FILARIA PERSTANS 295 



Professor Firket has shown that in certain districts on the Congo 

 it occurs in half the population. Moffat, Cook, Hodges and Low 

 have found the parasite to be extremely common in many areas 

 in Uganda. Low found it in 86 per cent, of the population in 

 the Sese Islands to the south of Entebbe. Moffat and Low found 

 it in 76 per cent, of the people of Unyoro ; Daniels found one 

 case in a native of British Central Africa on Lake Nyassa. On 

 the east coast of Africa it is not found in the towns of Zanzibar 

 and Mombasa, neither is it found in the country of the Masai ; 

 nor amongst the Kavirondo, who dwell along the north-east shores 

 of Lake Victoria. 



In South America, Filaria perstans is very common amongst 

 the aboriginal Indians in the interior of British Guiana, How- 

 ever, it is not found in Georgetown and in New Amsterdam, 

 neither is it found in the cultivated strip of coast lying between 

 these two towns, but it is common on the coast further north 

 near the Venezuelan boundary, where the forests stretch to the 

 sea. The Waran Indians, who live at the mo,uth of the Waini 

 river, harbour this parasite. Dr. Low, while studying filarial 

 diseases in the West Indies in 1901, never met with Filaria 

 perstans in these islands, although he examined the blood of 

 large numbers of individuals in St. Kitts, Dominica, St. Lucia, 

 Barbadoes, St. Vincent, Grenada, and Trinidad. 



Topographically, Filaria perstans is found only in areas covered 

 by dense forest growth and abounding in swamps. In Kavirondo, 

 where the forest disappears and the land is covered with scrub 

 and short grass, it is not found : likewise it is not found on the 

 grassy plains of the highlands of British East Africa. Towns and 

 cultivated areas are free from it. 



In order to find the intermediary host of Filaria perstans, Dr. 

 Low made numerous and careful experiments with many different 

 species of mosquitoes (Culex fatigans, M. atratus, C. viridus, C. 

 luteolateralis, C. quasigelidus ; Anopheles argyrotarsis, A. costalis, 

 A. funestus ; Stethomyia nimbus ; J anthinosoma musica ; Mansonia 

 africanus ; Uranotcenia cceruleocephala ; Tceniorhynchus fuscopen- 

 natus) and other blood-sucking insects (Pulex irritans, P. pene- 

 trans, Pediculus capitis and P. vestimentonim). These insects were 

 either caught in the huts of infected persons, or they were reared 

 from the larva and then fed on infected persons. After a certain 

 time they were dissected, but, with one exception, the results 

 were negative. In one isolated instance two developmental forms 

 were seen between the thoracic muscles of a Tceniorhynchus fusco- 



