur in the blood stream. Their 

 appearance in the circulation is not periodic. According to Low (1902) 



