IV. HUMAN FILARIASIS 
The species of the genus Filaria which are supposed to give rise to 
haematozoal embryos found in human blood are : — 
1. Filaria bancrofti, Cobbold ; syn. F. sanguinis bominis, Lewis; F. 
nocturna, Manson. 
2. Filaria diurna, Manson. 
3. Filaria perstans, Manson. 
4. Filaria demarquaii, Manson. 
5. Filaria ozzardi, Manson. 
6. Filaria magalbdesi, Manson. 
7. Filaria loa, Guvot. 
Filaria bancrofti 
Historical. The embryo of this parasite was discovered by Demarouay in 
1863 in the chylous fluid from a case of dropsy of the tunica vaginalis, who came 
originally from Havana. Wucherer, in 1866, found the embryos in the urine of 
several cases of tropical chyluria. In 1868 and following years, Lewis, Salisbury, 
Crevaux, and Cobbold observed the parasite in similar cases in or from Calcutta, 
the United States, Gaudaloupe, and Port Natal. In 1872 the history of the discovery 
of the life of this parasite entered a new phase, when Lewis found that the embryos 
had their normal habitat in the blood of man. Da Silva Lima, Crevaux, and 
Manson established the identity of these blood filariae with those occurring in 
cases of chyluria and lymph scrotum in Brazil, the Antilles, and in China. In 1876 
Bancroft found an adult worm in an abscess in a lymphatic gland in the arm, and 
later four others in a hydrocele of the spermatic cord. Since then Da Silva 
Aranjo, Lewis, Manson, and others have found adult worms in different sites. 
Manson, studying the disease in China, observed a periodicity in the occurrence 
of the embryos of the parasite in the peripheral blood, and deduced therefrom 
the function of some blood sucking insect to play the part of intermediary host. In 
1879 he demonstrated the life history of the parasite in the body of the mosquito, 
Culex ciliaris. As to how the parasite reached man again from the body of the mosquito 
several theories were advanced, until Low, in 1900, in sectioning some of Manson's 
specimens of infected mosquitoes, observed the filariae in the proboscis : which 
discovery naturally leads to the inference that they are introduced at the time of 
puncture of the skin by the mosquito. 
Description. The adult Filaria bancrofti is a long, hair-like, transparent 
nematode, three or four inches in length. Males and females often are found 
