FILARIA PERSTANS 293 



from the West Coast of Africa (Congo). The author seeks to connect these 

 filariae with Filaria loa (c.f. below), but the proofs thereof are still lacking. 



LITERATURE. 



MANSON, P. The Filaria Sang. Horn., Major and Minor, two New Species of 



Haematozoa. (The Lancet, 1891, i., p. 4. Ref. im. Centralbl. f. Allg. 



Path., ii., p. 298.) 

 MANSON, P. Geograph. Distribution. ... of Fil. Sang. Horn. Diurna and of 



Fil. Sang. Horn. Persians. (Transact. Seventh Intern. Congr. of Hygiene 



and Demogr., London, 1891, i., p. 79, 1893.) 

 MANSON, P. Trop. Diseases. Lond., 1898. 



5. Filaria perstans, P. Hanson, 1891. 

 Syn. : Filaria sanguinis hominis, var. minor, Manson, 1891. 



This parasite is likewise only known in its larval stage from 

 the blood of negroes of West Africa. It is distinguished from 

 other blood filariae of man by its small size (0*2 mm. in length), 

 great motility and contractility, absence of sheath, as well as by 

 the fact that it may be observed in the blood of patients at all 

 times of the night and day. A few patients suffered from "negro 

 lethargy." The author is of opinion that these Nematodes cause 

 also the skin disease known by the negroes as craw-craw, the 

 larvae of the Nematodes appearing in the papules. According to 

 Firket, blood filariae are very frequent (55 per cent.) in the 

 negroes of various districts of the Congo region, even in children ; 

 the persons affected had no skin eruption, and were for the most 

 part in good health. One of the persons had already been in 

 Europe six years and another eighteen months. 



[Filaria perstans, in its larval form, was discovered by Sir 

 Patrick Manson in 1891 in the blood of a West African negro 

 suffering from sleeping sickness, who was under the care of Sir 

 Stephen Mackenzie in the London Hospital, Later, Manson found 

 it in blood films from natives of the Congo and Old Calabar. In 

 1897, he examined the blood of Carib Indians sent by Dr. Ozzard 

 from British Guiana, and found larval filariae closely resembling 

 those of F. perstans, together with other sharp-tailed larvae slightly 

 larger in size but equally deprived of sheath. The co-existence of 

 blunt and sharp-tailed filarial larvae in the same host was some- 

 what puzzling, and Manson provisionally gave to these filariae the 

 name of Filarice ozzardi. 



In 1898, at the post-mortem examination of two Demerara 

 Indians, Dr. Daniels found the adult form, both male and female, 

 of the blunt-tailed larvae, and soon after the adult forms of the 

 sharp-tailed larvae. This showed that the differently shaped larvae 

 belonged to two different species, one of which was undoubtedly 



